was taken will serve equally well to enlarge it, and in the abstract
the statement is perhaps not inaccurate. But assuming that a lens of
a focus equal to about 1-1/4 times the base of the plate has been
used, it will be found that better results, both in regard to
definition and equality of illumination, will be obtained by
substituting a lens of rather longer focus, for example a half-plate
lens for enlarging from quarter-plate negatives. This, although
applying to both methods of working is particularly desirable when
enlarging by artificial light, for an objective of small diameter
and short focus cannot possibly pick up or receive the whole of the
cone of rays proceeding from the condenser. A reference to Figs. 7
and 8 will explain why this is so. In Fig. 7 we see what happens
when a lens of too short a focus is used, but when one of longer
focus is substituted, the whole of the cone of rays passes through
and is utilized (Fig. 8). In selecting a lens one should be chosen
which has a sufficiently large diameter to permit the apex of the
cone of rays from the condenser to pass through. This point will, of
course, vary with the degree of amplification, and in order to
obtain the best results optically, the distance of the light from
the condenser must be carefully adjusted in every case, and a clear,
evenly lighted disc obtained before inserting the negative to be
enlarged.
[Illustration: Fig. 7.]
[Illustration: Fig. 8.]
With regard to the type of lens, one of the rapid rectilinear form
will answer well. A portrait lens is often used on account of the
brilliancy of image, but although it answers well for enlarging
portraits, the roundness of its field makes it less suitable for
landscapes unless it is considerably stopped down. If the very
finest results as regards definition are required, then one of the
now numerous flat-field lenses should be used. The writer can from
practical experience speak well of the Ross-Goerz and the Cooke
lens. The latter is perhaps preferable for working with artificial
light on account of the larger diameter of the back lens. Wide-angle
lenses, on account of their small aperture and short focus, are not
suitable for use with a condenser, both for the reasons given, and
on account of the difficulty in focussing owing to the small amount
of light transmitted. When daylight is used, however, there is less
objection to their employment.
[Illustration: Fig. 9.]
Before leaving this part of the subject it should be noted that in
regard to preserving the parallelism of its parts the same care in
erecting and fitting up the enlarging lantern must be observed, as
was insisted upon in the description of the apparatus for daylight.
It will be found convenient, therefore, to mount the lantern on a
base similar to that upon which the easel rests, so that both may
move on the same rails. The easel described for daylight enlarging
will serve equally well for working by artificial light. The
complete apparatus is shown at Fig. 9, which is a reproduction from
a photograph of the apparatus constructed and used by the writer.
THE NEGATIVE.
In general practice one may find it necessary at times to enlarge
from negatives of very dissimilar types, but there is no reason,
when the negatives are to be produced with the special object of
subsequently making enlargements from them, why care should not be
taken to make them of a suitable character. Thin delicate negatives
should be enlarged by artificial light; dense, strong ones by
daylight. If the negatives are very strong it will be difficult to
produce soft and well-graded enlargements with a weak illuminant,
the light not being sufficiently intense to properly penetrate the
high-lights. A soft and clear negative, with good gradation, fully
exposed, and neither exhibiting patches of clear glass shadow devoid
of detail, nor of hard impenetrable high-light, will be found most
suitable. Fog should be avoided, as also should the yellow stain
produced by pyro when improperly used. Not that the pyro developer
is unsuitable, for if sufficient sulphite is used, and the quantity
of pyro kept down, negatives of very beautiful quality for enlarging
purposes may be produced. Great care should be taken to avoid
bubbles, stains, scratches, or any kind of mechanical defects, as
such when enlarged become painfully obtