The Barnet Book of Photography: A Collection of Practical Articles
by Various · English · Gutenberg #40468 · 482,200 chars · public domain (US)
The Project Gutenberg eBook of The Barnet Book of Photography: A Collection of Practical Articles
This eBook is for the use of anyone anywhere in the United States and
most other parts of the world at no cost and with almost no restrictions
whatsoever. You may copy it, give it away or re-use it under the terms
of the Project Gutenberg License included with this eBook or online
at www.gutenberg.org. If you are not located in the United States,
you will have to check the laws of the country where you are located
before using this eBook.
Title: The Barnet Book of Photography: A Collection of Practical Articles
Author: Various
Release date: August 9, 2012 [eBook #40468]
Most recently updated: October 23, 2024
Language: English
Other information and formats: www.gutenberg.org/ebooks/40468
Credits: Produced by RSPIII and the Online Distributed Proofreading
Team at http://www.pgdp.net (This file was produced from
images generously made available by The Internet
Archive/American Libraries.)
*** START OF THE PROJECT GUTENBERG EBOOK THE BARNET BOOK OF PHOTOGRAPHY: A COLLECTION OF PRACTICAL ARTICLES ***
THE BARNET
BOOK OF
PHOTOGRAPHY.
THE BARNET
BOOK OF
PHOTOGRAPHY.
A COLLECTION OF PRACTICAL ARTICLES
BY
CAPT. W. DE W. ABNEY, C.B., F.R.S., ETC.
CHARLES H. BOTHAMLEY, F.C.S., F.I.C.
CHAPMAN JONES, F.C.S., F.I.C.
HAROLD BAKER
A. HORSLEY HINTON
JOHN H. AVERY
W. THOMAS
ANDREW PRINGLE
JOHN A. HODGES, F.R.P.S.
REV. F. C. LAMBERT, M.A.
W. ETHELBERT HENRY, C.E.
JAMES PACKHAM, F.R.P.S.
THO'S. S. SKELTON
[Illustration]
THIRD EDITION.
Published by
ELLIOTT & SON, BARNET, HERTS.
PERCY LUND, HUMPHRIES & CO., LTD.,
3, AMEN CORNER, LONDON, E.C.
1898.
[Illustration]
CONTENTS OF
THE BOOK.
PAGE.
ALPINE PHOTOGRAPHY. _W. de W. Abney, C.B., F.R.S._ 9
NEGATIVE MAKING. _C. H. Bothamley, F.C.S., F.I.C._ 23
LENSES. _Chapman Jones, F.C.S., F.I.C._ 57
PORTRAITURE. _Harold Baker_ 77
PICTORIAL PHOTOGRAPHY. _A. Horsley Hinton_ 87
ARCHITECTURAL PHOTOGRAPHY. _John H. Avery_ 117
THE HAND CAMERA AND ITS USE. _W. Thomas_ 131
LANTERN SLIDES. _Andrew Pringle_ 141
HOW TO MAKE ENLARGEMENTS. _John A. Hodges, F.R.P.S._ 155
P.O.P. _Rev. F. C. Lambert, M.A._ 177
PLATINOTYPE PRINTING. _A. Horsley Hinton_ 197
CONTACT PRINTING ON BROMIDE PAPER. _W. Ethelbert Henry, C.E._ 225
THE GUM-BICHROMATE PROCESS. _Jas. Packham, F.R.P.S._ 241
AN INTRODUCTION TO CARBON PRINTING FOR BEGINNERS 253
THE CARBON PROCESS. _Thomas S. Skelton_ 261
ILLUSTRATIONS.
HOMEWARDS. KARL GREGER 16
AMONG THE ALPS. W. DE W. ABNEY 24
WINTER TIME ON THE ALPS. W. DE W. ABNEY 40
MELTON MEADOWS. A. HORSLEY HINTON 72
MISS LILY HANBURY--A PORTRAIT. HAROLD BAKER 88
GATHER THE ROSES WHILE YE MAY. ALEX. KEIGHLEY 120
BIRCH AND BRACKEN. W. THOMAS 136
DRIFTING STORM CLOUDS. W. THOMAS 168
STREONSALCH. W. J. WARREN 200
CUPBOARD LOVE. T. LEE SYMS 232
AT THE FOUNTAIN. J. W. WADE 264
PREFACE.
[Illustration: THE BARNET BOOK OF PHOTOGRAPHY.]
_The purpose of this book is to place in the hands of every
Photographer instructive articles on essential processes and
manipulations, by eminent writers who have given such subjects their
especial study, and who have borne in mind that whilst the
experienced Amateur and the Professional may each find much to learn
from a comparatively elementary description of methods and means, it
is the Beginner who stands in greatest need of help._
_In the mind of every photographer the name of Barnet is inseparable
from a great Photographic Industry, and now it is intended that the
name shall be associated with a good and useful book, which is
called the_ BARNET BOOK OF PHOTOGRAPHY, _and it is left to the
reader to say if the fulfilment of its purpose and the manner of its
doing are such as to justify its existence._
_To all who are interested in photography, who love it for itself
and for its productions, and who desire to improve their own
practice of its many processes and applications, this Book is
respectfully dedicated._
_Barnet, Herts._
_April, 1898._
_ELLIOTT & SON._
[Illustration: COPYRIGHT. NEGATIVE BY W. L. F. WASTELL. A FAMOUS
PIKE STREAM. Contact Print on BARNET PLATINO-MATT BROMIDE PAPER.]
_Alpine Photography._
[Illustration]
Writing in London on a day in winter with a murky sky and sloshy
streets, the title of Alpine Photography is verily refreshing. It
brings back days of sunlight and joyous experiment, and as we write
the soul stirring scenery is before us called up by photographs
taken under varying conditions of comfort and discomfort. That there
is something different in Alpine photography to photography in our
own country, we are bound to believe, since a special article is
demanded for it.
The first question invariably asked is as to the nature of the outfit
required. We should here like to divide our reply into two divisions.
The one concerning the mountaineer, and the other the ordinary
tourist. For the former we have no doubt in our minds that a hand
camera to take 1/4 plate or 5 × 4 pictures is the most convenient
form of camera to take. It is not our business to advertise any
person's wares and we shall content ourselves by saying that
personally we prefer a camera which has separate slides and does not
possess a magazine, more particularly when glass plates are to be
used, though a form of Kodak is not to be despised. But perhaps we
are prejudiced in favour of glass plates, for they are simple to
manipulate and have no cockles nor other drawbacks which the careless
photographer may have to encounter. Probably the most useful lens to
employ is a doublet of which the focal length is about a quarter more
than the width of the plate, since it includes a fair angle and the
margins of the photographs are not likely to be markedly different in
general density to the centre, as is the case when wide-angle lenses
are employed. In England a lens which will cover with a large stop,
say _f_/8, is a desideratum, but in the Alps it is very rarely that
such a large ratio of aperture to focal length is required. As a rule
for ordinary plates a lens has to be stopped down to _f_/16 to give a
negative in say 1/50th of a second. Nevertheless where orthochromatic
plates are to be employed it is very necessary to have a lens which
will cover a plate satisfactorily with _f_/8 in order to use a colour
screen for producing orthochromatic effects, since the loss of
photographic light caused by the screen can only be compensated for
by such an aperture even when the shutter is slowed down. The reader
is therefore recommended on the whole to furnish himself with one of
the modern lenses which work at _f_/8, though he must remember that
the larger the aperture employed the more the margins and centre of
the picture will suffer from unequal exposure. With some hand cameras
there is a means of attachment to a stand, but a stand on a mountain
is difficult to use and moreover has on more than one occasion been
proved dangerous to carry. The mountaineer if he desires to give a
time--and not an instantaneous--exposure on his excursion, would do
well to have a small clip ready to attach to the head of his ice axe.
The axe will form a sufficiently stable stand for the more prolonged,
but still short, exposure that he may be required to give on some
particular subjects such as a photograph at sunrise or near sunset.
Photographers in England are rarely afflicted with breathlessness
through exertion, but it is different in mountaineering. A
mountaineer may keep his wind, but it would be rare to find that his
heart was beating equably after some spurt of exertion, such as rock
climbing. It is often after some such exertion that he comes upon
some view which he may wish to record on his photographic plate. The
usual method of holding the hand camera would under such
circumstances prove a failure so far as sharpness of image is
concerned. Pressed against his "middle" or "upper" chest, the
beatings of the heart will record themselves on the photograph.
Under such circumstances resort must be had to some form of support
on which to rest his camera. After many years' experience, the
writer has come to the conclusion that there is no support superior
to the ice axe. It is not necessary to cause it to stand upright in
the ground, ice, or snow, though this should be done if possible. It
will suffice to rest the point on the rock, and place the camera on
the axe head, with the pick parallel to the body. We then have a
firm support in one direction, and the hands, which are not affected
by the automatic motion of the heart, can be trusted to keep it
steady in the other direction. Photographs taken with a good lens,
and with such a stand, will bear enlarging up to 22 inches, at
least. It is because these photographs will bear enlarging that a
small plate is recommended to the mountaineer. There is not a large
proportion of Alpine views taken on the mountain side of which one
would care to have anything but a memorandum, and it is such a size
as that recommended which gives such a memento, and which, if
desired, allows a more formidable size to be acquired at home, where
we may suppose there are all the conveniences that a photographic
laboratory affords. The writer has had experience on mountains with
cameras varying from 12 × 10 to the 1/4 plate size. When younger and
more inclined to waste a few valuable minutes of daylight in putting
up a camera stand, the 12 × 10 gave pictures which we often lamented
having taken, whilst in his more mature years, a snap-shot has never
been regretted. The cameras which require stands, require one porter
at least to carry them, for although the late Mr. Donkin carried his
own 7-1/2 × 5 camera up the highest peaks, it is few men, who, even
if they had the energy or the physique that he had, would imitate
his example. A porter means an extra expense in fees, and an extra
mouth to feed, and very likely entails slowness in a climb through
having an additional man upon the rope. A quarter plate or a 5 × 4
camera the owner, however, can himself carry; but the best form of
attaching it to his body has been a difficult task to evolve. Many
and many different attachments have been tried. One thing is quite
certain, and that is, the camera should be in a stout case, but it
cannot be carried over the shoulders by a strap as we can do in
comparatively level countries. Let anyone try to come down a rock
with the camera slung over his shoulders, and he will soon find it
dangling in front of his stomach, or swinging like a pendulum, and
threatening to displace him from what at best may be a treacherous
handhold. The method of attachment we adopt now, will be readily
seen from the diagram.
[Illustration]
The shoulder strap is utilized, but a ring is attached to the back
of the case as shown, and a strap or piece of whipcord comes over
the strap as shown. The two shoulders are in AA and the case is
carried as a knapsack. The length of the cord or strap BB is so
adjusted, as is also the length of the shoulder strap, that the
camera lies against the small of the back, and that it will not
swing away from the body. At one time the ring was placed in front
of the case, but the result was merely to cause the top of the case
to rest against the back. The plan shown above has answered under
almost every variety of circumstances, and the weight is
inconsiderable. (A friend has his camera attached to the bottom of a
small "rücksac" and this answers, but as the writer does not carry
his own provisions or change of garments he has not adopted this
plan). A long day's march may be undertaken if this contrivance be
employed, and the weight is scarcely felt.
For those who have not had extensive practice with hand cameras, a
view finder is, if not a necessity, at all events, a great help. On
the whole, perhaps the best form is that in which a miniature view
falls on a ground glass. It must be recollected, however, that each
view finder is adapted for some particular focal length of lens.
The view in the finder and on the plate should be compared, and if
the former is more extensive, the surplus ground glass should be
covered up with a black mask.
If it be determined to take a camera with its stand, very few
directions are required beyond those which apply to ordinary view
work on the plains. It may perhaps be as well to mention that a
camera stand placed on ice or snow, is not immovable until the iron
shoes of the legs attain the temperature of the surrounding snow or
ice. An exposure of a few seconds will often show an image which has
moved on the plate.
The next point that we may call attention to is the plate to be
employed. With a hand camera there is no absolute necessity to have
the most rapid plate, as far as exposure is concerned, but in
mountain work it must be recollected that there are very great
contrasts to represent on the print. "The slower the plate the
steeper the gradation" is almost axiomatic, and it must be
recollected that only a certain amount of opacity will print if the
deepest shadows only are to be kept of the greatest black obtainable
in a print. It is evident that the greater the range of light and
shade that is obtained of a printable density, the more true to
nature the picture will be. For this reason a quick plate with a
moderate gradation is to be preferred--as being most generally
useful--but it should be a plate which is absolutely free from fog,
and it should also be of as fine a grain as possible, the size of
which has something to do with development. This is still more true
when a camera stand and hand exposures are made. With a slow plate
with feebler intensities of light, which must be the case when the
lens is stopped down to admit of hand exposures, the gradation
becomes more steep than if a fairly bright light be employed. A
quick plate does not suffer in the same way, however small the stop
may be. It has already been stated that isochromatic plates may be
employed with a hand camera. For ice and snow views there is not
much to commend their employment, unless to give a deeper shade to
the sky and to the vast crevasses which so often form part of the
foreground. The darker sky allows faint clouds to be visible in a
print when they otherwise would be absent. Pictorially thus the
isochromatic plate has something to recommend it. Celluloid films
have often been substituted for plates by the writer, and excellent
photographs have been obtained on them when they were fairly rapid.
There is not much to be said in their favour as regards weight, for
in most cameras the support for them weighs nearly as much as the
glass plate. There is also a disadvantage in developing them, for
they are not so easily manipulated as a rigid body. For convenience
in travelling, however, they are to be highly commended. A gross of
cut films do not weigh so much as a dozen plates and occupy much
less space in the baggage. The question of the use of a Kodak camera
with its roller slide, has not been brought forward, not because
excellent results cannot be obtained with it, but simply because the
writer prefers to use plates and films which can be got at any time
for the purpose of development.
For travelling on the continent, and to one's mountain destination,
experience has shown that a small hamper is the safest receptacle of
all the necessary kit. A hamper which will contain two camera cases
side by side is really sufficient; but it should be a little greater
in depth. It may be thought that two cameras are to be taken, but
such is not the intention. If a zinc trough be made of the size of
one camera case it will contain all the developing apparatus
necessary, the lantern, and the plates or films, and all the few
etceteras which go to make one happy. (A screwdriver, a file, and
some extra screws, and gummed paper and white blotting paper cut to
the size of the plates should be enough for the etceteras). The
hamper may be arranged so that the camera and view finder may be
taken out without any derangement of the rest of the articles in it.
The developing bottles and cups, with the dishes, may be similarly
extracted. This prevents undue trouble in unpacking and packing. One
grand thing to remember is, pack well but not distressingly tightly,
in other words don't employ an expert packer if you wish for comfort.
Have the hamper a size too large rather than a size too small. Also
be it remembered that it is useless to stopper the bottles with all
sorts of devices at home, and have to pack in an ordinary manner when
once the contents of the hamper have been brought into use. Have your
bottles covered with an indiarubber cap which can easily be removed
and replaced; of course we are assuming that development is to take
place during one's travels, and not to be left over for home.
Personally we think that a speedy development after a view is taken
will give the best picture. It may often happen that an undeveloped
sensitive plate or film will suffer by its travels. There will or may
be scratches and what not, which would be absent if the negative is
finished at the time. The outfit for development which need only be
taken is as follows: four developing dishes, bottles or cartridges of
the dry developer, ammonia diluted to half its strength in a glass
stoppered bottle (if in a wooden case, as for medicine bottles, it
will be a further protection), a couple of tins of hyposulphite
_pounded up_ before the journey, carried in small tins (such tins as
the half-plate platinum paper comes in are very convenient), two or
three empty six ounce medicine bottles with good corks, a two or
four ounce measure, a washing rack with a trough (there is a
folding rack in the market which answers admirably; it has =v= shaped
grooves which never damage the edges of the film, and one rack will
take twenty-two glasses back to back). A zinc trough can be made to
cover the plates with water when in the rack, a lantern (by
preference a paper folding one), a dusting brush, a couple of
dusters, and blotting paper cut into squares the size of the plates,
with which to pack them--it is useful also to have spare pieces of
blotting paper to place beneath the plates when drying, also a piece
of mackintosh to place on the wash stand during developing
operations--an empty pint wine bottle will be got at any hotel and in
this the hyposulphite can be dissolved. The list looks formidable but
the whole can be readily packed in the hamper of the size given. It
will be seen that no intensifying solutions are enumerated amongst
the requisites. A negative is better strengthened in the quiet of
one's dark-room at home.
[Illustration: HOMEWARDS. KARL GREGER.]
Now we must give a hint or two as to the exposures required. We will
suppose that on the plates to be used a satisfactory negative of an
open English landscape, on a bright June day with fleecy clouds in
the sky, can be secured with an aperture of _f_/11 in 1/25th of a
second. If that be so, then on an equally fine day in July or
August, at an altitude of about 6000 feet, the same kind of view
should theoretically be secured in 1/50th second, and a stop of
_f_/16--that is, the photographic light is about four times as
strong. It must, however, be recollected that at this altitude, and
particularly near mid-day, the shadows are not illuminated to the
same degree from the sky. The darker blue sky shows that the light
which at a low altitude goes to make a pale blue sky is to be found
in the direct rays of the sun, and not scattered to give a luminous
sky. As the shadows are principally illuminated by the light from
the sky, it follows that the shadows will be darker at a high than
at a low altitude, for this reason amongst others, the exposure
should not be curtailed to the amount given above. If the aperture
be reduced to _f_/16 it is probable that the exposure of 1/25th
second will be not more than sufficient to give. For our own part we
prefer to give longer and to expose well for the deep shadows,
trusting to development to give us properly "gradated" pictures. As
the sun goes down toward the horizon, the shadows get more illumined
from local reflection, and it is scarcely necessary to alter the
exposure until considerably nearer sunset than at home, when the
exposure must be considerably prolonged. For views in which there is
little but ice and snow, the exposure should be very much curtailed.
There is so little contrast that if the exposure be at all prolonged
the picture will be inevitably flat. The shadows are illumined by an
immense quantity of light reflected from the white surface, and the
difficulty is to get sufficient contrast. The writer well remembers
one set of beautiful views, taken from the top of a mountain some
10,000 feet high, where the eye could see nothing but snow-fields
and ice and swirling masses of clouds. The day was not bright, but
to get a satisfactory picture a stop of _f_/32 was necessary with
only an exposure of 1/70th of a second. Plates given an exposure of
1/25th second with a stop _f_/16 showed little besides a plain white
mass. It would be difficult to give hints for every kind of view.
The judgment of the operator must be brought into play and no
actinometer will be of much use under the varied conditions which
are the rule, not the exception.
Now as to development. The "one-solution" given by the metol and
amidol cartridges are the most readily prepared, and in five times
out of six will scarcely be bettered, but for the sixth time may
fail, because of their "rigidity." For these exceptional negatives,
solutions of an oxidizing agent such as pyrogallol, of a restrainer
(bromide), and of an accelerator are to be recommended. For the
latter, the carbonate (not the bicarbonate) of potash is much to be
recommended, though some prefer ammonia. Two formulæ are given,
either of which will be found extremely useful. When the exposure
has been prolonged enough for details in deep shadows to be brought
out, it will generally happen that over-exposure has been given to
the high-lights, and it is to keep these in the printing state that
care is required. In the old collodion dry plate days, it was very
usual to bring out a complete phantom image of a subject before any
density was given to it. When this was properly out, the intensifier
of silver nitrate and pyrogallol was applied, and the picture
gradually brought up to printing density. It was usually full of
detail in the high-lights and shadows, all of which would be found
in the finished print. Such is the same procedure which we
recommend, strive to get out an image of feeble density but full of
detail, and then give the density.
The plate should first of all be thoroughly soaked in a solution of
the alkali which can be used, and then a few drops of the pyrogallol
solution be dropped into the developing cup with an equal number of
drops of the restrainer. The alkaline solution is then returned to
the cup and again poured into the dish and over the plate. By
degrees the required phantom image will make its appearance, and now
bromide and pyrogallol are added until it is evidently complete. The
plate is then washed in water, a final wash being given in a very
weak solution of acetic acid or citric and water. After a final
rinse with water the plate is treated with the pyrogallol solution
and restrainer in the proportion recommended for the ordinary
development of the plate, omitting the alkali. The density will
begin to appear, and when it flags, a little alkali is added (a few
drops at a time) to the solution. Keep the image fairly feeble at
above half the proper printing density, and fix. The plate should
then be kept for intensification, preferably by Mr. Chapman Jones's,
when a mercury solution is applied, and then a ferrous oxalate to
reduce the latter to the metallic state. It will be found if this
procedure is adopted, that the negative is built up with a greater
range of light gradation than by bringing it out by a one-solution
method of development. If one wishes to exercise artistic treatment,
then in the preliminary stage more importance can be given to any
desired part by applying a camel's hair brush soaked in normal
pyrogallol solution with its restrainer. The prominence thus gained
will be kept in the subsequent operations. When applying the brush
care must be taken that the image blends as it were with the rest of
the picture. No abrupt increase of density must be permitted, as if
it be, the result will be anything but satisfactory.
The following is an ammonia-pyro developer, with which the writer
usually works.
A
Ammonia 1 part.
Water 9 parts.
(Of course, should the ammonia be taken half strength allowance must
be made for the dilution.)
B
Potassium bromide 20 grains.
Water 1 ounce.
(When travelling it is very convenient to have the bromide weighed
out into 20 grain packets.)
P
Pyrogallol dry.
S
Saturated solution of sulphite of soda.
When the view has strong contrasts and the plate has been exposed
for the shadows take of A 30 minims and 2 ounces of water and soak
the plate in it as given above. Then add to the cup, of B 2 drams,
of S 1 dram, and about quarter grain of P. Pour back the solution of
ammonia from the dish, and then apply the mixture till all detail
appears, and proceed as indicated above. A saturated solution of
potassium carbonate may be substituted for the ammonia solution.
Before closing this chapter it may be of use to the reader to
tabulate the number of thicknesses of atmospheres through which
light has to travel at different altitudes of the sun at sea level.
Altitude. Atmosphere.
90° 1.000
80° 1.015
70° 1.064
60° 1.155
50° 1.305
40° 1.555
30° 1.995
20° 2.904
15° 3.809
10° 5.571
5° 10.216
4° 12.151
2° 18.882
0° 35.503
If sunlight outside the atmosphere be represented by 1 and say
1/10th be cut off by 1 atmosphere, then after transmission through 2
atmospheres only .81 will reach the spectator, and if through 3 only
.729. For any atmosphere the diminution will be 1/10th, that is, it
will be .9^_x_ where _x_ is the number of atmospheres.
If we ascend the factor varies, there are less thicknesses of
atmosphere to go through and we get the following table.
Photographically
Visual Transmission Actinic Light
Barometer (Sunlight outside Transmitted
in Inches. the Atmospheric (Sunlight outside
being 1). the Atmospheric
being 1).
30 .853 .639
29 .866 .654
28 .875 .672
27 .884 .689
26 .891 .708
25 .899 .730
24 .908 .746
23 .915 .763
22 .922 .787
21 .928 .800
20 .934 .819
19 .940 .833
This table and the preceding one will enable a calculation to be
made as to the exposure to be given. Thus at sea level with a
photographic brightness of sun of 639,000 candles when nearly
overhead, it will at 5° above the horizon only have a photographic
brightness of about 1000. At about 9000 feet high the photographic
brightness would when the sun is overhead be about 800,000 candles,
and at 5° it would have a value of 350,000, showing the greater
penetration through the thinner atmosphere.
_W. de W. Abney, C.B., F.R.S., etc., etc._
Negative Making.
DEVELOPMENT, INTENSIFICATION, REDUCING, Etc.
[Illustration]
When a sensitive plate has been properly exposed under ordinary
conditions, there is no visible change. The action of light produces
what is known as a _latent image_ or _developable image_, and in
order to convert this into a visible image with sufficient opacity
to be useful for printing purposes, it must be _developed_. In the
operation of development, the plate is treated with some solution
that will act on the exposed parts of the sensitive film and reduce
the silver salts contained therein to metallic silver, in quantity
proportional to the amount of light-action, whilst at the same time
it produces no appreciable change in those parts of the film on
which light has acted the least or not at all, and which correspond
to the darkest shadows of the object that has been photographed. The
solution used for this purpose is called the _developer_.
DEVELOPERS--GENERAL.
The substances that can be employed as photographic developers are
now somewhat numerous, but the most useful for negative making are
pyrogallic acid (also known as pyrogallol, or for brevity as pyro.),
ortol, metol, and hydroquinone (also known as quinol). Ferrous
oxalate is likewise used in special circumstances, but not for
general work. An ordinary developer as mixed for use contains:--
1.--One of the above-mentioned substances (pyrogallic acid,
ortol, metol, quinol) which is the actual developing
constituent, and is known as _the reducer_, but requires the
addition of the next constituent before it can work.
2.--An alkali, which may be sodium carbonate, potassium
carbonate, caustic soda, caustic potash, or, if pyrogallic
acid is used, ammonia. The alkali sets the reducer in action
and is called _the accelerator_.
3.--A soluble bromide, which must be potassium bromide
except when ammonia is used as the alkali, and then it may
be ammonium bromide. The chief use of the bromide is to
retard the action of the developer, and in particular to
prevent its affecting those parts of the film that have not
been acted on by light. For this reason the bromide is
called _the restrainer_ or, sometimes, _the retarder_.
4.--A sulphite, the function of which is to prevent the
solution from becoming strongly discoloured and consequently
staining the film. It also affects the colour of the reduced
silver that forms the developed image, this colour being
browner, and consequently of higher printing opacity, the
lower the proportion of sulphite present. Sodium sulphite
and potassium metabisulphite are the most commonly used.
The composition of a developer has to be so arranged that, whilst
reasonably rapid in its action, it is not so rapid as to be beyond
control, and does not produce "general fog" by acting on those parts
of the film that have not been acted on by light.
[Illustration: AMONG THE ALPS. CAPT. W. DE W. ABNEY, C.B., F.R.S.
ETC.]
DEVELOPMENT--GENERAL OPERATIONS AND PHENOMENA.
A developer is usually compounded immediately before use by mixing
two or more solutions, and in order to ensure uniform action it is
essential that the constituents should be thoroughly mixed before
the liquid is applied to the plate. If the measuring or mixing
vessel is large enough, this can be done by agitating the liquid; if
not, the liquid may be poured once or twice from one vessel to
another.
The quantity of developer necessary for a plate of a given size
depends in some degree upon the size and character of the dish that
is used, and is smallest when the bottom of the dish is quite flat
and has no ridges or grooves. It is false economy to use too small a
quantity, and it may be taken that for a quarter plate 1-1/2 oz.,
for a half plate 2-1/2 or 3 oz., and for a whole plate 4 oz. of
developer should be used.
Ebonite, xylonite, or papier maché dishes are the best for all
operations connected with negative making, since they are not so
liable as porcelain or earthenware to break a plate if it is allowed
to drop into them.
When applying the developer to the plate it is important to cover
the whole surface of the plate rapidly and in such a manner as to
avoid the formation of air bubbles, and the best way is to begin to
pour on the developer at one corner of the developing dish and
whilst pouring somewhat quickly move the vessel rapidly but steadily
along the edge of the dish to the other corner. If there should be
any froth or air bubbles on the surface of the developer, the last
portions should not be poured out of the vessel into the dish, and
then the risk of air bubbles forming on the surface of the plate
will be lessened.
Sometimes after the developer has been poured on and the plate seems
to be uniformly wetted, the liquid will recede from one corner or
one edge of the plate and the part thus left uncovered will appear
as a patch of lower opacity when the negative is finished. This
happens either because the dish is not standing level on the table
or because the bottom of the dish is not flat; sometimes it happens
because too small a quantity of developer has been used.
After the plate has been covered by the developer the dish should be
carefully rocked from time to time, and, for reasons that will be
explained presently, the time required for the first appearance of
the image and the manner in which the different parts of the image
follow one another, should be carefully observed.
If the plate has been correctly exposed, the brightest parts of the
image will appear (as black, of course,) in about a minute, more or
less, according to the temperature, composition of the developer,
and character of the plate, and the other parts will follow steadily
in the order of their brightness, after which the image as a whole
will continue to gain vigour or opacity up to a certain limit. The
essential point is that the principal details in the deepest shadows
of the subject shall appear and acquire a distinct printable
opacity, before the highest lights become so opaque that the details
in them are no longer distinguishable. Whether this condition is
realisable or not depends very largely on the exposure that the
plate has received.
If the image appears in considerably less than a minute and the
different parts follow one another very quickly, the plate has been
_over-exposed_, and the degree of over-exposure is indicated by the
rapidity with which the image appears. In this connection it ought,
however, to be stated that with metol and certain other developers,
even when the plate has been correctly exposed, the different parts
of the image appear almost simultaneously, though the first
appearance may not begin until about a minute after the developer
has been applied to the plate. It follows that with these developers
it is difficult to recognise over-exposure, but it so happens that
they are not suitable developers to use when there is any
probability that the plates have been over-exposed. On the other
hand, if the image is slow in appearing and the brightest parts of
the subject are not followed in due course by the middle tones, the
plate has been _under-exposed_, and there is considerable danger
that the high-lights may become quite opaque before any details have
appeared in the shadows, or even, in extreme cases, in the lower
middle tones, that is to say, in those parts that are next in
darkness to the shadows.
When it is desired, as it frequently is, to alter the composition of
the developer during development, the substance or substances to be
added should be put into the measuring or mixing glass, the
developer poured out of the dish into the glass, and the well-mixed
liquid poured over the plate as before. Any attempt to add
substances to the developer whilst it is in contact with the plate
will probably result in uneven action.
It should be borne in mind that temperature has an important
influence on development, the time required for the first appearance
of the image and for the completion of development being, as a rule,
less the higher the temperature. Further, if the developing
solutions are very cold, it is often almost impossible to obtain
sufficient opacity.
Perhaps the most difficult thing in connection with development is
to know when to stop the process, that is to say, when the image has
acquired sufficient opacity, or "density," as it is often called.
After all the required detail has become visible, the plate from
time to time is lifted carefully out of the developer, allowed to
drain for a moment or two, and then held between the developing lamp
and the eye; the opacity of the image, especially in the highest
lights and deepest shadows, being carefully scrutinised. The
appearance of the image as seen when looking at the back of the
plate, is also carefully observed.
For this purpose it is very much better that the light of the
developing lamp should pass through transparent glass (ruby or deep
orange) so that the flame itself is distinctly visible, instead of
through ground glass or a coloured translucent fabric. Further, the
flame of the lamp, whether gas or oil, should always be turned up to
the same height, for it is clear that if the brightness of the flame
used for making the examination is not fairly constant, all sorts of
variable results will be obtained. For this reason it is much better
to judge the opacity of negatives by artificial light than by
daylight, the intensity of the latter being so variable. A paraffin
lamp with a circular wick and a deep ruby chimney with a metal cap
at the top, answers admirably.
No general rules can be laid down; the appearance of the properly
developed image depends on the thickness of the film, the
granularity of the silver salt, the presence or absence of silver
iodide, and the composition of the emulsion used. Experience only is
of value, and the best way to secure uniformly satisfactory results,
is to keep as far as possible to one brand of plates. With some
plates, for example, very little of the image should appear at the
back of the plate, with others the greater part of the image must be
distinctly visible there.
Sometimes, especially when using small sizes of plates, it is not
easy to tell whether all the necessary detail in the shadows has
been brought out, and this is an important matter, for if the small
negatives are to be used for making enlarged negatives or prints, or
lantern slides, there should be very little clear glass indeed even
in the deepest shadows of the subject. As a rule it may be said that
when every part of the image is at least gray the maximum possible
amount of detail has been brought out. If the greyness begins to
spread to the margins of the plate where it has been protected by
the rebate of the dark slide, general fog is being produced, and, as
a rule, little will be gained, but much may be lost, by continuing
the development for any considerable time after this is observed.
When development is completed the developer is poured off, the plate
is well rinsed under the tap or in two or three changes of water,
and is then ready for fixing.
DEVELOPMENT WITH PYRO-AMMONIA.
This method of development has the advantage that the constituents
can be kept in concentrated solutions, considerable modifications in
the composition of the developer can be made very readily and the
negatives obtained are of excellent printing quality. On the other
hand it cannot be satisfactorily employed with certain brands of
rapid plates, because with them it has a tendency to produce general
fog, and with some other plates, especially when they are old, it
has a tendency to produce what is known as green fog.
Three solutions are prepared:--
REDUCER.
Pyrogallic acid 1 oz. or 10 parts
Potassium metabisulphite[1] 1 oz. or 10 parts
Water, to make up to 10 oz. or 100 parts
ACCELERATOR.
Ammonia 1 oz. or 10 parts
Water, to make up to 10 oz. or 100 parts
RESTRAINER.
Ammonium bromide 1 oz. or 10 parts
Water, to make up to 10 oz. or 100 parts
[1] The metabisulphite is dissolved in about 8 oz. (80 parts)
of water with the aid of heat, and the pyrogallic acid is
then added. When the liquid has cooled it is made up to 10
oz. (100 parts) by addition of water, the whole being well
mixed by shaking.
For each ounce of developer, take 20 minims of reducer, 20 minims of
restrainer and 40 minims of accelerator, and make up to 1 oz. with
water. With some plates 60 minims of accelerator and 30 minims of
restrainer may be used, but any greater proportion of accelerator
has considerable tendency to produce general fog. On the other hand
the proportion of restrainer can often be increased with advantage
since, unless the amount added is very large, its chief effect is to
prevent general fog; 30 minims of restrainer to 40 minims of
accelerator, or 40 minims of accelerator to 60 minims of restrainer
are proportions that can be recommended. Too low a proportion of
bromide should be carefully avoided.
It is very important to ascertain, by careful trial with each brand
of plates that is to be used, what is the maximum proportion of
ammonia that can safely be added, and what proportion of bromide to
ammonia is necessary in order to prevent general fog. As a rule, the
more rapid the plates the smaller is the quantity of ammonia that
can be used with safety.
By far the best plan is to keep development well under control by
adding only part of the accelerator at the beginning of development
and adding the rest as circumstances require.
For each ounce of developer take 20 minims of pyro solution and make
up to the required bulk with water. In another measure mix for each
ounce of developer 40 minims of bromide solution and 60 minims of
ammonia solution, and regard this as the maximum quantity that can
be added with that bulk of developer. Now to the diluted pyro
solution add about a quarter or one-third of the ammonia and bromide
solution, pour this mixture on the plate and observe what happens.
If the mode of appearance of the image indicates that the plate has
been correctly exposed, about half the remaining ammonia and bromide
mixture may be added to the developer at once, and the action
allowed to continue, with occasional rocking of the dish. If
development proceeds satisfactorily and, in particular, if the chief
details in the shadows begin to appear before the highest lights
have become too opaque, it is not necessary nor advisable to add the
last portion of the ammonia and bromide mixture, since the tendency
to general fog and green fog is reduced when the proportion of
ammonia is kept as low as possible. On the other hand, if the
development flags and the appearance of shadow detail is a little
tardy, the rest of the ammonia and bromide mixture must be added.
If the plate seems to be over-exposed, no more of the ammonia and
bromide mixture should be added for some time, until it is seen
whether the quantity already in the developer will suffice to
complete development. If it seems that the over-exposure has been
considerable, a further quantity of pyro solution (10 to 20 minims
per oz.) and also of bromide solution (10, 20, or 30 minims per oz.)
may be added with advantage. Development is then allowed to continue
and the negative is examined from time to time; if it is seen that
the opacity does not increase, or if sufficient detail in the deep
shadows does not appear, further small quantities of the ammonia and
bromide mixture may be added _cautiously_ until the required result
is obtained, waiting a little while to see the result of each small
addition before adding more.
When the plate behaves as if under-exposed, dilute the developer at
once with half the quantity or an equal quantity of water, according
to the degree of under-exposure indicated, and add the whole of the
ammonia and bromide mixture. These modifications should check the
rate at which the high-lights of the subject gain opacity, whilst
accelerating the appearance of the middle tones and shadows. Should
this effect not be produced, further quantities of ammonia and
bromide mixture may be added or, in extreme cases, ammonia alone,
and the developer may be still more diluted with water.
If any considerable parts of the image still show no detail, local
development with a brush may be tried as a last resource. A soft
camel's hair brush, preferably mounted in quill, is used. Some of
the ammonia and bromide mixture is placed in a vessel and diluted
with two or three times its volume of water. One corner or edge of
the plate is raised so that the part to be treated is lifted out of
the developer, the diluted ammonia and bromide mixture is applied
rapidly with the brush, and the plate is allowed to drop gently back
into the developer. The treatment may be repeated if necessary.
Should all these devices fail, the plate is hopelessly
under-exposed.
Sometimes, when working with a diluted developer as just described,
it happens that although all the necessary detail has been brought
out, the image gains in opacity very slowly. Provided that all the
required detail is visible, small quantities of pyro solution may be
added in order to gain opacity more quickly.
[Illustration: TEASELS By Carine Cadby.]
PYRO-SODA DEVELOPMENT.
When sodium carbonate is used as the alkali in place of ammonia the
developer acts somewhat more slowly and is less liable to produce
fog, especially with very rapid plates, and there is very little
tendency to produce green fog. On the other hand, variations are not
so easily made in the composition of the developer. Some people find
the absence of the smell of ammonia a decided advantage.
STOCK PYRO SOLUTION.
The same as for Pyro-Ammonia.
DILUTE PYRO SOLUTION.[2]
Stock pyro-solution 1 oz. or 10 parts
Water 10 oz. or 100 parts
SODA SOLUTION.
Sodium carbonate, crystallised. 1 oz. or 10 parts
Sodium Sulphite 1 oz. or 10 parts
Potassium bromide 10 grains or 0.23 part
Water to make up to[3] 10 oz. or 100 parts
[2] No more of the dilute pyro solution should be made up
than is likely to be used during the same day, but it will
keep well enough for a day or two.
[3] The sodium sulphite and carbonate are dissolved, with the
aid of heat, in about 8 oz. (80 parts) of water, the bromide
added, and the liquid when cold made up to 10 oz. by adding
water.
For use mix equal parts of dilute pyro solution and soda solution
and pour over the plate.
If the exposure has been correct the image will begin to appear in
about a minute, and development is then allowed to go on with
occasional rocking of the dish, until the negative is sufficiently
opaque.
If the plate behaves as if it were under-exposed, _at once_ dilute
the developer with an equal bulk of water and pour it back over the
plate. If the high-lights continue to increase in opacity, but the
rest of the image does not appear, add some more of the soda
solution with or without some more water. Should parts of the plate
still remain blank, apply some of the soda solution to them with the
aid of a brush as described under pyro-ammonia (page 32).
If the rapid appearance of the image indicates that the plate is
over-exposed, at once pour off the developer into a measure or
mixing glass and rinse the plate well with water. Add to the
developer a small quantity of potassium bromide solution (1 in 10 of
water) which should be kept at hand for this purpose. A small
quantity of pyro stock solution may also be added. The developer is
then poured over the plate again. When the over-exposure seems to
have been considerable, the amount of potassium bromide added may
amount to 4 grains (or 40 minims of the 1 in 10 solution) per ounce
of the developer, but this proportion should not be exceeded; even
small quantities of bromide in the pyro-soda developer have a marked
influence in retarding development.
When there is reason to suspect over-exposure, not more than half
the soda solution should be added at the beginning of development,
and the rest may be added or not, as the case may require.
DEVELOPMENT WITH ORTOL.
ORTOL SOLUTION.
Ortol 130 grains or 1.5 parts
Potassium metabisulphite[4] 65 grains or 0.75 part
Water to make up to 20 ounces or 100 parts
SODA SOLUTION.
The same as for pyro-soda.
[4] See foot-note to page 30.
Mix equal parts of ortol solution and soda solution.
This developer behaves in much the same way as pyro-soda and gives
very similar results. It has the advantage, however, that it does
not stain the fingers, and has practically no tendency to produce
either fog or stain on the plates. Moreover the same quantity of
solution can be used for several plates; when the action becomes
perceptibly slower or weaker, part of the old solution is poured
away and an equal quantity of freshly mixed ortol and soda solutions
is added.
The chief differences to be observed are (1) that the different
parts of the image follow one another more rapidly than with
pyro-soda, even though the plate may have been correctly exposed,
and (2) the colour of the reduced silver is somewhat bluer than with
pyro-soda, and therefore in order to obtain the same degree of
_printing_ opacity, as distinct from visual opacity, development
must be carried a little further.
Apart from these differences, what has been said of pyro-soda holds
good for ortol soda and need not be repeated.
DEVELOPMENT WITH HYDROQUINONE (QUINOL).
QUINOL SOLUTION.
Hydroquinone 90 grains or 2 parts
Sodium sulphite 1 oz. or 10 parts
Water to make up to 10 oz. or 100 parts
ALKALI SOLUTION.
Potassium carbonate (dry) 1 oz. or 10 parts
Potassium bromide 20 grains or 0.46 parts
Water to make up to 10 oz. or 100 parts
Mix two parts of hydroquinone solution with one part of alkali
solution and one part of water, or, if a more energetic developer is
wanted, mix equal volumes of the hydroquinone and alkali solutions.
Hydroquinone is not an advantageous developer for general purposes,
but it is useful when negatives are required showing strong contrast
between the highest lights and the deepest shadows, and especially
when it is important that there should be no deposit at all in the
deepest shadows. This is the case, for example, when copying line
engravings, pen and ink drawings and similar subjects.
DEVELOPMENT WITH FERROUS OXALATE.
This method of development also is not well adapted for general
work, but it is invaluable for certain purposes. The reduced silver
has a pure grey-black colour and there is exceedingly little
tendency to produce fog of any kind. On the other hand, the
developer admits of little modification in its composition and
therefore the exposure must be fairly correct. It is also important
to avoid contamination with even minute quantities of hypo, since
this substance very readily causes stains.
FERROUS SULPHATE SOLUTION.
Ferrous sulphate 2-1/2 oz. or 25 parts
Sulphuric acid Small quantity
Water to make up to 10 oz. or 100 parts
About three-quarters of the total quantity of water is mixed with a
small quantity (not more than 50 minims per 10 ozs., or one part per
100) of sulphuric acid, and the ferrous sulphate (proto-sulphate of
iron) which must be in clear pale green crystals without any
yellowish incrustation, is dissolved in it with the aid of a gentle
heat. After the solution has cooled, it is made up to the specified
volume with water. This solution alters when exposed to air, and
should, therefore, be kept in small (2 oz.) bottles, filled up to
the neck and tightly corked.
OXALATE SOLUTION.
Potassium oxalate 10 oz. or 25 parts
Potassium bromide 40 grains or 0.23 part
Water to make up to 40 oz. or 100 parts
For use take four parts of oxalate solution and one part of ferrous
sulphate solution, pouring the latter into the former and _not vice
versa_. In order to obtain slower action with a rather softer image
and a slightly browner deposit, the developer may be diluted with an
equal volume of water. Slower action, with slightly increased
printing contrasts, and clearer shadows, results from an increase in
the proportion of bromide.
FIXING.
After development is finished, the dark-coloured reduced silver that
forms the image remains mixed with a considerable quantity of
semi-opaque, yellowish unaltered silver bromide, which would not
only interfere with the printing, but would also gradually darken
when exposed to light. The negative must therefore be "fixed" by
dissolving out the unaltered silver bromide, and this is
accomplished by immersing the plate in a fairly strong solution of
sodium thiosulphate (formerly called sodium hyposulphite) commonly
known as "hypo." The usual strength of the fixing is as follows:
FIXING BATH.
Hypo (sodium thiosulphate) 10 oz. or 25 parts
Water to make up to 40 oz. or 100 parts
A solution of double this strength is, however, not unfrequently
used, and acts more rapidly, especially in cold weather.
The developed plate, after being well rinsed with water, is placed
in the fixing bath and allowed to remain in it with frequent rocking
until the silver bromide has all been dissolved out of the film.
This is ascertained by lifting the plate out of the dish and looking
at the back by reflected light, the plate being held in front of
something dark. It is not difficult to see whether the silver
bromide has all disappeared or not, but in order to ensure complete
fixing the plate must not be taken out of the bath as soon as this
has happened, but should be left in for a few minutes longer, the
dish being rocked so that the dissolved silver salt may diffuse out
of the film into the fixing bath.
When removed from the fixing bath the plate should be allowed to
drain into the bath for a few moments and should then be washed for
five or ten minutes in running water under the tap. It is best to
put the plate in a dish standing on the sink and have a piece of
flexible indiarubber tubing reaching from the tap to within a couple
of inches or so of the top of the dish, so that the water may not
splash too much. After washing in this way, the plate is placed in
a grooved zinc rack, which is immersed in a tank (preferably of
zinc), containing sufficient water to completely cover the plates,
and here it remains until the whole batch of plates in hand has been
developed and they can all receive their final washing together. The
plates stand upright in the rack, and the entrance and exit of the
water must be so arranged that the water enters at the bottom and
overflows at the top, or, what is perhaps better, enters at the top
and is drawn off from the bottom, the waste pipe opening at the
bottom of the tank and being bent and carried upwards until its
mouth is at the level at which the water is to stand in the tank.
When running water is not available the plates may be washed in
dishes. After being well rinsed to remove the adhering hypo
solution, the plate is covered with water (about 3-1/2 oz. for a
half plate or 5 oz. for a whole plate) and allowed to remain with
frequent rocking for five or six minutes. The water is then well
drained off, a second quantity added and allowed to remain for the
same time as before, with frequent rocking, when it is poured off in
its turn. Treatment in this way with six successive quantities of
water will remove all the hypo, provided that the film has not been
treated with alum.
Another plan, rather less troublesome, but also less expeditious, is
to place the rack containing the plates in a tank not much more than
big enough to hold it, taking care that there is not less than two
inches between the lower edges of the plates and the bottom of the
tank. After standing for some time the rack and the plates are
slowly and carefully lifted out and allowed to drain, the tank
emptied and filled with fresh water, and the rack and plates then
replaced. Eight or ten successive quantities of water applied in
this way should remove all the hypo, but if there is any doubt on
this point the plates, after they are supposed to be washed and have
been removed from the tank, should be allowed to drain into a
measuring glass or into a dish, the contents of which are afterwards
transferred to a measuring glass and mixed with a small quantity of
a solution of silver nitrate. If the plates are really completely
washed nothing will happen, or at most a white precipitate will be
produced which _will remain white_ if not exposed to daylight. If,
on the other hand, the plates still retain hypo, the silver nitrate
will produce a precipitate which will gradually become orange and
eventually dark brown. Should this happen, the washing must be
continued.
[Illustration]
DRYING.--If the negatives are allowed to dry in the rack in which
they were washed, the process is slow, and sometimes if the washing
has not been complete, the middle portions of the negatives, which
dry last, are less opaque than the rest. An excellent method of
drying negatives rapidly and in such a way that no dust can fall on
the film, is to drive nails (preferably of copper) into a wall or a
board fixed against the wall, at distances apart depending on the
size of the plates. Each plate then rests, with the film
downwards, between a pair of nails, the lower corner of the plate
resting against the wall, as shown on previous page.
[Illustration: WINTER TIME ON THE ALPS. CAPT. W. DE W. ABNEY, C.B.,
F.R.S., ETC.]
ALUM BATH.--It is frequently recommended that all plates should be
immersed in a strong solution of alum, for the purpose of preventing
"frilling" by hardening the film. Its use is, however, attended with
the great disadvantage that liquids diffuse into and out of a film
so treated with much greater difficulty than in the case of an
ordinary film, and consequently if the film is alumed between
development and fixing, the fixing is not only much slower, but the
washing after fixing requires a very much longer time. If,
therefore, the alum bath is used at all, it should not be applied
until after the film has been well washed after fixing. The
following solution may be used:--
ALUM BATH.
Alum 1 oz. or 5 parts
Water 20 oz. or 100 parts
If a strong solution of alum is applied to the plate for a long
time, the film may become so thoroughly hardened that it partially
loses its adhesiveness, and there is a possibility that it will
begin to peel from the glass after the negatives have been stored
for some time in a dry place. The solution given above is quite
strong enough and plates need not be immersed in it for more than
five minutes, after which they must, of course, be again well
washed. The hardening of the film, if not carried too far, no doubt
makes it less liable to be injured by abrasion and the like.
FRILLING.--It sometimes happens that during the various operations
of development, fixing and washing, the film begins to leave the
plate and rise in puckers along the edges. This is known as
"frilling," and in bad cases it may spread until a large part of the
film has detached itself from the glass. It is due to excessive or
irregular absorption of water by the gelatine, and at one time was
commonly met with, but it rarely occurs with the dry plates of the
present day. It is most likely to arise if there is any considerable
difference of temperature between the various liquids and the
wash-water, or during very hot weather when all the liquids are much
warmer than usual.
When frilling does occur, the plate must be treated carefully, so as
to avoid tearing the film, but unless it is very bad and shows a
tendency to spread, all the operations, including washing after
fixing, should be completed before any special measures are taken to
remedy the defect. On the other hand, if the frilling spreads
rapidly, the plate should be carefully rinsed two or three times
with water and placed for five minutes in the alum bath, with
occasional gentle rocking, after which it is again well washed to
remove the alum, and the various operations are completed. There is
one exception to the procedure just indicated; if the frilling
becomes bad while the plate is being fixed or during washing after
fixing, the alum must not be applied until the fixing and the
washing after fixing are completed. If something must be done in
these circumstances, the plate, after draining, but without any
previous washing, may be placed for about ten minutes in a saturated
solution of common salt. It can afterwards be put back into the
fixing bath, also without any intermediate washing, and the
remainder of the process carried through.
Although the methods just described will check the frilling, they
will not remove its effects. For this purpose the plate after its
final washing is allowed to drain thoroughly and is then immersed in
methylated alcohol, preferably of the old kind, though the new kind
can be made to do. The alcohol abstracts water from the film, which
consequently shrinks to its original size and can be pressed back
with the fingers into its proper position on the plate. Should the
film be opalescent it should be removed from the first quantity of
alcohol and placed in a second quantity, after which it should be
set up to dry. The plates should not remain too long in the alcohol
or the gelatine will contract too much.
DEFECTS IN NEGATIVES.
A perfect negative presupposes a perfect plate, correct exposure,
and correct development stopped at exactly the right time. It is
almost unnecessary to say that all these conditions are rarely
satisfied, and consequently most negatives fall more or less short
of perfection. The defects may be broadly grouped under two heads,
namely, those due to imperfections existing in the film before
exposure, and those due to defects or errors in the way in which the
plate has been treated. It will be more convenient to deal with the
latter, and larger, group first, but there is really no hard and
fast division between them.
THE NEGATIVE IS THIN, or in other words, whilst showing good
gradation, and sufficient relative contrast between the different
parts, is as a whole lacking in opacity or printing strength, and
gives prints that are deficient in vigour and contrasts. The plate
has been removed from the developer too soon, and the remedy is to
intensify the image (see p. 51). Sometimes the want of opacity is
due to the fact that the developer was too cold.
THE NEGATIVE IS TOO DENSE OR OPAQUE and consequently although
showing good contrasts and gradations, takes a long time to print,
especially on dull days. The developer has been too energetic, or
development has been continued too long; the remedy is to reduce the
image (see p. 50).
THE IMAGE IS "FLAT," or shows comparatively little contrast between
the highest lights and the deepest shadows. This may, of course, be
due to the absence of contrasts in the subject photographed; it is
commonly due to over-exposure; it may be caused by using a developer
containing too little reducer, or restrainer, or both, and too much
alkali; sometimes it arises from a defect in the quality of the
emulsion, or from the fact that the plate has been coated with an
abnormally thin film of emulsion.
THE IMAGE IS "HARD," or shows excessive contrasts between lights and
shadows, and is defective in the range of its half-tones. This is
probably due to under-exposure, but may have been aggravated by the
use of a developer containing too much bromide or too little alkali.
Local reduction (see p. 50) may partially remedy the defect.
FOG.--A more or less marked grey deposit of reduced silver extends
over the whole surface of the image. It may be due to over-exposure,
in which case the edges of the plate that have been protected by the
rebate of the dark slide usually remain clear. It may also be caused
by using a developer containing too much alkali, or too little
restrainer, or both, or by the plate having been exposed to actinic
light outside the camera, including the light from the dark-room
lamp if the glass or coloured fabric used as the screening material
is not efficient. In any of these cases the defect would be
observable up to the extreme edges of the film.
The character of the dark-room light should be tested by exposing
one half of a plate to it at a distance of say nine or twelve inches
for five or ten minutes, the other half of the plate being
protected by some opaque substance. The best plan is to put the
plate into a dark slide and draw out the shutter half-way. After
exposure the plate is treated with a developer in the usual manner,
and it can then be seen whether or no the light has exerted any
action on the plate.
Slight general fog may as a rule be neglected, but if the amount of
fog is at all considerable the plate should be treated with a
reducer, and afterwards the image can, if necessary, be intensified.
GREEN FOG.--The surface of the film shows a peculiar brilliant green
or yellowish-green lustrous appearance, generally in patches, when
examined by reflected light, but is more or less distinctly pink
when the plate is looked through. This effect is rarely observed
except when pyro-ammonia has been used as the developer, and it most
frequently occurs with old plates, especially if development has
been long continued or has been forced by the addition of
comparatively large quantities of ammonia.
If the green fog is only slight it does not affect the prints made
from the negative, but in bad cases the prints have a patchy
appearance and are less deeply printed at those points where the
green fog is worst. Two methods are available for the removal of
green fog.
In one of these the plate, after being fixed and washed, is placed
in a hypo solution of half the strength of the ordinary fixing bath,
and to this hypo solution is added a very small quantity of a
solution of potassium ferricyanide, and the mixture is allowed to
act on the plate for some time, the dish being rocked occasionally.
The green fog will gradually disappear and some more of the
ferricyanide may be added, if necessary, to secure this end, but it
is important to keep the proportion of ferricyanide as low as
possible, otherwise the image itself will be reduced. For this
reason, if it is seen or suspected that the green fog is likely to
be bad, development should be carried a little farther than usual in
order to allow for the slight reduction that accompanies the removal
of the green fog.
The other plan is to immerse the plate in a dilute solution of
ferric chloride (perchloride of iron) until the green fog has been
completely bleached, then wash, first in a dilute solution of oxalic
acid and afterwards in water, and finally treat with a developer,
preferably ferrous oxalate. The green fog is converted into a very
fine grey deposit which is almost invisible and has no appreciable
effect on the printing qualities of the negative.
BLACK SPOTS may be due to particles of dirt that have been allowed
to lodge on the film during one or other of the operations, or
during drying. They may also be due to particles in the emulsion,
and in the latter case are generally round and sharply defined.
BLACK MARKS of the nature of irregular streaks, looking, so to
speak, like black scratches, are generally due to mechanical
abrasion of the film. Pressure produces a developable image similar
to that produced by the action of light.
BLACK BANDS, indistinct or nebulous at the edges, are sometimes
caused during the coating of the plate with the emulsion, in which
case they, as a rule, extend all the way along or across the plate.
More commonly they are due to defects in the hinges of the dark
slides, which may produce the bands either by allowing light to pass
through, or by giving off exhalations that affect the plates if they
are allowed to remain in the dark slide for a long time. If the
bands are due to the hinges, they will, of course, correspond with
them in position, and if the hinge is double, in the distance
between them.
TRANSPARENT BANDS, or bands showing less opacity than the rest of
the image, are sometimes caused by exhalations from the material
forming the hinges of the dark slides.
TRANSPARENT SPOTS if small ("pinholes"), are generally due to the
presence of particles of dust on the surface of the plate when it
was exposed. Prevention lies, of course, in carefully dusting the
plate and the dark slide with a soft, clean, dry camel's hair brush,
before putting the former into the latter. If the spots are larger
and circular, they are due either to the formation of air bubbles on
the surface of the plate during development, or to the presence in
the film of insensitive particles.
UNEVEN OPACITY OR DENSITY, varying gradually from one end or side of
the plate to the opposite end or side, is due to uneven coating of
the plate. If there is a distinctly defined patch, less opaque than
the rest, the plate was not properly covered by the developing
solution.
STAINS.--A uniform stain, of a yellowish or brown colour, is
produced when the pyro developer contains too small a proportion of
sulphite or is allowed to act for a very long time. Such a stain is
rarely observed with the other developers mentioned above. The pyro
stain can be more or less completely removed by immersing the plate
for some time, with repeated rocking, in the alum solution given
above, 1 drachm of sulphuric acid being added to every 10 ounces.
The plate must afterwards be well washed in soft water. Similar
stains in patches may be caused by using dirty dishes or a developer
that has become turbid by being frequently used.
DEEP YELLOW-ORANGE OR BROWN STAINS, appearing gradually in patches
or all over the negative, some time after it has been fixed, and
washed, and dried, are due either to imperfect fixing or to
incomplete washing after fixing. There is no practicable remedy.
[Illustration: DOCK By Carine Cadby.]
HALATION.--When the subject photographed includes some part much
more brightly lighted than the rest, such as a window in an interior
subject, the details of the bright part are not only lost, but the
image of it seems to spread in all directions, obliterating the
details of the surrounding portions. The effect is especially
noticeable when the subject includes dark parts which necessitate a
somewhat long exposure. A window at the end of a long dimly lighted
interior, or dark trees against a bright sky are cases in point. The
effect is really due to the fact that the sensitive film is not
perfectly opaque, and some of the incident light passes through the
film and is reflected from the back surface of the glass on to the
under side of the film, producing a blurred image superposed, as it
were, on the normal image formed at the surface of the film by the
action of the direct light. The effect is known as "halation." It is
prevented by having a perfectly opaque film, which is a condition
difficult to realize in practice, and which, moreover, introduces
certain other disadvantages. It is also prevented by coating the
back of the plate with some substance that will absorb the rays that
have passed through the film, and so prevent their being reflected
back against the under side of the film. The substance used must
either be opaque or must have a deep orange, brown, or red colour,
and it must have the same refractive index as the glass, otherwise
the reflection will not be prevented. For practical convenience it
must also be easily applied and easily removed. Many substances have
been recommended but nothing is so good as caramel, prepared by the
action of heat on sugar. In order to get the mixture to dry
completely after it has been applied, a somewhat troublesome process
of purification is necessary, but caramel specially prepared for the
purpose can now be obtained from dealers in photographic materials.
The caramel (which is a solid substance) is dissolved in just enough
water to make a thick syrup, which is carefully applied to the back
of the plates in a thin layer by means of a flat brush.
If the caramel does not dry properly the solution may be thoroughly
mixed with about one quarter (or more) of its weight of very finely
powdered burnt sienna or burnt umber, "ground in water."
After being coated, the plates require some time to dry, and must,
of course, be carefully protected from light. If the dark-room is
thoroughly dark, the plates may be put up to dry in the same manner
as negatives (see page 40), but if the dark-room is not suitable,
some sort of drying box must be used.
After exposure and before development the backing is removed with a
damp sponge; if caramel only is used in a form completely soluble in
water, it need not be removed unless a developer is being used that
is to be applied to several plates in succession.
REDUCTION.
When a negative is too opaque or dense it must be reduced by
dissolving away part of the silver that forms the image. The same
process is also applied for the removal of general fog, sometimes
with a view to subsequent intensification.
The simplest solution to use for this purpose is known as the Howard
Farmer reducer and is a solution of hypo mixed with a small quantity
of potassium ferricyanide (red prussiate of potash).
FERRICYANIDE SOLUTION.
Potassium ferricyanide 1 oz. or 10 parts
Water to make up 10 oz. or 100 parts
This solution must be protected from light if it is to be kept for
any length of time.
The negative which, if it has been previously dried, must be soaked
in water for some time until it is thoroughly and uniformly wetted,
is placed in some fresh hypo solution (the ordinary fixing-bath
solution diluted with an equal volume of water) to which a small
quantity of the ferricyanide solution has been added, and the dish
is rocked repeatedly to ensure uniform action. The rapidity of the
reducing action depends on the proportion of ferricyanide solution
added, and it is very important not to add too much, otherwise the
process gets out of control and reduction goes too far. The image
should be carefully watched and the plate removed from the solution
and rapidly washed before the apparent reduction is quite as great
as it is intended to be. It is much better to stop too soon than too
late, because if it is found that a little further reduction is
necessary, the plate can be again immersed in the hypo and
ferricyanide.
The ferricyanide reducer can be applied locally for reducing
high-lights, halated windows, etc., and this is often very valuable,
especially in the case of under-exposed negatives. A small quantity
of hypo and ferricyanide solution is mixed in a measuring glass or
some other suitable vessel. The plate is immersed in plain hypo
solution in a white dish for a short time and is then raised by one
corner or one edge until the part to be reduced is above the
solution. The mixture of hypo and ferricyanide is carefully applied
with a camel's hair brush to the parts that are too opaque, and
after a few moments the plate is allowed to slip back into the hypo
solution and the dish is rocked. If the reduction is not sufficient,
the same proceeding is gone through as often as necessary. The
reducer should not be allowed to act too long before putting the
plate back into the hypo, otherwise the reduction may spread further
than is desired. Further, the reducer must not be too strong
(_i.e._, contain too much ferricyanide), otherwise it will produce
brownish stains and the action may be too energetic.
The other reducer is known as Belitzski's reducer, and is made up as
follows:--
Ferric potassium oxalate 1 oz. or 5 parts[5]
Sodium sulphite 1 oz. or 4 parts
Oxalic acid 1/4 oz. or 1 part
Hypo solution (25 in 100) 5 oz. or 25 parts
Water 20 oz. or 100 parts
[5] The formula in "parts" does not strictly correspond with
that in ounces, but the difference is immaterial.
The constituents must be dissolved in water in the order given. The
solution can be used at once and it keeps fairly well if protected
from light, in well corked bottles filled up to the neck.
INTENSIFICATION.
Intensification is a process in which the opacity of the image is
increased by adding some fresh matter, metallic or otherwise, to the
reduced silver that constitutes the developed image.
The usual plan is to bleach the image by means of a solution of
mercuric chloride (mercury perchloride or corrosive sublimate),
which converts the dark-coloured silver into a white mixture of
silver chloride and mercurous chloride, and this is subsequently
treated with some re-agent which will reconvert the image into a
dark product of greater opacity than the original.
It is absolutely essential to successful intensification that the
negative be completely fixed and completely washed after fixing, for
any trace of hypo left in the film will give rise to brown stains.
It is also important, in order to prevent stains of another sort and
to secure uniform action, that the mercuric chloride solution be
mixed with a small quantity of hydrochloric acid. Too much acid will
cause frilling. If the negative has been dried it must be immersed
in water for, as a rule, not less than half-an-hour, in order that
it may be thoroughly and uniformly wetted.
MERCURIC CHLORIDE SOLUTION.
Mercuric chloride 1 oz. or 5 parts
Hydrochloric acid 1-1/2 drachms or 1 part
Water to make up to 20 oz. or 100 parts
When uniform intensification is required the negative is allowed to
remain in this solution until it is completely bleached. If,
however, it is desired to intensify the shadows more than the
high-lights, the plate should be removed from the solution as soon
as the shadows have bleached, and should be rapidly washed in order
to stop the action on the more opaque parts of the image.
In either case the negative must be thoroughly washed after
bleaching, and the water used must be soft water. Hard water tends
to produce a precipitate of the mercury salt in the film, which may
subsequently lead to stain or fog.
Perhaps the best plan of all, when constant results are desired, is
to treat the bleached negative with the ferrous oxalate developer,
which will gradually convert the white image into a black one, after
which the plate is thoroughly washed and dried. It is recommended
that the first water used for washing should be slightly acidified
with oxalic acid.
Instead of using ferrous oxalate the bleached plate may be treated
with a weak solution of ortol or metol to which some sodium
carbonate (soda crystals) solution has been added, but _no
sulphite_. After the image has blackened completely the plate is
washed.
With any of these methods if the first intensification is not
sufficient, the plate may be again bleached with the mercury
solution and the process repeated.
An old method, frequently used, is to treat the bleached plate with
dilute ammonia, which converts the white image into a dark brown one
of very considerable printing opacity. The results are often very
good, but are somewhat uncertain, since the precise effect obtained
depends on the strength of the ammonia solution and the time during
which it is allowed to act. With somewhat strong ammonia, allowed to
act for a fairly long time, part of the intensification first
produced is removed. This affects the shadows more strongly than the
lights and the result is to increase the contrast of the negative,
which is very useful for certain purposes.
The negatives intensified with mercury solution followed by ammonia
are more liable to spontaneous change and deterioration than those
intensified with mercury solution followed by one of the developers.
The latter, in fact, if properly washed, may safely be regarded as
permanent.
URANIUM INTENSIFIER.--A very considerable degree of intensification
can be obtained by the use of the uranium intensifier, which is very
different in its mode of action, and is a little uncertain in its
results. A solution containing potassium ferricyanide and a uranium
salt, generally the nitrate, is applied to the negative, and a
deposit of a deep orange-red colour is formed upon the silver image
and very greatly increases its printing opacity. The great
difficulty is to prevent this deposit forming on the whole of the
film, and it is absolutely necessary that every trace of hypo should
be washed out of the film. The addition of acetic acid to the
solution not only promotes uniformity of action, but also helps to
keep the shadows of the image clear.
FERRICYANIDE SOLUTION.
The same as for the ferricyanide reducer.
URANIUM SOLUTION.
Uranium nitrate 1 oz. or 10 parts
Water to make up to 10 oz. or 100 parts
THE INTENSIFIER.
Uranium solution (1:10) 1 drachm or 5 parts
Ferricyanide solution (1:10) 1 drachm or 5 parts
Acetic acid (glacial) 2 drachms or 10 parts
Water to make up to 2-½ oz. or 100 parts
The negative is placed in this solution and allowed to remain with
occasional rocking until the degree of intensification is sufficient,
which can only be learnt by experience. If it is seen that the
deposit is beginning to form on the clear parts of the negative, the
plate should be at once removed. After intensification the plates are
well washed. If the water is "hard" the intensification will be
slightly reduced during washing, and this is often useful in removing
a slight stain over the whole of the plate. Treatment with water
containing a small quantity of ammonia or sodium carbonate removes
the whole of the deposit, but leaves the original image slightly
reduced and also partially altered in composition.
VARNISHING.
A negative after been thoroughly dried may be used for printing
without any further treatment, especially if only a few prints are
required and the ordinary ready sensitized papers or emulsion
papers are used. It is, however, better to protect the negative from
mechanical as well as chemical injury by means of a film of hard
varnish or collodion.
Many excellent negative varnishes can now be purchased, and the
general mode of application is the same. The negative must be
thoroughly dry, and in order to secure this and to make the varnish
flow more easily, the negative is very carefully heated in front of
a fire or over a small stove until it is just warm, but not hot. The
negative is best supported by means of a pneumatic holder held in
the left hand, and a fairly large pool of varnish (the exact amount
can only be learnt by experience) is poured on the plate somewhat
towards the right-hand top corner, and by carefully tilting the
plate it is made to run first to the nearest corner, then along the
edge to the further left-hand corner down to the nearer left-hand
corner, and back to the right-hand bottom corner, from which it is
poured into a bottle. The plate is gently rocked whilst it drains
into the bottle, and as soon as the varnish ceases to drop the plate
is again carefully warmed until the back of it is just too hot for
the back of the hand to bear, after which it is placed in a rack to
cool.
It is necessary that the varnish should be quite clear and free from
any solid particles, and if necessary it must be filtered through a
plug of cotton wool moistened with alcohol and placed in the apex of
a glass funnel which is resting in the neck of a clean and dry
bottle. Since dust may fall into the varnish whilst it is on the
negative, it is the best plan to pour the excess of varnish off the
negative into a second bottle instead of back into the first, out of
which it was poured. To put it in another way, one bottle should be
kept for the clear varnish, and a second bottle for the varnish
poured off the plate. When the second bottle is full, its contents
are filtered into the first bottle for use again.
Instead of varnish, a film of collodion, toughened by the addition
of a few drops of castor oil, and known as "leather" collodion, may
be used. The collodion is applied to the plate in the same way as
varnish except that the plate is not warmed.
_C. H. Bothamley._
[Illustration]
_Lenses._
[Illustration]
Photographs of flat objects such as leaves, lace, drawings, etc.,
can be made by simply putting the object on the sensitive surface
and exposing the arrangement to light. But this method will not
serve if the photograph is wanted of any other size than the
original, nor with solid objects of any size, except perhaps in the
production of full-size profiles of faces. It is therefore quite the
exception in photography to "print" directly from the object itself,
and the only alternative is to produce an image on the sensitive
surface.
All illuminated objects reflect light and so become for practical
purposes sources of light, just as the moon shines, as we say,
although it only shines because it is shone upon by the sun. The
simplest source of light to consider is a point of light, and if we
can get a dot of light on a white surface from a point of light we
have at once an image of that point of light. The smaller the dot
the sharper or more perfect is the image, the larger the dot the
more diffused or fuzzy is the image. It is impossible by any known
means to get the dot so small that it is an actual point, that would
be absolute perfection, and on the other hand there is no size of
the dot at which it can be definitely said that it ceases to be an
image. Every point of an illuminated object is a point of light, and
fine definition consists in keeping these points separate in the
image. So far as the dots overlap they are confused. Confusion, or
diffusion, or fuzziness is sometimes desirable, as for example in a
portrait, which may be excellent although it is impossible to
distinguish in the picture the individual hairs on the person's
head.
[Illustration: Fig. 1.]
The simplest means for getting an image is a small hole in an opaque
screen. In fig. 1, two points of light, A and B, shine through the
hole in the screen S and produce two dots of light, _a_ and _b_, on
the surface T. The two pencils of light do not practically interfere
with each other although they pass through the same small hole, nor
would any greater number; so that an illuminated object, which may
be regarded as consisting of an infinite number of points of light,
would give an image on the surface T. The disadvantages of a small
hole, or "pinhole," for the production of images are (1) it must be
so small that it lets very little light through and therefore gives
a very feeble image, (2) that it can never give a sharp image. The
first disadvantage is obvious. With regard to the second, a little
consideration will show that the image of a point must be larger
than the hole itself, it is always larger though it may have a
central brighter part that is smaller. If the hole is reduced in
size beyond a certain limit, it gives an increased spreading of
light on the surface, so that a sharp image can never be produced.
[Illustration: Fig. 2.]
Now the function of a lens is to obviate these drawbacks as far as
possible; namely, to let more light through and form a brighter
image, and to give sharper definition. In figure 2, the lens L
collects all the light that falls upon it from the point B, and
condenses it to the point _b_ on the surface T. The light from the
point A that falls on the lens is also condensed and would be
brought to a point or "focus" at _a_ beyond the surface T, but on
the surface the light forms a patch of considerable size. Suppose
that the lens is thirty times the diameter of the pinhole its area
is 900 times as large, and the light that falls upon it is 900 times
as much as the light that passes through the hole. Such an enormous
gain of light is worth so much that photographers willingly put up
with the very many imperfections of lenses for the sake of it, and
if to this gain there is added the superior definition that is
possible, it will be seen that lenses are indispensable to the
photographer. To take a Daguerreotype portrait with a pinhole might
have required several days if not weeks exposure of the plate and
therefore would have been impossible, so that the gain in brightness
of image is a great deal more than a mere convenience.
It will be observed in figure 1 that both points of light, A and B
produce images on the surface T, although they are at different
distances from it, but in fig. 2, although the effect of the lens is
to concentrate the light from both points to two other points, one
of these is beyond the surface T. This is a disadvantage inherent in
lenses. They have so many other imperfections or "aberrations" that
it is desirable to consider these separately. The reader should bear
in mind that the one aim of opticians in perfecting lenses is to
concentrate as much light as possible from each point in the object
to a corresponding point, or as small as possible a dot, in the
image, and the image should be flat because the plates used in
photography are flat.
[Illustration: Fig. 3.]
_Spherical Aberration._--The surfaces of lenses are always ground to
spherical curves, and this fact makes it impossible for a single
lens, such as that shown in figure 2, to bring to a point all the
light that falls upon it from a point. If a pencil of light passes
through a piece of glass with sloping sides it is bent or
"refracted" towards the thicker part of the glass, and the greater
the angle of inclination of the two sides the more is it refracted
from its original path. In figure 3 it is clear that the two sides
of the lens shown in section are inclined to each other at a
continually increasing angle as they approach each other at the
edges of the lens. The refracting effect of the lens increases from
the centre outwards, and it increases to a greater extent than is
necessary to bring the incident light to a point. The focus of the
pencils of light that pass through the edges of the lens is nearer
to the lens than the focus of the pencils that pass through its
central part. In the figure two foci are shown, _a_ and _b_, but of
course, in fact, intermediate parts of the lens produce intermediate
foci, and what should be a point in the image, is spread out into a
line on the axis of the lens, and all along this line is surrounded
with the light that either is coming to a focus or that has come to
a focus and has spread out again. On a screen placed at _b_ there
would be a point of light surrounded by a halo, while at _a_, nearer
the lens, the central focus or point is surrounded by a brighter or
more condensed light, and the appearance is of a circular patch of
light with a brighter boundary. This is positive spherical
aberration. Negative spherical aberration is due to over correction,
the focus of the light passing through the margins being furthest
from the lens, and the appearances on a screen are of course
reversed.
_Chromatic Aberration._--When light is refracted, that is bent out
of its original path by a single piece of glass, it is not refracted
as a whole, but each constituent behaves as if none other were
present. Ordinary white light or daylight is a mixture of many
coloured lights as seen in the rainbow, and when refracted, the blue
is bent more than the green, the green more than the yellow, and the
yellow more than the red. So that using a single lens the focus of
the blue light is nearer the lens than the focus of the red light
and the others come in between. In figure 4 this is represented in
an exaggerated degree to make it more distinct. It will be observed
that a screen placed at the focus of the blue light will show a
reddish margin and if removed further from the lens the margin or
halo will be bluish.
[Illustration: Fig. 4.]
These two aberrations, spherical and chromatic _were_ the principal
faults that opticians had to deal with, because they affect the
whole of the image, even the very central parts. But in photography
it is necessary to get an image of a very large size as compared
with the focal length of the lens, and there are some faults that
only begin to show themselves at a little distance from the centre
of the image and increase as the distance from the centre is
greater. These aberrations were, practically speaking, incurable
until a few years ago, but as recent optical advances have provided
kinds of glass by the use of which they may be eliminated, or nearly
so, they have become of practical importance. They are astigmatism
and curvature of field.
_Astigmatism and Curvature of Field._--If a diagram of suitable size
is made with a series of concentric circles and radial lines upon
it, and the centre of it is arranged exactly opposite the centre of
the lens, and in a line with the centre of the focussing screen, the
screen and diagram being parallel, then if the lens suffers from
astigmatism it will be found impossible to get the outer circles and
the radial lines where they cross them simultaneously focussed.
Where this difficulty begins the astigmatism begins, and the greater
the difference there is between the focal planes of the radial lines
and the circles, the greater is the astigmatism. It will probably
be found with any of the older types of lenses that neither is in
focus at the same time that the centre of the diagram is, but that
the screen must be racked in; this is due to curvature of field, and
the difference between the curvature of field for the circles and
the radial lines is due to astigmatism. In the older lenses a
flatter field could only be obtained by the introduction of
astigmatism, but now by the employment of the new glasses made at
Jena, it is possible to practically eliminate astigmatism, and still
keep the field flat.
[Illustration: Fig. 5.]
_The Development of Photographic Lenses._--When photography was
first practised the best lenses available were those made for use as
telescope objectives, and they had to be used with a small diaphragm
to get good definition over a sufficient field. With the slow
processes then in vogue a more rapid lens was much desired, and
Voigtlander introduced a "portrait" lens constructed according to
the results of the calculations of Professor Petzval. This portrait
lens is still very largely used, and figure 5 will serve to show its
general character and will be a guide to the putting of one together
correctly if it has been taken to pieces for cleaning. A rapid lens
such as this could not cover a sufficiently large field for
landscape work, so that single lenses were still used for work in
which rapidity was not of very great importance. Single lenses were
improved, and other kinds of lenses were introduced from time to
time, but it was not till 1866 that the "rapid rectilinears" or
"rapid aplanats," called later "rapid symmetricals," and by
innumerable other names according to the fancies of the makers, were
introduced. Probably no lens has been made in such large numbers as
this.
At about the same time, Dallmeyer introduced his portrait lens in
which the position of the convex and concave elements of the back
combination is reversed, the concave lens being outside, and this
gives the photographer the opportunity of screwing it back a little,
and so introducing a measurable amount of spherical aberration which
has the effect of modifying the otherwise exceedingly fine
definition at the centre of the field, and giving a greater depth of
definition.
In 1881, Messrs. Abbe & Schott began a series of experiments in the
manufacture of optical glasses, and they were so successful in making
new and useful varieties, that an optical glass factory was
eventually established at Jena, by Schott & Co. By the use of these
newer glasses the limitations that had previously restricted
opticians were removed, and it became possible to correct astigmatism
and secure a flat field at the same time. Zeiss of Jena, towards the
end of 1890, introduced his first series of "anastigmats." The
"concentric" lens of Ross was introduced in 1892, a lens which
probably remains unsurpassed for flatness of field and freedom from
astigmatism; but as spherical aberration is present to a notable
degree, an aperture of about _f_/22 is the largest that gives sharp
definition. The "double anastigmat" of Goerz of Berlin was put on the
market in 1893. It is a symmetrical lens, and in this different from
the Zeiss anastigmats that preceded it. It consists of two similar
combinations, each of three lenses cemented together. The unsurpassed
qualities of this lens stimulated other opticians to seek to rival
it, and there appeared similar lenses with four and even five lenses
in each combination, besides other lenses that are more or less a
copy of the double anastigmat. One of the most notable of these is
the "satz-anastigmat" of Zeiss, each combination consisting of four
lenses cemented together and forming an excellent single lens. These
combinations are interchangeable in the same mount so that with, for
example, one mount and three lenses, six different focal lengths can
be obtained, as the lenses may be used singly or any two together as
a doublet.
The "Cooke" lens is remarkable for the simple means by which the
various corrections are made, consisting as it does of only three
single lenses separated from each other. Obviously it must be used
entire. These lenses do not cover so large a plate in proportion to
their focal lengths as most of the other anastigmats, but perform
excellently over the plates for which they are constructed.
The "stigmatic" of Dallmeyer is the latest lens of general utility.
It gives good definition to the margin of the circle of light that
it transmits, reduction of aperture being necessary, when its full
field is employed, to get equality of illumination rather than to
improve the marginal definition. Its two combinations are different,
and either may be used alone as a single lens, giving focal lengths
of approximately one-and-a-half and twice the focal length of the
whole lens.
The "planar" of Zeiss introduced just as we write, is a symmetrical
doublet characterized by a very large aperture, from _f_/3.6 to
_f_/4 up to 10 inches in focal length, and a little smaller above
that. It is therefore comparable with portrait lenses. Although it
is symmetrical, a single combination cannot with advantage be used
alone as a single lens. Telephotographic lenses are subsequently
referred to.
The one aim of opticians in improving photographic lenses has been
to get good definition all over a comparatively large flat surface
without having to use small apertures. A defining power on the axis
of the lens, that is, at the centre of the field, far exceeding what
can be taken practical advantage of in ordinary photography, has
long been possible. But until recently, the defining power always
rapidly deteriorated as the distance from the centre was increased.
But to judge of the quality of a lens, or to compare one lens with
another, there are other matters that must be understood, and these
we shall proceed to consider. Focal length, aperture and image angle
are the chief details concerning lenses, granting that the
aberrations referred to above are satisfactorily corrected.
_Focal length._--The focal length or focal distance of a thin lens
is the distance between it and the point to which it converges
parallel rays. The rays of light are parallel when they issue from
an object at an infinite distance. For ordinary practical purposes,
any object, that is not nearer than a thousand focal lengths of the
lens may be regarded as at an infinite distance, that is the image
of an object so far off, and the image of the sun or stars (which
are situated at the nearest approach to an infinitely great distance
that we know of) would if separately focussed give an inappreciably
small difference of position of the focussing screen. But no
photographic lens is very thin. The measurement from the back
surface of the lens to the screen, when focussed on a distant
object, is called the "back focus," but this is of no use whatever
except as to the determining of the camera length necessary. The
"equivalent focal length" is the focal length (or focal distance) of
a thin lens that would give the same effect, so far as focal length
is concerned, as the lens in question. When the simple expression
"focal length" is used, it always refers to the equivalent focal
length. The single word "focus" is sometimes used erroneously
instead of "focal length."
The focal length of all lenses (except to a very small extent, with
single or so-called "landscape" lenses) is proportional to the
linear dimension of the image that it gives under similar
conditions. For example, a lens of 6 inches focal length will give
just the same amount of subject on a quarter plate that a lens of 12
inches focal length will give on a whole plate, because the linear
measurement of the whole plate is exactly double that of the quarter
plate. The easiest way to compare the focal lengths of two lenses,
is to focus both on a fairly distant object or view, and to measure
in the image the distance between two fixed points in both cases.
The proportion between these measurements is the proportion between
the focal lengths of the lenses. By this method the focal length of
any lens can easily be determined if one has a lens of known focal
length.
If a lens is first focussed on a distant object, and the focussing
screen is then moved back until the image of any object is of the
same size as the object, the distance travelled by the focussing
screen is exactly the focal length of the lens. It is however
exceedingly difficult to get at the same time an image of an exactly
predetermined size, and to secure the very best definition, so that
it is more convenient to get the image as near as it happens to come
to the size of the object and then to allow for the difference, as
then nothing interferes with the operation of focussing. The best
near object to use is an accurately divided scale, and the details
wanted in addition to those mentioned above are the comparative
lengths of the image and the object. To get these, two fine marks
are made on the focussing screen, and the distance between these is
the length of the image. The scale is focussed with critical
exactness and so that it falls over these marks, then the amount of
the scale represented between the marks can be measured, and the
divisions counted for the length of the object. The distance over
which the focussing screen was moved between the two focussings is
to be multiplied by the length of the object and divided by the
length of the image, and the result is the focal length of the lens.
_Aperture._--The "aperture" of a lens is the diameter of the
cylinder of light that it can receive and transmit. If the diaphragm
is in front of the lens, the hole in the diaphragm is the aperture,
but if the diaphragm is behind a part of the lens, so that the
incident light passes through a lens first, the hole in the
diaphragm is not the "aperture," the "aperture" is larger because
the lens condenses the light before it gets to the diaphragm. The
aperture of any lens can be measured by focussing a distant object,
then replacing the focussing screen by a sheet of cardboard with a
pinhole in the middle of it. In a dark-room a light must be placed
behind the pinhole, and a bit of ground glass held in front of the
lens. A disc of light will be seen on the ground glass and the
diameter of this is the diameter of the aperture, or simply, the
"aperture," with the diaphragm employed.
_Rapidity._--The rapidity of a lens depends almost wholly on its
focal length and aperture. The thickness of the glass makes a little
difference, and at every surface in contact with air there is loss
by reflection, but these and analogous matters are of comparatively
little importance, and as they are uncertain and cannot be
determined it is customary to refer rapidity to the focal length and
aperture only. The aperture found, that is, the diameter of the
effective incident cylinder of parallel rays, should be divided into
the focal length, and the diaphragm corresponding to the aperture
should then be marked with a fractional expression indicating the
proportion of aperture to focal length. Thus if the aperture is one
eighth the focal length, it is marked _f_/8, if a sixteenth _f_/16,
and so on. All lenses with the same aperture as so marked may be
regarded as of equal rapidity whatever their focal lengths may be.
Now the more rapid a lens is the shorter the exposure that it is
necessary to give for any subject, and the exposure required is
proportional to the square of the figure in the expressions as given
above. Namely 8 and 16 squared give 64 and 256 which are as one to
four, the proportional exposures required. Or we may say that 8 to
16 are as 1 to 2 and square these and get 1 to 4 the proportional
exposures.
[Illustration: Fig. 6.]
The best way to mark stops is, for example, _f_/8 and _f_/16, as
these expressions are universally understood, but some persons think
that the relative rapidities or intensities are better, others
prefer to express the relative exposure necessary, and every system
of numbering on these plans has a unit which is merely empirical,
not one of them adopting the only true or scientific unit of _f_/1.
Zeiss has recently changed his unit from _f_/100 to _f_/50.
Dallmeyer marks some of his lenses now with the practical
expression. The following table may be of service to those who
happen to have lenses with their diaphragms marked on any of these
empirical systems.
-------------------------------------------------------------------
| Royal | | | | |
| Photographic | | Paris | Zeiss | Zeiss |
_f_/ | Society. | Dallmeyer. | Congress.| (old). | (new). |
-------------------------------------------------------------------
3.16 | | 1 | 1/10 | | |
3.2 | | | | 1024 | 256 |
4 | 1 | | | | |
5 | | 2.5 | 1/4 | | |
4.5 | | | | 512 | 128 |
5.66 | 2 | | | | |
6.3 | | 4 | 4/10 | 256 | 64 |
7.07 | | 5 | 1/2 | | |
8 | 4 | | | | |
8.66 | | 7.5 | 3/4 | | |
9 | | | | 128 | 32 |
10 | | 10 | 1 | | |
11.3 | 8 | | | | |
12.25 | | 15 | 1.5 | | |
12.5 | | | | 64 | 16 |
14.14 | | 20 | 2 | | |
15.81 | | 25 | 2.5 | | |
16 | 16 | | | | |
17.32 | | 30 | 3 | | |
18 | | | | 32 | 8 |
20 | | 40 | 4 | | |
22.36 | | 50 | 5 | | |
22.6 | 32 | | | | |
25 | | | | 16 | 4 |
27.36 | | 75 | 7.5 | | |
31.62 | | 100 | 10 | | |
32 | 64 | | | | |
36 | | | | 8 | 2 |
38.7 | | 150 | 15 | | |
44.72 | | 200 | 20 | | |
45.2 | 128 | | | | |
50 | | 250 | 25 | 4 | 1 |
54.77 | | 300 | 30 | | |
63.25 | | 400 | 40 | | |
64 | 256 | | | | |
70.71 | | 500 | 50 | | |
71 | | | | 2 | |
100 | | | | 1 | |
-------------------------------------------------------------------
_Image Angle._--The image angle represents what is called covering
power. It may be expressed in terms of the focal length, and
doubtless this is the best method, but it is not customary. It may
be expressed as an angle, the angle formed when a line is drawn from
each extremity of a line equal to the diameter of the circle
covered, and caused to meet at a point distant from the base line
equal to the focal length of the lens. The angle where the two lines
meet is the image angle. But generally the covering power is
expressed more roughly, as the ordinary size of the plate that
sufficiently good definition can be obtained on.
_Tele-Photographic Lenses._--If a negative (or dispersing or
concave) lens is introduced between the ordinary lens and the plate,
the equivalent focal length of the arrangement is greater than that
of the ordinary lens alone, but the length of camera necessary is
not proportionately great. It is possible therefore to obtain an
image of a size that would otherwise require a lens of long focal
length and a corresponding and perhaps impossible length of camera.
But this is not the only advantage, for if the ordinary lens and the
negative lens are separable to a variable extent, the amount of
magnification of the image, or increase in the equivalent focal
length of the optical system, is adjustable at will. For further
details concerning tele-photographic lenses and their use, reference
should be made to Mr. Dallmeyer's pamphlet on the subject.
There are two other subjects connected with the production of images
by photographic lenses that must be referred to, though neither of
them is of great importance if we exclude the use of hand cameras
(which are separately treated of) and bear in mind the ordinary
practice of to-day. These are depth of definition and the distortion
due to the use of single lenses.
_Depth of Definition._--It has already been shown that the action of
the lens is to bring to a point in the image all the light that
falls upon it from the corresponding point of the object. Now it is
clear from fig. 2 that, if different parts of the object are at
different distances from the lens, and this must be the case with
solid objects, these different parts cannot be in focus at the same
time. Still it is possible to get them so nearly in focus that the
result is serviceable, and the ordinary method of doing this is to
examine the image on the ground glass, and if the whole subject is
not sharp enough, to reduce the size of the aperture. Depth of
definition is increased by using a lens of shorter focal length or
by reducing the aperture. If a large aperture has to be used, the
focal length must be short if much depth of definition is wanted, or
conversely, if the focal length must be long the aperture must be
small. It follows that very rapid lenses that have a very long
focus are of no use, for in portraiture, for example, this
combination of properties would lead to the ear in the image being
fuzzy if the eye was sharp.
If a lens were perfect and had a flat field, the depth of definition
would depend only on the aperture and focal length. But if the lens
gives inferior definition towards the edges of the field, it is
quite obvious that there must be less depth of definition there, if
a minimum of defining power is accepted. The definition at its best
may be inferior to the minimum accepted and then obviously there is
no depth. Depth of definition therefore at the centre of the plate
depends entirely on the focal length and aperture, but away from the
centre it depends also on the quality of the lens, and is much
greater in a flat field anastigmat than in a lens of an older type.
But depth of definition is not a quality apart, it depends entirely
upon other factors, and it is better in examining a lens to
determine these factors separately rather than to lump them together
as depth.
_Distortion_ produced by single lenses is due to the fact that the
diaphragm is either in front of or behind them. If the diaphragm is
in front, the image is drawn towards the centre of the plate to an
extent that increases as the margin of the field is approached. A
line along one side of the plate has its ends drawn in to a greater
amount than its centre, because they are further from the middle of
the plate, and therefore it becomes curved like the side of a
barrel, and this effect is called barrel-shaped distortion. If the
diaphragm is behind the lens, the displacement is outwards, also
increasing towards the edges of the field, and a straight line at
the edge of the plate becomes curved so that it is convex towards
the centre of the plate. This is known as hour-glass distortion.
Both these effects are illustrated (and exaggerated for clearness'
sake) in fig. 6, the central square representing the true figure.
This "curvilinear distortion" is absent in all cases in the middle
of the plate and generally for a considerable area, and if single
lenses of only long focal length are used, say of a focal length
equal to at least one and a half times the length of the largest
side of the plate, it may be neglected. Wide-angle single lenses
should never be used except on a suitably small plate, so that the
above conditions hold. The nearer the diaphragm is to the lens the
less is the distortion, and some of the most modern single lenses
have the diaphragm so near that the photographer is even more safe
in the use of them.
[Illustration: MELTON MEADOWS. A. HORSLEY HINTON.]
_The Comparison and Use of Lenses._--The optician when he tests
lenses looks for each fault individually, but this the ordinary
photographer is hardly able to do, nor is it particularly desirable
for him, because if a lens is inferior it matters little to him why
it is so. On the other hand occasion may arise when he wants to
identify a fault, then the information already given will probably
be sufficient to enable him to do so, if to it is added that a small
pinhole with a flame behind it is a convenient point of light, and
that if the image of this luminous point is examined with a good
eyepiece, without the focussing screen, at various parts of the
field, the character of the defect may be discovered.
The main things that the photographer needs to look to in judging of
a lens or comparing it with another, are (1) that it works to focus,
(2) the quality of its defining power especially towards the edges
of the plate. There must also be taken into account the focal length
and aperture, and if both these are not the same in the lenses to be
compared they should be nearly the same, and the proportion that the
aperture bears to the focal length should be exactly the same. A
special diaphragm may have to be cut out of card for one of them.
The best test object that is always at hand is a newspaper pinned
flat against a flat wall. The camera must not be moved during the
work. Each lens is very carefully focussed and a negative made,
using the same aperture, time of development, and in all ways
similar treatment for both. If the focal lengths are different, the
images will be of correspondingly different sizes, and then the same
detail must be compared, not the definition at the same distance
from the centre.
All good lenses work to focus, but some of the cheaper ones do not.
To test this, any series of small objects arranged side by side, but
at distances varying by intervals of say two inches from the camera,
is photographed after carefully focussing on the middle one. If any
other than the middle one is the best defined, the lens is at fault.
But in this, as in all similar tests, it must be remembered that
ordinary dry plates are not quite flat, and the error of the plate
may make an appreciable difference.
The use of lenses comprises the whole art of working with the
camera, it is therefore not our province to say much about it. But
so far as lenses themselves are concerned it may be remarked that,
if a lens has a round field, it may be advantageous to tip up the
lens with regard to the plate when only a part of the plate is being
used, as for example sometimes in taking a landscape. But in using
the modern flat field lenses special care should be taken to keep
the lens and plate exactly true to each other, the plate exactly at
right angles to the lens axis. The image and plate must coincide or
definition will suffer. If the image is rounded and the plate flat,
then in any case the result is only a compromise, but to take full
advantage of the larger apertures when the field is flat, much more
care than has been usual must be devoted to this matter.
_Simple uncorrected lenses_ such as _spectacle lenses_ or
"_monocles_," suffer from the defects that have already been
described, and are valued on this account by some workers because
they give blurred or "soft" images. With a small enough diaphragm
they will give good definition, and generally it may be stated that
reducing the aperture lessens the effect of any fault that a lens
may possess. To get the best definition that a simple lens will
give, the plate must be brought nearer the lens after focussing by
about one-fiftieth of the focal length of the lens, so that it may
be brought from the best focus of visual light into the best focus
of the photographically active light. If the object photographed is
nearer to the lens than about one hundred times its focal length,
the amount of movement after focussing must be increased. If four
focal lengths distant, the correction is nearly one-thirtieth of the
focal length, at three focal lengths distant, nearly one-twentieth,
and at two focal lengths, about a thirteenth.
_Pinholes_ give an image that for all practical purposes may be said
to be equally blurred or "soft" over the whole plate. Much has been
written about pinholes and their use, but it is not definitely known
yet whether the exposure should be longer or shorter than the
exposure required when a lens is used, allowing, of course, for the
smallness of the aperture. The following short table and exposure
rules from the writer's "Science and Practice of Photography," will
probably prove useful:--
+----------------------------+------+------+------+------+------+
| Pinholes--diameters | 1/16 | 1/22 | 1/32 | 1/45 | 1/64 |
+----------------------------+------+------+------+------+------+
| Distance from plate for | | | | | |
| sharpest image ... | 64 | 32 | 16 | 8 | 4 |
+----------------------------+------+------+------+------+------+
All the above figures are in inches. Whatever pinhole and at
whatever distance, estimate the exposure for a lens at _f_/16,
_f_/22, _f_/32, _f_/45, or _f_/64, as the case may be, and multiply
it by the _square_ of the number of inches that the plate is distant
from the pinhole. But if the distance is as given above for any
hole, it is sufficient to expose for as many minutes as the plate is
inches distant from the hole, for a subject that would require one
second with an aperture of _f_/16.
_Chapman Jones._
_Portraiture._
[Illustration]
The photographer who may be expert at landscape or architectural
work, will find himself at a loss when he essays portraiture. For
apart from the art of managing the sitter (a most important element
in producing a successful result), he will soon find that the kind
of plate that is suitable for outdoor work does not answer well for
portraits, unless the developer is greatly modified, for quite a
different kind of negative is required. As a general rule it is
advisable to use very rapid plates for portrait work; and in this
respect, at the present day we are much better supplied than even
five or six years ago, and with an extra-rapid plate it is possible
to secure a fully exposed negative in half a second, in weather and
under lighting that was quite impossible ten years ago. The best
expression and pose are generally secured when the sitter is unaware
of the actual moment of exposure; and for this purpose a silent
shutter working inside the camera is best. The sitter should never
be _asked_ to keep still unless, in groups, and when circumstances
necessitate a long exposure; and nowadays an exposure of five or six
seconds is a long one. Every effort should be made to put the sitter
quite at ease.
A head-rest should not be used unless absolutely necessary, and few
photographers are aware how easily it can be dispensed with, and
fail to realize how strong an objection nearly every sitter has to
it. It is far better to have an occasional plate spoilt by working
without the rest than to make every sitter uncomfortable by its use.
In fact some portrait negatives are actually improved by a slight
movement. In a special kind of lighting when the face is in _shadow_
relieved against a light background, a slight movement which
produces the effect of diffusion of focus greatly improves the
result.
Great care must be exercised in choosing the background even when it
is only plain or graduated, and it is well worth exposing three or
four plates on the same sitter, in the same position and lighting,
and with the same exposure, but with different backgrounds, and then
carefully comparing the resulting prints. Even if only one
background is at hand its depth can be varied by placing it nearer
or farther from the source of light. The background must also be
selected to suit the lighting of the sitter, as a background of
medium tint suitable for what is called "ordinary lighting" would be
quite unsuitable for "Rembrandt" effects, or where strong contrasts
of light and shade are used, when part of the face is in dark
shadow. For such effects a dark background is usually best, as it
gives luminosity to the shadow side of the face. But such dark
grounds are not suitable for "ordinary lighting" where the face
should be full of delicate half-tone, all of which would be killed
by the strength of the dark background.
For the Rembrandt effects a much longer exposure is necessary as
less light is reflected from the face on to the sensitive plate;
they will often need twice or three times as much as for ordinary
portraits.
When pictorial backgrounds or accessories are used it must be
remembered that the object of the photograph is to secure a portrait
of the _sitter_, not to show what a large stock of accessories the
photographer possesses. It is best to use as few accessories as
possible; I have heard a lady complain bitterly of a well-known
photographer, who having posed her in a very difficult position,
kept her waiting for five minutes while he arranged a screen, a
palm, a footstool, a tiger-skin, etc., so that she felt positively
ill before the exposure was made. The sitter should not be kept
waiting in the pose to be photographed any longer than is absolutely
necessary. If accessories must be used they should be simple and
suitable.
When portraits have to be taken in ordinary rooms it is advisable to
get a friend or assistant to experiment upon, if possible
beforehand. Even a few minutes spent in studying the possibilities
of light and arrangement of furniture will save a great deal of
worry when making the actual exposures, and nothing upsets nervous
sitters more than having all kinds of experiments and arrangements
made with them. But it is sometimes well worth wasting a few plates
on exposures which the photographer thinks will be useless, in order
to give the sitter time to get accustomed to the room; it must not
be done in a fussy, irritating way, but rather to show that it is
not such a very dreadful operation and really "doesn't hurt." This
plan often works well with nervous children, who soon become
accustomed to the room and the photographer. There is a great deal
to be said in favour of the maxim "leave your sitters alone." The
photographer must cultivate quick observation so that he sees at
once a good pose, and secures it; and here again quick plates are
essential, as many of the most charming poses are caught
unexpectedly. It has been well said that the best poses the
photographer secures are those he _observes_, not those he
_creates_. But a spontaneous pose may not be quite perfect and a
slight alteration may be easily made without disturbing the rest of
the figure. It will generally be found that a pose that takes a
great deal of arranging is not a success.
When taking portraits in an ordinary room it is usual to place the
sitter near the window, so that one side of the face is strongly
lighted and the other in deep shadow, and then use a white reflector
to light up the shadow side. It is often better, when the window is
a large one, to place the sitter farther back in the room almost
facing the window, and put the camera near the middle of the window
looking into the room; a softer lighting will then be secured. For
outdoor portraits a shady corner is best, and if possible, one where
the side light is much subdued on one side; a light head-shade may
be used with advantage. A large grey rug out of focus makes a good
background; a blanket is too light.
A portrait lens is best for the work; but if the photographer does
not possess one, he need not despair of producing good work. A rapid
rectilinear lens used at a large aperture will answer the purpose
well; it should always be used at full aperture, partly for the sake
of quickness in exposure, and partly to prevent accessories and
parts of the dress appearing too sharp and competing in importance
with the face. Subordination of parts is one of the essentials of a
picture; and if we examine a _good_ portrait we shall find that
probably no part of the photograph is quite sharp except the eyes
and face. Otherwise the less important details are apt to obtrude
themselves on our notice. A stop will generally be necessary,
however, with a portrait lens if a full or three-quarter length is
to be taken, and it will be found that heads only (as a rule) can be
taken at full aperture. Just as good work, however, can be done with
a rapid rectilinear as with a lens specially made for portraits,
except where rapid exposures are to be made; but it is necessary to
use one of fairly long focus. A rapid rectilinear lens used for
landscape work on a half plate would be much too short in focus for
giving good portraits on the same sized plate, for in order to get
the figure large enough it is necessary to place the camera so near
the sitter as to produce distortion. For portraits on a half plate a
lens of at least nine inches focus should be used and for a whole
plate not less than sixteen or eighteen inches, and longer if
possible.
The swing back of the camera will be found useful in portrait work
for getting parts of the figures into focus that are either too far
behind or too far in front of the plane of the face. For instance, a
full-length figure leaning back in a chair will have the feet out of
focus when the face is sharp if the back of the camera is vertical,
and this applies with even greater force to groups. A side swing too
is useful, but is not absolutely necessary. Even in bust portraits
the swing back is useful in getting the shoulders in focus when
using a large aperture, for although it is well not to have the
whole of the figure in _perfect_ focus all over, it is not advisable
to have the face sharp and the rest so out of focus as to be
blurred.
The development of a portrait plate should be different from that of
a landscape, because a different kind of negative is required. A
rapid plate developed so as to give a soft delicate image is best;
and a developer containing more alkali and less density giver is
good, and it may be considerably diluted with advantage. The image
should appear within ten seconds of pouring on the developer, and
the negative will generally be developed to sufficient density in
from two to three minutes. With a good average rapid plate the image
should show fairly well on the back of the plate, but this and the
time of development will vary so much with different developers, and
with the taste of each photographer that no hard and fast rule can
be laid down.
Developers that give a brown deposit, or that stain the film will
require shorter development than those of the newer developing
agents that give a cold black colour to the negative; another fact
to be borne in mind is that the image formed by these latter appears
to lose more density in fixing than when pyrogallic acid is used.
A perfect portrait negative should have no clear glass shadows, and
no part should be so dense as to give white in the finished print,
and some negatives which give the best results may have a decided
veiled appearance in the shadows.
The temperature of the developer is another important point; in very
cold weather the developer should be kept warm, or if in
concentrated solutions may be diluted with warm water. In cases of
known under-exposure the developer may be used quite hot with
advantage. A convincing experiment can be made by cutting an exposed
plate in two and developing one half with icy cold developer and the
other half with warm. The difference is really remarkable. If the
developer has been used hot enough to make the gelatine of the plate
feel "slimy" an alum bath is necessary, unless the fixing bath
contains chrome alum.
METOL.
1.
Water 100 parts or 10 ozs.
Metol 1 part or 50 grains
Sodium sulphite 10 parts or 1 oz.
2.
Water 100 parts or 10 ozs.
Potassium carbonate 10 parts or 1 oz.
3.
Potassium bromide 1 part or 1 oz.
Water 10 parts or 10 ozs.
For normal exposures take 3 parts No. 1 and 1 part No. 2; to each
ounce of mixed developer add 40 minims of No. 3.
PYRO AND SODA.
1.
Pyro 1 oz.
Water 70 ozs.
Nitric acid 12 drops
2.
Sodium sulphite 10 ozs.
Sodium carbonate (pure) 8 ozs.
Water 70 ozs.
Equal parts of each, for soft negatives dilute with water. To
restrain for over-exposure use potassium, not ammonium bromide.
Unless an acid fixing bath is used the negatives are rather green in
colour.
RODINAL AND HYDROKINONE.
A.
Sodium sulphite 1 oz.
Water 20 ozs.
Citric acid 1 crystal
Potassium bromide 1 dram
Hydrokinone 2 drams
B.
Potassium carbonate 2 ozs.
Water 20 ozs.
Rodinal 1 fluid oz.
Use 1 part A, 1 part B, and 1 part of water.
The question of retouching is a difficult one. There is no doubt
that a certain amount of it is necessary on nearly all portrait
negatives and even on those of children. But it is equally certain
that the great majority of portrait negatives are over-retouched, so
much so that their value both as portraits and pictures is nearly
destroyed. Yet a certain amount is necessary even for pictorial
effect, and perhaps still more when the question of likeness is
considered. For as a rule the untouched negative is no more a true
likeness than the over-retouched one. The truth lies somewhere
between the two. Even if isochromatic plates are used the little
differences of colour in the face, and the incipient wrinkles are
exaggerated in an unpleasant way. Under-exposed negatives will show
these defects in a very marked manner, full exposure will greatly
reduce them. Large heavy patches of shadow may be lightened by
coating the back of the negative with matt varnish, and when it is
quite hard "hatching" upon it with a soft lead. Harsh lights may be
reduced by scraping away the matt varnish with the point of a knife.
In some cases the matt varnish may be stained with a little aurine
or uranine. Exaggerated lines and small shadows must be worked upon
from the front and a retouching desk is necessary. The film of the
negative will not take the pencil without some preparation. The best
surface is obtained by spreading a little retouching medium with the
tip of the finger on the part to be touched. A thin film of soft
resin is left upon the plate which takes pencil marks readily. A
hard lead, No. 4 Faber or Hardtmuth, should be used. The loose leads
used in what are called the "ever-pointed holders" are most
convenient. The point must be very long and fine, like a large
darning needle, and is best made by rubbing the lead on a piece of
fine glass-paper. The pencil must be held very lightly and the lines
touched away with short _light_ strokes, a heavy stroke only rubs
the medium up.
The little shadow at the end of the mouth often has to be reduced,
often at the risk of spoiling the shape of the lips, but sitters
_will_ insist upon it being done, and say "You have made my mouth
much too large." Freckled faces are perhaps the most difficult to
retouch, as it is well nigh impossible to remove the black patches
caused by the freckles without at the same time destroying the
modelling of the face. Yet it must be done, for probably the most
severe stickler for truth would not insist on the black blotches
that freckles produce in a photograph.
A great deal can be done to improve a hard negative as soon as it
leaves the fixing bath, by applying a mixture of hypo solution and a
solution of ferricyanide (not ferro) of potash with a piece of cotton
wool to the dense parts. The proportions for this reducing bath are
as follows:--To each ounce of the ordinary hyposulphite of soda
fixing bath add a few drops of a 10% solution of ferricyanide of
potassium or red prussiate of potash, making the whole about the
colour of pale brandy. By adding more of the ferricyanide solution
the reducing action is quicker, but there is a greater liability to
stain the film. The work should be done over a sink with a tap of
running water at hand. The solution should be of a deep lemon colour
(it is almost impossible to give exact quantities), and after a short
application must be washed off under the tap, and the negative may
then be examined, and the reducer applied again and again till the
desired reduction is obtained. It is advisable to make a few trials
on spoilt plates. For if any really good work is to be done there
will be plenty of rejected negatives. Probably, of all the plates
exposed on portraits by first-rate professional photographers, not
more than one-fourth ever get as far as the printing-frame.
Moral: Do not be chary of exposing plates, they are cheap enough
now. Don't feel, "Oh! this will be good enough. I won't do another."
On the other hand don't expose carelessly and recklessly and say,
"It will all come right in developing." Good work is not done that
way. Use every opportunity of seeing good work. Study the work of
great portrait painters, but don't neglect the photographers. Go to
all the exhibitions of pictures and photographs within reach.
Don't be satisfied with what you have done, but make a resolve to do
something better next time. Remember, what is worth doing at all is
worth doing well.
_Harold Baker._
[Illustration: Off Boulogne. By A. Horsley Hinton.]
_Pictorial Photography._
[Illustration]
Unlike the subjects of the other articles in this book, in pictorial
photography we are not brought to consider one of the many processes
which go to make up the photographic craft, but merely a special and
exceptional application of any and all means known to the
photographer.
The particular end to which this application is made will be
explained as far as the limits of space will permit, and some of the
methods of such application will be described. Beyond this I have no
intention of going. I do not present pictorial photography as a
branch of photography especially worthy of study--I am not concerned
in making converts. It is for the photographer who has already
formed a desire to give his attention to the pictorial side of
photography and who is seeking help, that this chapter is designed.
First let us come to a mutual understanding as to the term Pictorial
Photography. Picture-making by photography would perhaps be a
simpler phrase, but that to my mind the word "picture-making" is too
similar in idea to boot-making, lace-making, etc., all of which
imply a mechanical manufacturing, whereas a picture--a real
picture--like a musical composition, a poem or a beautiful thought,
grows or is evolved rather than made to order.
Art photography would be a better term, but that in photography the
word "art" has been so often coupled with things the very antithesis
of artistic and might hence be misleading, moreover the photographer
will show discretion rather than weakness if he be not too hasty to
claim for photography a position among the arts, and whilst its
claims to that dignity remain as yet in dispute, we may be content
with "Pictorial Photography" as a less assuming title, yet one which
will sufficiently differentiate between what we may call the
ordinary photographic production and---- Well, what?
That is the first thing I have to try and explain.
Look at the illustrations in this book on pages 72, 136, and 120,
and, making due allowance for some loss of quality due to
reproduction by a "half-tone" block, try to imagine what the
originals were like. Then say if they please you. If you say no, you
do not care for them, they do not appeal to you, you do not mind if
you never saw anything of the kind again from this day henceforth;
very well, doubtless there are other things in the world in which
you can find pleasure, but so far as my present subject is
concerned, here you and I part company. These illustrations are more
or less successful reproductions of pictorial work, and if you do
not like them, making as I have said due allowance for their being
reproduced and reduced, then it is certain you do not want to hear
anything about them, and it is not my intention to persuade you, so
please pass on and make room for those who do care for these things
and wish to learn all they can concerning them, or at most stand
aside and peradventure some stray word dropped unintentionally may
quicken your interest and discover in you a sympathy of which you
were previously unconscious.
[Illustration: MISS LILY HANBURY--A PORTRAIT. HAROLD BAKER.]
Referring now again to the illustrations which in the absence of
anything else we take as fairly typical of pictorial photographs and
assuming that one or the other, if not all, do please some of my
readers, I will ask them to endeavour to analyse their feelings when
confronting such productions.
Take now an ordinary commercial photographic view such as one may
purchase from any sea-side stationer, and compare the sensations
awakened by each. In the case of the topographical view we feel some
satisfaction at being able to recognise a familiar spot, or the view
reminds us of some other place, or it may be quaint buildings, or
rugged mountains, or miles of foliage, or what not inspire curiosity
or interest because we know the photograph to be a true record of
facts, that is to say we accept the photograph in lieu of the actual
presence of the objects represented, and experience nearly the same
feelings as we should were we to visit the spot represented. We know
that the wonderful, curious, or unusual things portrayed have an
existence, otherwise we could not have a photograph of them.
In all such cases our interest and value of the photograph would
vastly diminish, were it possible for a photograph of this kind to
be made simply by the photographer's hand and imagination without
any original at all.
You look at a photograph of this or that sea-side place and remark,
"Ah, yes, that's dear old Yarmouth, many a time, etc., etc.," or
else, "Dear me, I wonder what place that is, it's so like----" such
and such a town, or it may be you enquire "Where's that?" and you
express or think to yourself you would like to go and visit the
spot. These and kindred sensations are those kindled by the average
photograph, but there is yet another, for you may be impelled to
exclaim, "How wonderfully clear and bright that photograph is,"
"What a good photograph." In this case you are interested purely in
the execution as an example of clever manipulation and skilful
craftsmanship.
Now, compare such feelings as these with those stirred by an example
of good pictorial work. In the first place your esteem for it, if
you value it at all, is quite as great whether you know the place
where it was made or not. If it pleases you, that pleasure is not
dependent upon the fact that it does represent some place. In the
case of paintings and drawings as often as not they do not pretend
to represent any place at all, but are pure fiction, yet we do not
value them the less. To what then is the pleasure we feel when
looking at a good picture due? Is it not that a picture stirs up,
that is, _creates_ pleasant or beautiful thoughts and ideas--by
pleasant I do not mean necessarily merry or joyous ones, for some
hearts feel profounder pleasure in the grandeur of storm or the
majesty of the mountain than in the sweet wilderness of flowery
wastes, but notice that such beautiful ideas are _created_ by the
picture. You were thinking of something totally different before you
came upon the landscape picture which instantly made you feel the
glowing light, the stirring breeze, and hear the rustling corn and
noisy brook, and yet it cannot be said it is because we _recognise_
these things in the picture that we receive these impressions, at
least it is not the kind of recognition which takes place when we
see a photograph of Brighton Pier or Haddon Hall.
Notice, it is not the exact and faithful portrayal of objects that
creates the emotions instanced, for if you closely observe the
manner in which a good painting is done you will find that rude
splashes of paint, broad brush strokes, and the like stand for
foliage or water, or corn stalks as the case may be, when we know
that had the painter desired he _could_ have produced his likeness
of nature with a good deal more of the precise detail and fidelity
to outlines which photography excels in, _had he wished_. But if the
painter or other pictorial artist needs not to trouble about
accuracy to details to secure the effect aimed at he must be
faithful to general facts. There is a great difference between not
recognising things or having no particular wish to do so, and
feeling conscious that a portrayal is so utterly unlike anything in
our past experience of nature that we should not recognise the
objects even if we _were_ acquainted with them. To take an extreme
case--our enjoyment of the effect and sentiment of a beautiful
landscape picture is not enhanced by our being able to recognise
whether the trees are oaks or elms, but it would be distinctly
disturbed if the palm trees were represented as growing on the
slopes of a Welsh mountain. Innumerable examples and instances might
be given to show that the artist, whatsoever his medium, be it
colour or monochrome, may depart from truth, or may be indifferent
to precise details, _only so far as he avoids palpable untruth_.
Why is this?
When we look at a powerful and impressive picture we feel at once
the sentiment, our emotions are at once stirred, subsequently we
recognise objects and facts portrayed, but only when we begin to
look for them or think about them; but a gross exaggeration or a
very obvious error strikes us at once before we begin to receive
sentiments and ideas, and that error or exaggeration once seen is
never lost sight of, and whole enjoyment of the picture is
hopelessly marred.
Now, from the foregoing (for want of space I am aware that the
argument is incomplete, and must therefore ask the student to think
the matter out and grasp the side issues by reading between the
lines) we may formulate the broad definition that a picture does not
depend for its excellence on the faithful representation of objects,
and is not chiefly valuable on account of our immediate recognition
of things portrayed, yet on the other hand it must not let us feel
that there is obvious inaccuracy.
Here then we have two opposite positions in both of which the mere
objects employed to build up the picture are subordinated to the
effect or impression of the picture. In one case the spectator must
not be allowed to feel that the representation is _wrong_, in the
other success will not directly depend on the representation being
very _right_, neither startling rightness or truth nor the obvious
wrongness or untruth should thrust the objects composing the picture
upon the beholder's attention, he should be left free to receive the
expression or sentiment of it.
I hope the reader is following me in this line of thought closely. I
am aware that it may seem dry and uninteresting, but I see no other
way of placing the student in a proper position at the outset than
by explaining the essential elements of pictorial work, and I will
make this introductory part as brief as possible.
Reverting now to our argument, I have in other words suggested that
obvious violation of truth will prevent the sentiment or effect of
the picture from being paramount, and now I will submit that an
excess of accuracy to detail is equally detrimental to the success
of a picture as a picture.
If by now the reader is prepared to admit that the chief purpose of
a picture is the feelings, emotions, ideas which it suggests or
creates, and not the facts it portrays, he will be able to go
further and perceive that in a landscape, for instance, cottages,
trees, or what not are introduced, not for their own intrinsic
interest but as vehicles of light and shade, which go to express the
picture's sentiments.
If we stand before a good picture with closed eyes and suddenly open
them, our first impression (precluding any question of colour) is
that of masses of light and shade pleasingly and harmoniously
arranged; if we retreat to such a distance that the objects
constituting those lights and shades are unrecognisable the balance
and pleasing arrangement should still be felt, and our æsthetic
sense is satisfied, although we do not see fully of what the picture
is composed. This is the quality which is termed breadth and which
is admittedly of very great value.
If on the other hand the shadow masses are filled with innumerable
details, and are thus broken up into tiny lights and shadows they no
longer exist as broad masses of dark, but if before retreating as
proposed from the picture, the lights or shadows appear so blank as
to prompt particular investigation, and upon examination we find
detail absent which we know must have been present, then we
encounter an instance of untruth and exaggeration which is obvious
and which disturbs our appreciation of other fine qualities. Thus we
require _sufficient detail to avoid giving the idea that detail is
left out_.
The delineation of sharp outlines and redundance of detail is not
wrong in itself, but it is usually inexpedient when considered with
respect to the effect to be produced, similarly the suppression of
sharp focus both as regards outlines and details has no artistic
merit of itself except as it assists the picture to impress the
beholder first with the general effect.
The painter and photographer start from two opposite standpoints.
The painter, or draughtsman, starts with nothing but blank paper,
and having built up his picture and produced his desired effect he
elaborates no further; the photographer with his more or less
mechanically produced _facsimile_ starts from the opposite extreme
with a transcendentally elaborate image, from which he will require
to eliminate all such excess of truth as is likely to force the mere
facts of the view upon the beholder's attention.
Photography, so faultlessly complete in its delineation, gives us
_more than the pictorial worker needs for the expression of an
idea_, and this is why I would remind the student that pictorial
photography is not photography in the full sense of the word, but
the application of some of its powers, just as much as we need and
no more, to a definite end.
As just hinted the purpose of a picture is to express ideas, hence I
will fall back on a kind of definition which I have used on a
previous occasion that a picture is the portrayal of visible
concrete things for the expression of abstract ideas.
To give an example by way of exposition we may look upon a picture
and be made to feel by it the calm and luminous atmosphere of
evening; we feel at once the restfulness, and almost feel the warmth
of the humid air, giving place to the chill gathering mists of
night; but the same objects, the same tangible materials, paper,
pigment, metallic salts, etc., in another picture give us the sense
of angry turbulent storm or perhaps bright joyous sunshine
frolicking with the fresh breezes on the hill-tops. These are
abstract ideas expressed or created by the manner in which concrete
things, commonplace facts, are portrayed and rendered.
Finally, let me enunciate that a very excellent photograph may not
necessarily be a good picture, because it may contain more than is
required for the expression of its idea, and the surplus will
overwhelm it; again, a good pictorial photograph may be but a poor
photograph, because if we claim the right to apply photographic
means to pictorial ends, we may find it convenient to leave out the
very qualities which the scientific or technical expert considers
most precious.
And now I think we may proceed to more practical matters.
COMPOSITION AND SELECTION.
In all matters from which the eye expects to derive pleasure,
symmetry of design seems essential. In the formation of the letters
that we write, in personal attire, in the decoration of our homes,
in buildings, and practically in everything which is not of a purely
utilitarian character, a sense of proportion and a symmetrical
disposition of parts is observed. Hence it is no source of surprise
that in a picture which as much as anything should aim at pleasing
the eye, design, otherwise Composition, is with Expression a
co-essential.
In a purely decorative production this natural desire of design is
the only thing to be observed, but in a picture which _may_ be
decorative, but _must_ be something more, we have expression as well
to consider. If decoration alone were to be regarded, something like
fixed rules might perhaps be tyrannically laid down, but in a
picture the implicit observance of rules of composition would be
certain to make itself seen in the result, and the undue
obtrusiveness of a code of rules would be as inimical to the
supremacy of ideas and feelings, as the excessive prominence of fact
would be, which has already been described.
Hence the difficulty in prescribing any definite course for the
beginner, because whilst to most instinctive artistic temperaments a
certain knowledge of or feeling for composition is natural, so soon
as this is reduced to definite rule and given to another, the, as it
were, secondhand use, is nearly certain to betray itself by its
misapplication. I would ask therefore that any suggestions given
here on the subject of composition should be taken as one takes
lessons in the rudiments of a language, which rudiments we violate
and forget so soon as we have become proficient enough to speak it.
_Such rules in composition should be observed only so far as to
avoid the appearance of having infringed or ignored them._
The rules of composition which may be found to apply in one of the
pictorial arts must necessarily apply equally in the others, and so
therefore to pictorial photography which at least aspires to be
considered an art. If on a sheet of paper a rectangular space is
given us wherein to draw the likeness of anything, the most natural
course to pursue would be to draw that figure in the centre or
thereabouts, and if then we are asked to add the likeness of two or
three more objects we should naturally place these near the first
object. Thus should we compose a group of objects which draw the
attention to the middle of the picture or space.
Suppose we are asked to draw the picture of a church tower we should
probably comply with the request somewhat as shown in fig. 1. Next
we will suppose we are asked to add a cottage, some trees, and a
path to the church, we should, if possessed of some sense of
symmetry and order, coupled with average intelligence, make the
additions somewhat as in fig. 2. It would surely be an unusual thing
to follow instead the course suggested by figs. 3 and 4.
In figs. 1 and 2 we have instinctively placed the primary object in
or near the centre, and the others near and around it, and the
result strikes one at once as being better composed, that is, more
symmetrical, than in fig. 4, in which amongst other things one is
not sure which object to regard as the principal one, and one also
feels that but for the boundaries of the picture left and right we
might have seen a good deal more beyond, which would have added to
the interest of the picture.
[Illustration: Fig. 1.]
[Illustration: Fig. 2.]
[Illustration: Fig. 3.]
[Illustration: Fig. 4.]
In this we have one of the first rules in composition, namely, that
the principal object should be near the centre, and the next
important near to, and as it were supporting it, and no object
likely to attract the eye should be so near the edge of the picture
as to make us instantly conscious of the boundaries and wish to see
more beyond.
But now if in compliance with the supposed request we had made our
drawing as in fig. 5, might it not at once be felt by the observer
that we had put the objects in a central position _intentionally_,
which is equivalent to saying that we had allowed our endeavour to
observe the rule just laid down to betray itself. Fig. 2 is
preferable as being only just sufficiently symmetrical to avoid
being unsymmetrical, which is an example of what has already been
said about the necessity of observing rules of composition just so
far as to escape the appearance of having broken them.
[Illustration: Fig. 5.]
[Illustration: Fig. 6.]
If this rule is right as regards voluntarily drawing a picture, it
is equally so in the case of a photograph, but instead of
deliberately placing things in such and such positions, we attain
the same end by moving the camera and selecting our point of view so
that the objects come into the positions desired.
Now suppose then, we have done this, but in doing it we are quite
unable to prevent other objects coming into the field of view and
occupying undesirable places near the margins of the picture, as for
instance in fig. 6. Here we are brought to consider another rule or
principle in composition, namely, that there must be one and only
one chief object in the picture, whereas in fig. 6, apart from the
gate and tree on the one side and the windmill on the other
attracting attention to the margins of the picture, these same
objects arrest the attention quite as much as the church, and we
feel the eye wandering about from one to the other and missing the
sensation of centralization and rest which fig. 2 gives.
If we were drawing or painting we should put in what we want and
then stop, we should omit or ignore what we did not require, but in
photography our powers in this direction are limited, and hence we
must as far as possible select those views, and only accept such, as
comply with what we feel to be right.
The angle of view included by different lenses is an auxiliary not
to be neglected, for by substituting a narrower angle lens, that is,
one of longer focus, we may cut off or leave out undesirable objects
which the shorter focus lens might include. Then again, when the
print is finished we can after careful consideration cut off what
would have been better left out, for it will be better to have a
picture half the size well composed, than double the number of
inches with a distracting and unsatisfactory arrangement of objects,
hence with many most successful workers it is no uncommon thing to
take quite a small portion of a negative, and either print it as it
is or else enlarge it up to the desired size, but mere size will
reckon as nothing as compared with pleasing composition.
If it is inexpedient to let the principal object or group of objects
occupy the exact centre of the picture, measured from left to right,
it is equally so if the centre be measured from top to bottom, and
hence we may formulate the rule (to be broken perhaps later when we
are strong enough to be independent of guiding) that the horizon
should not be allowed to come midway between the top and the base of
the picture.
[Illustration: Fig. 7.]
[Illustration: Fig. 8.]
Remembering now that, as set forth in the earlier part of this
article, a picture should appeal to our feelings and stir our
emotions, it may be pointed out that in most ordinary things, and
certainly in the arts, the most powerful things are those which
possess _one_ dominant idea or feature, as in a piece of music the
refrain keeps recurring, a preacher takes a text, in a story there
is _one_ hero, and so forth, and in point of composition fig. 7 is
better than fig. 8, although the view is less comprehensive.
[Illustration: Fig. 9.]
It may not, however, always be easy for the beginner to determine
what is the chief object which should occupy the central position,
or which object or group to choose in a landscape.
[Illustration: Fig. 10.]
This brings us to speak of another important matter, and that is the
right disposition of lines which form the view or the selection of
view so that the lines formed by the component parts shall fall in a
desirable manner. The various objects in any view tend to form or
suggest lines, thus in fig. 9 the outline of the trees, the bank
along the shore, the clouds, and the boats suggest the lines shown
in the diagram, fig. 10, which lines all run the same way, but in
fig. 11 we have a similar view in which the lines suggested
counterbalance each other, and not only so, but by their convergence
they carry the eye to a spot near the centre, and so make the boat,
although not very large nor conspicuous, the one and principal
object (see diagram fig. 12).
[Illustration: Fig. 11.]
[Illustration: Fig. 12.]
For the sake of training one's perceptions look at any good
pictures, and in your mind resolve them into line diagrams and see
how these lines fall, and in considering any landscape or other
subject to be photographed make up your mind as to what lines are
suggested, and then select your point of view so that these lines
balance or are symmetrical in arrangement, and also that they
converge towards some point well within the picture, and near the
centre of it.
[Illustration: Fig. 13.]
But in fig. 13 we have a subject in part well composed, but the
composition is spoilt because of the line formed by the road and
fence, which seem to cut the picture in two, whereas could we have
chosen the same subject from a point of view giving such an
arrangement as fig. 14, a difference is at once felt and a more
pleasing effect gained.
[Illustration: Fig. 14.]
[Illustration: Fig. 15.]
[Illustration: Fig. 16.]
Lines which seem to separate us from the picture and cut off one
part from another must be carefully avoided, and an endeavour to
find something which will, as it were, lead the eye into the
picture, should be diligently sought for, and indeed a subject,
however it may interest us, must often be abandoned if it lacks
those things which go to make pleasing composition, remembering as
we should always do that in pictorial work the fact that objects are
curious, or interesting, or pretty, has nothing to do with the case,
but that they are only to be valued according as they act as media
for expressing pleasing ideas, beautiful thoughts and sentiments,
which they will not do if some part creates a feeling of unpleasing
arrangement or design. If a scene does not compose well, we should
as pictorial workers feel no desire to reproduce it. But you may say
"Cannot we often by changing our point of view get an otherwise
ill-composed subject to compose well?" Most decidedly, that is
precisely what we should do, but it is no longer the same subject or
view.
And now let me say that it is often surprising how much alteration
may be made by changing our position. Figs. 15 and 16 are together
an instance of this, the outline here given being made from a pencil
sketch made on the spot, whilst figs. 17 and 18 are examples of the
desirable change brought about by watching and waiting for a change
in the position of light and the condition of the river's tide.
[Illustration: Fig. 17.]
[Illustration: Fig. 18.]
Where the beginner most often fails is in taking things as they are
without pausing to consider whether they might not be improved, and
if so in what way, and then patiently searching to see if such
better way can be found.
Pictorial success will as often as not depend on the exercise of
fastidious taste, which is satisfied with nothing but the very best,
and not quite content even then.
A great deal more might usefully be said with reference to the
composition of lines if space would permit, but this general
reference may be given as a sort of summing up.
If the disposition of the lines constitutes such a perfectly
symmetrical design that it is at once recognised as symmetrical,
then it is wrong, because the artifice by which pleasing composition
is attained is betrayed, and we feel the thing to be artificial. If,
on the other hand, the lines fall so as to make the beholder
conscious of their presence, as, for instance, cutting off a portion
of the subject or presenting a one-sided appearance, again it is
wrong. _In neither case should the lines or the objects suggesting
them be felt at all until sought for, neither as being very right or
very wrong._
In art it is a maxim that the means by which the thing is done
should not proclaim itself, and hence it must apply to pictorial
photography, which is an effort after the artistic. A composition
should please without our quite knowing why, and without our being
able to see the machinery, as it were, by which our pleasurable
sensations are set in motion.
But whilst it is convenient to speak of _lines_ in the landscape, it
is only a manner of speaking, for, as we know very well,
photography, unlike pen drawing, has to do with "tones," that is,
_masses_ of light and shade. Now the general rules suggested as
regards the arrangement of lines, apply in much the same way if we
regard a picture (as we should do) as consisting of masses of light
and shade.
If when standing before a picture we close the eyes and then
suddenly open them, our attention is certain to be drawn to the
highest light or the deepest shadow, and hence, as a general rule,
whichever of these is the strongest to attract attention, that
should be in or near the principal object (indeed it will make of
itself the principal object), and should therefore be well removed
from the margins of the picture.
Refer back to fig. 8, in which the light patch of sky, the light in
the water and the two clusters of light rushes, all form competing
points of attraction, and if these are too near the margins, they
remind us of those margins, hence the improvement in effect when
these are cut away or left out.
But disposing of the highest light and deepest dark does not finish
the matter. There is a certain relative degree of lightness and
darkness between everything in nature. Moreover, colours have to be
interpreted by certain degrees of light and shade according to the
distance objects are away from us, and according to the amount of
light falling on them.
Such relative lightness and darkness is called "_tone_." The word
used in this sense has nothing to do with "tone" as applied to the
colour of a print, which colour we change by a process we call
"toning," and upon the correct rendering of relative tones so much
of the effect of a picture depends, and so much of its emotional
qualities.
Generally speaking, although there are often exceptions, the further
an object is from us the grayer it seems. White becomes less white,
and dark objects grow less dark, until in the distance both, under
ordinary circumstances, come almost to the same "tone," and we see
the distance only as a gray hazy mass.
If for a subject we have a figure of a woman by a stream of water
and we make an under-exposed negative of it, or develop the negative
to too great a density, we shall very likely have a print in which
the water and the woman's apron and cap come very much whiter with
regard to the rest of the subject than ever they appear in nature,
whilst the distance will very likely come too dark. Here we show a
disregard for the correct rendering of relative tones and the effect
is hard and harsh, unlike nature. We must therefore endeavour, both
in exposure and development and printing, to preserve relative tones
exactly as they are in nature, and constant study and observation of
nature should be carried on in order that the eye may be trained to
know how things come relatively in nature, and so be able to decide
at a glance if the photograph is good.
Ultimate success, by the way, often depends less on knowing what to
take and how to take it than on a well-trained judgment which knows
what is good or bad when we have taken it.
Whilst the mere lines or forms of objects may impart some amount of
feeling and sentiment to a scene, inasmuch as there is restfulness
and repose in the long horizontal lines of the river-side pastures,
something rhythmical in the sinuous curves of the winding stream, or
vigour and variety in the irregular forms of the rugged cliffs and
so on, yet the ideas and feelings which the picture will promote
depend more on the lights and shades, and the masses contrasting or
merging each with each.
But Nature does not always present herself in pleasingly arranged
masses, and is consequently at such times commonplace and
unpicturesque in the literal sense of the word. At such times she
will not attract the pictorial worker any more than she will when
perchance the lines and groupings are unsuitable.
The landscape which basks under the full blaze of sun, glittering
throughout every inch with a myriad twinkling lights and sharp
details, awakens no feeling akin to those which probably everyone
feels when in the twilight of evening plane after plane recedes as
one broad flat tint behind the other. Under the bright light of day
we may wonder at the richness and plenty upon the earth, we may
rejoice in that there are so many curious and pretty things to look
at, but these are like the feelings inspired by reading a book on
natural history, rather than the emotions created by the perusal of
a poem, or listening to sweet music.
[Illustration: Fig. 19.]
Compare for a moment the two photographs, fig. 19 and fig. 20.
The first is by no means an extreme case of the ordinary photograph,
and notice that although the composition is fairly good as far as
grouping goes, there is an absence of any quality which might make
one feel anything outside the bare recognition of the facts
depicted, but the second, if it be good at all, must depend for
admiration on a certain amount of sentiment which it suggests or
creates. You will notice that in the first there is no sense of
distance, and although a church tower, behind the masts of the
boats, is half a mile or so away it does not possess the "tone" and
veiling of atmosphere which would make it appear distant. Every part
of the view seems equally near, or nearly so; the eye wanders over
the whole, alighting on details here and there which interest and
amuse, yet there is an absence of just that breadth which is
noticeably present in the second example.
[Illustration: Fig. 20.]
Now let it be distinctly understood that detail, its omission or
suppression, and its introduction or sharp delineation, is not a
question of lens focus only, or even chiefly, but it is largely a
question of light. Imagine the photograph, fig. 19, with the greater
part of the detail taken out so that the quay, the houses, the
shore, etc. were just broad masses of lighter or darker tone, should
we not then get a composition which would be less disturbing, more
compact, more concentrated in interest? Is not this the case in fig.
20, in which detail is almost entirely absent? And yet detail could
not have been truthfully introduced in this photograph, because with
the light in the position it is, and in the misty evening air, _no
detail was there to reproduce_; it was the fact that objects ranged
themselves in masses one against the other, leaving room for
imagination and creating ideas that determined its selection and its
consequent portrayal.
In many cases a clear and sharp delineation of details will perhaps
be desirable, not, however, for the sake of showing detail, but just
so far as the production of the effect may require; on the other
hand, just the full amount of detail that a lens will give is by no
means always wanted.
_Lenses were not invented for pictorial purposes_, and therefore
there is no reason for concluding that what the lens gives is
necessarily right, for remember that we started with the distinct
understanding that we were merely _applying_ to a certain purpose
just so much of the photographic process as we considered we needed;
because I have the means of travelling at sixty miles an hour there
is no reason why I should not apply the same means of locomotion to
coaching a pedestrian at a tenth of that speed if I choose. It may
be said that in the two photographs referred to the comparison is
not a fair one, because so much depends on the sky. Granted that
much in the second example does depend on the sky, which is an
essential part of the picture, and indeed one cause of its very
existence, but in the other (fig. 19) the presence of clouds would
not improve the pictorial faults to which reference has been made.
As a mere record or portrayal of Old Woodbridge Quay, the absence
of clouds is as much a characteristic of its particular species, as
the clouds in the second one are inseparable from its existence.
So, but little more than half hinting at the principles involved in
the due suppression of unnecessary details, and the elimination of
undesirable objects in order to obtain breadth, and having said but
little as to the preservation of correct relative values or tones, I
must pass on.
Every corner of nature's broad expanse is, as it were, enveloped in
atmosphere, and invisible as we are commonly in the habit of
considering it to be, it affects to a greater or less degree
everything we see, and the visible atmosphere is often responsible
for some of nature's most beautiful and most appealing aspects.
Obviously then we cannot afford to leave out so important a
contributory to picturesque effect, and it is on this account rather
than on account of sharp or un-sharp detail that the question of
stops and lens apertures comes in.
Look at the image of a landscape on a moderately hazy day, as it
appears on the ground-glass focussing screen of your camera, using
the lens at full aperture--then quickly insert _f_/32, and notice
the difference. Not alone have objects near at hand and more remote
become more sharply or more equally defined, but you may also notice
that objects are _more brilliant_, and that a sense of atmosphere
has been cut out.
Compare if you will two photographs, the one made respectively with
full aperture of _f_/6 or _f_/8 and the other made with _f_/32 or
_f_/45, and provided that in the first case we have not actual
blurring to the extent of destroying form and structure, does not
the first remind you more of nature? I do not say it is so
instructive, so surprising, so dainty, or of such exquisite finish,
but is it not more reminiscent of the _effects_ we remember to have
seen and _felt_ in nature. It is not the function of this article to
say to what optical laws this difference is due, and yet the student
may expect to receive something by way of practical working
instructions.
My recommendation is then to use a single landscape lens or the
single combination of a doublet, and in starting to use the full
aperture.
With this it may be that when the foreground is moderately sharp,
trees more remote are so ill defined as to appear as a collection of
little blots and irregular patches. Whilst sharp detail in all
places may not be productive of pictorial effect, yet the extreme
opposite will be displeasing in another way, and it will be best to
secure just _so much definition and no more_ as shall save the
representation from appearing to have been wilfully put out of
focus--once let the destruction of detail be obvious and we betray
the artifice by which we are working, which is just what we should
avoid.
In the case just supposed then, we may now introduce the first stop,
simultaneously racking the lens in a little until we get middle
distance without unpleasantly obvious blurring. The foreground may
be a little out of focus, and in practice I find it is rather
helpful to general effect if detail is sacrificed more in the
foreground than in the middle distance.
This I believe is contrary to the teaching of many, but my feeling
is that with a sharply defined foreground the eye is attracted and
the interest so far arrested, that it is difficult to travel further
and enter into the poetry and sentiment of the scene beyond.
Wide-angle lenses have a double disadvantage, shared in part by
so-called rapid rectilinear doublet lenses. In the first place they
flatten the view, bringing distant planes to appear as near as the
nearer ones, and by including a comparatively wide angle they bring
into the plane of the foreground, objects so near that they appear
out of proportion, and hence proportions are false when judged as
the observer must judge by the standard of visual perspective.
A long-focus, narrow-angle lens necessitates a camera which racks
out to a considerable length, and probably a greater extension than
any camera in the ordinary way can give, would be an advantage on
some occasions.
Passing reference has been made to the interpretation of colours in
nature in their true relative value of black and white.
If we have a subject in which brilliant orange-coloured rushes in
autumn are seen as glowing bright against a background of dark blue
water, and the rushes made still more golden of hue by the ruddy
rays of a sinking sun, a difficult case is before us.
Such a case I remember very well in the south of Devonshire, close
to what is known as Slapton Ley. It was late afternoon in November,
and from over the rounded hills behind me to the westward, the
declining sun sent warm red rays on to the belt of faded reeds which
stretched out into the expanse of the still land-locked water of the
Ley--a great sheet of fresh water which placidly lay under the
shelter of the bank of shingle which alone separated it from the
ever-restless sea--placidly listening to the ceaseless voices of sea
music, and at this particular hour reflecting the sky deep blue and
of almost leaden hue--just above the bank rose the full moon, orange
in tint, on a background of blue-green sky--the yellow reeds,
kindled into glowing amber tints by the sun's rays, flamed out from
the deep blue water--yellow the shingle bank against the blue water
and green-blue sky, deeper yellow the moon as it rose from out the
sea. So grand a scheme of colour that by its side the essays of the
most daring painter might well seem feeble, so exquisite a poem that
the intrusion of the photographer, analysing the values and tones
and calculating his powers of reproduction seemed like sacrilege. In
the main it was yellow, orange-yellow, and red standing out as
luminous against the deep blue of water and only a little less blue
sky. It was gorgeous non-actinic colour appearing as _light_ against
a highly actinic but _darker_ colour. The consequence of an
indiscreet exposure with an ordinary plate might be anticipated to
produce _dark_ rushes against a _pale grey_ background of water, and
so probably the very effect we were minded to secure, reversed and
dissipated.
This is an extreme case, perhaps, but throughout the whole range of
nature the contrasting and blending of adjacent colours is so subtle
a thing that I should feel one were throwing away at least a
possible advantage by not using colour-corrected or isochromatic
plates on nearly every occasion, and in order to get the full
advantage of isochromatic plates, I should consider the addition of
a yellow screen an essential.
The rapidity of one's plates, isochromatic or otherwise, must be
governed entirely by the nature of the subject, as also to some
degree must be development and subsequent printing.
In every case I would endeavour to get a comparatively thin
negative, with even the portions representing deepest shadows
slightly veiled. "Clear glass shadows" is an enormity and an outrage
both of science and art; equally are solid high-lights to be
shunned. With modern printing methods it needs much less than actual
opacity in the negative to produce white paper, and if the picture
requires any part of it at all to appear as quite white, no subject
will need more than the very smallest region to be so. A general
softness and very subtle gradation, with a total absence of
"sparkle" and brilliancy in the negative, will yield by at least
most processes the most suggestive print, bearing in mind that
delicate gradations suggest atmosphere, and atmosphere is one of
nature's most precious qualities.
Whilst plain salted papers sensitized with silver present
possibilities not yet sufficiently exploited, yet until such time
that something more entirely satisfactory in all respects is given
us in silver papers, platinotype and carbon, and perhaps also gum
bichromate will be the processes most suitable for our purpose.
Personally, platinotype has been the favoured medium, being, as I
believe, more ductile and more amenable to various methods of
control than is generally recognised.
And leaving much more of importance unsaid than space limits admit
of my saying, I must leave it.
_A. Horsley Hinton._
_Architectural Photography._
[Illustration]
To the majority amateurs, the photographing of architectural
subjects presents considerable, and in many cases apparently
insurmountable difficulties. Undoubtedly there are difficulties to
be grappled with, but they are neither so formidable nor so
numerous, but that any ordinary photographer with the average amount
of common sense can master them be he so minded.
Unfortunately there are a great many who take up photography as an
amusement to whom the slightest departure from the ordinary routine
presents a difficulty. It is however to the amateur photographer who
desires to be able to portray architecture, be it either of our
cathedrals, churches, historic mansions, or places of personal
interest, and at the same time wishes to be able to do the subjects
fair justice, that it is hoped the following particulars may be of
some service.
To the beginner taking up this or indeed any branch of photography,
size is of course a great consideration either from the weight
carrying or pecuniary point of view. Another reason is the fact that
young photographic workers have an idea that the smaller the plate,
the easier the working. Sound though this reasoning may appear,
nevertheless it is not entirely correct.
As a matter of fact all things being taken into consideration the
larger the plate up to 12 × 10 or 15 × 12 employed the more rapidly
will the worker progress.
Large plates, especially in architectural work, tend to make the
operator more careful and conscientious when out with the camera;
and even more so when in the developing room. So much more can be
done with a large plate than with a small one; the use of a large
plate moreover checks the common failing so prevalent among amateurs
of rushing work and recklessly using plates.
Taking all things into consideration, I would strongly recommend the
whole plate or 10 × 8 camera to the student taking up this branch of
our art.
In selecting a camera purchase a front extending one with bellows
only slightly tapering. See that it has both rising and cross
movement to the front, and also that the amount of movement in each
case is a not too restricted one. Makers, unfortunately, do not give
sufficient attention to this matter, the usual rise allowed being
very slight whereas it should be at least equal to one-third of the
longest way of the plate; even more than this is advantageous if it
can be obtained. By the rise I mean the amount of upward movement
that can be obtained, the lens being in the centre before starting.
The cross-front should have a movement of about one-quarter of the
length of the plate each way.
It may be useful to know that a little more rise can be obtained by
the placing of the lens above the centre of the cross-front;
reference to the photograph of camera will explain this matter more
fully.
The swing-back should be a practical one, working from the centre,
and capable of being swung either to or from the lens.
In many of the cheaper front extension cameras it is not possible to
use the swing-back when tilting the camera down, only when tilting
upwards. The swing-front, although not an absolute necessity, is
undoubtedly a movement possessing great advantages, especially when
the front is raised rather high, and one is using a lens of limited
covering power. This movement should be acquired if possible.
The camera should possess double extension, focussing by rackwork,
and having a reversing back so made that it will fit on all ways; it
is then possible to draw the slide shutter out in any position.
In selecting a tripod stand purchase one of the kind known as the
sliding leg variety, two-fold is better than three, giving greater
sliding power. The top of stand should be as large as possible; this
is preferable to a turntable, as this piece of workmanship is seldom
rigid after a little use, and some difficulty is experienced when
trying to spread the legs out rather wide. A two-fold Ashford stand
is as good as any on the market.
The blocks herewith illustrate the kind of camera used by myself,
and with the exception of the turntable, which is not a great
success, it answers all requirements.
In the selecting of suitable lenses a great deal will depend upon
the inclination of the purchaser and the depth of his pocket.
There is such a great variety upon the market at the present time,
that to the young photographer the buying of the right lenses is
somewhat a difficult problem.
[Illustration]
[Illustration]
The Zeiss series are undoubtedly the finest obtainable and for
architectural work are unrivalled, possessing great covering power,
good marginal definition, and in fact very fine definition all over
the plate. The lenses of this series, although quite new, have met
with great favour amongst architectural workers.
They work at an aperture of _f_/18, but I understand that they can
be opened to _f_/16 and numbered on the _f_ system. As regards their
relative working capabilities they give about the same picture at
_f_/32 that the majority of wide-angle lenses give at _f_/64.
The Goerz anastigmats are also another very fine series but do not
give anything like the covering power of the last mentioned, and
moreover are nearly double the price. Their special merit is that
one can work at _f_/8 or _f_/11, and get a picture sharp up to the
edges. Taylor, Taylor & Hobson also make a good wide-angle lens,
possessing great covering power and at a moderately low price. With
one of their nine inch lenses I have covered a plate 12 × 10 inches.
[Illustration: "GATHER THE ROSES WHILE YE MAY, OLD TIME IS STILL
A-FLYING." ALEX. KEIGHLEY.]
For a whole-plate camera, a useful battery would be a 5 inches,
7-1/2 inches, 9 inches and 12 inches; for 10 × 8, 7 inches, 9
inches, 10-1/2 inches and 14 inches. The three last in each case are
the most useful.
Having selected the lenses, another very important point and one not
to be decided hastily is the question of levels. Four are required,
two circular and two ordinary. They are placed as follows: Fix the
circular levels, one on the baseboard near the front of the camera,
the other on the top of the back part of camera. The other two
should be placed one on the side of the back part and the other on
the back of camera just under the reversing back. Care must be taken
to purchase slow moving levels as some work so quickly that it is
next to impossible to level the camera with them, and as this is one
of the most important points in the whole business, too much care
cannot be taken in selecting and fixing the right kind of level.
[Illustration]
The focussing screen should be ruled as accompanying diagram. This
will divide the screen into inch squares, working from the centre,
and will considerably assist the photographer in "sizing his subject
up."
One other thing required is a set of clamps for binding the tripod
legs together. These are, I believe, made by George Mason, of
Glasgow, but any dealer will procure them for you.
The use of the right kind of plate constitutes a very important
factor in the production of a satisfactory negative, particularly in
this branch.
Owing to the greater difficulty experienced in developing extra
rapid plates, one generally sees the slower variety recommended. No
hard and fast rule can however be laid down. To gain the best
result, the plate must be suited to the subject.
For instance, in a very dark interior in which heavy black shadows
predominate, many of them appearing much darker than they really are
owing to their close proximity to a strong light, the quicker the
plate used the better. This tends to break down the harsh contrasts,
and at the same time the shadow detail is considerably better
rendered.
On the other hand, working in a light interior or one which is flat
owing possibly to the large amount of light present, a slower plate
can be used with advantage, and, providing the exposure is
sufficient the result will be all that is wished for.
Exteriors, particularly those in sunshine, should be photographed on
a fairly quick plate. Slow plates, although good, do not yield
nearly such good negatives, and unless very fully exposed give
excessive hardness.
Taking this class of work all round, the quick plate is the more
useful of the two and is undoubtedly the best for interior work,
particularly such interiors as one meets in our English cathedrals.
For all subjects possessing strong high-lights, such as windows,
stained or otherwise, rapid plates combined with a suitable backing
composition yield the best results, and I would impress upon the
reader the fact that no plate should ever be placed in a dark slide
without being covered at the back with a suitable composition for
the prevention of halation.
[Illustration]
The value of this agent is distinctly demonstrated by the
accompanying illustrations, and I would point out the fact that the
negatives were both developed with the utmost care. The unbacked
plate was so developed as to prevent the appearance of halation as
much as possible, and it will be noticed that all portions of the
photograph, other than that where halation has occurred, are nearly
as good in the unbacked as in the backed one.
Having obtained all the apparatus and materials, a very good subject
to begin on and one giving good opportunities for the exercise of
the various movements connected with the camera, etc., is a general
view of the choir in some cathedral or church near at hand.
Having erected the camera, the next thing is to decide upon the most
pleasing point of view.
Speaking from my own experience I would advise the shifting of the
camera either to the right or left, so that the centre aisle is
thrown slightly in perspective. This tends to give a much better and
decidedly more pleasing effect to the resulting photograph. Of the
two sides, moving to the right seems to be the best. The next item
is the fixing of your ground line, this must be so arranged that it
is quite clear, not obstructed by the backs of chairs, etc., which
look very badly if left standing. Personally, I have generally found
it necessary to move one or two rows of chairs so as to make the
ground line myself.
In adjusting the height of the camera from the ground it is well
never to exceed six feet. Five feet to five feet six inches is the
most useful height. This will give a photograph in which the point
of sight is the same as that of the person actually viewing the
subject.
The placing of the camera on step ladders, chairs, or other
supports, so as to overlook objects in the immediate foreground is a
practice to be condemned, giving results very rarely pleasing and
always bad from the sightseer's point of view.
Having settled upon the point of view and the lens to be used, the
student should then roughly focus the image. Notice the amount of
subject on the plate and how much rise is required.
If having a camera such as described, the rise is easily
accomplished and the camera can then be truly levelled up. Care
should be taken over this as unless you have the camera exactly
level you cannot expect a true picture. The bubbles of the levels
should be _exactly_ in the centre, _a little bit out will not do_.
[Illustration]
If it is found that the rising front fails to give the amount of
subject required, recourse must be made to the swings, and it is
here that the swing front triumphs over the swing back.
To swing the back necessitates the shifting of the camera and tripod
stand, and at once throws all the levels out of gear. Then comes
re-focussing, etc. Sometimes this will have to be gone through five
or six times before the desired amount of swing has been achieved.
Owing to the re-focussing required every time the camera is moved it
is very difficult, especially for the beginner, to rightly estimate
the amount of rise required.
With the swing front the desired amount of rise is attained easily
and quickly, and it can be worked with the head still under the
focussing cloth, which is a great convenience. At the same time the
baseboard and back of camera always remain level.
After gaining the correct amount of rise the sides of the subject
should be considered. A golden rule to remember in this class of
work is when you show a column, show the base of it, and always
start the sides of plate with either half or three-quarters of a
column. It looks very queer to see the bend of an arch wandering
away out of the side of the picture without any apparent support. In
arranging the sides it is usual to have a preponderance of subject
on the opposite side to which the camera is, and to start that side
with a column. Sometimes the subject fails to fit the plate nicely,
in that case it is better to trim the print than to have
uninteresting features present.
Of course a great deal depends upon the personal taste of the
worker, what one man considers right another will rebel against; so
although I advocate the use of columns to fill the sides of the
plate it does not follow that that is the one and only method of
photographing these subjects.
The student having carefully gone into these matters and arranged
the subjects to suit his own satisfaction the question of what point
to focus for arises, and indeed in very dark interiors the question
of focussing anything at all comes in. A method I use myself is to
roughly divide the distance from the camera to the farthest object
in half, and then to focus midway between the camera and the middle
of the subject. Then stop down the lens until the most distant
object is sharp. In practice I have found this rule so good that I
can recommend its adoption for all subjects, and if carried out
correctly will always result in the production of crisp negatives.
Exposure is not a very difficult thing to overcome. Arrange the
focussing cloth well over the head, open the lens out to its largest
aperture and remain under the cloth until you can see the image
distinctly all over the plate. Then without uncovering the head
proceed to slowly stop down until you can only just see the image
all over the plate. Now using a plate of the rapidity of Barnet
extra rapid, an exposure of ten minutes will yield a satisfactory
fully exposed negative.
The varying exposures for other plates and stops are easily
obtained. For instance you find the image can just be seen all over
at _f_/32 and you wish to use _f_/64 The exposure will be forty
minutes.
After having used this method for over seven years, and having
invariably found it correct, I can unhesitatingly recommend its
adoption, and if used with a little common sense the worker will
seldom suffer from his plates being either badly under or
over-exposed.
In photographing side aisles, transepts, or long rows of pillars,
the worker is often troubled by the unnatural way in which the floor
runs up. This is more especially noticeable when there are no
prominent objects in the immediate foreground. A considerable amount
of this can however be overcome by the lowering of the camera to
about three feet from the ground. It is here where the sliding legs
of the tripod stand become of service.
I would ask the student always to use the longest focus lens
possible, consistent with the effect desired.
The use of extreme wide-angle lenses has had a disastrous effect
upon the public taste in respect to architectural photography due
principally to the abortions one sees exposed for sale in the shop
windows of our cathedral cities.
It should be seldom necessary for the amateur to use very wide-angle
lenses. Of course, when it is a question of getting a detailed
photograph in a confined situation a wide-angle lens is of great
service. But it is when you see the whole length of a cathedral
photographed on a whole plate with a five inch lens that the fault
is so noticeable.
In photographing exteriors great care should be taken in the placing
of the camera in a suitable spot. Try and so arrange it that the
short side of the building does not run off too violently, indeed,
it is often much better to leave out a portion of the subject rather
than to cram the whole subject upon the plate.
General views are much better if photographed when there is a little
sunlight. This gives to the subject a sharp, clean-cut appearance.
Details on the other hand are better if photographed in a subdued
light and slightly over-exposed.
In focussing very high subjects some difficulty will be found in
getting bottom and top in focus at the same time, especially if the
lens be strained by either altering the back or front of the camera.
The best place to focus is a little way above the centre of the
screen, so that when stopped down the bottom of the building is
quite sharp. A slight softness towards the top of the subject is
scarcely noticeable in the final print.
The exposure of exteriors varies between three seconds at _f_/64 to
ten minutes, and no correct guide can possibly be given. To the
beginner a Watkins' exposure meter will here be of some service.
If people are continually passing and repassing stop the lens down
to _f_/64 and give as long an exposure as is possible; this will as
a rule completely obliterate them. I have found that an exposure of
from ten to twenty seconds entirely destroys all trace of moving
objects.
Another method of making an exposure where there is much traffic
past the building, and perhaps people standing about whom you cannot
very well ask to move, is, to break the exposure as many times as
possible. Expose for two seconds, then wait until the traffic has
somewhat altered; then give another two seconds and so on until
finished. By this means I have been able to photograph buildings in
the centre of a crowded street or thoroughfare without a trace of
anybody showing.
It is often interesting for the student to be able to successfully
tackle the photographing of drawing-room, ball-room, or other
apartments either of his own or friends' houses.
This work is considerably more difficult than it seems; and it is in
such subjects that the taste of the operator becomes manifest. A
great deal depends upon the point of view chosen and also upon the
arrangement of the furniture.
If a long room, the camera should be placed at one end at about a
quarter of the width of room away from one side and from the end
wall. Keep the camera parallel with the sides of the room and use
the sliding front so as to obtain more of the opposite side of the
room. This will give the ceiling a true square appearance and the
side of the ceiling will not run off with an unpleasing effect.
In some subjects it is perhaps necessary to include one or more
Showing first 200,000 characters. Full text: gutenberg.org/ebooks/40468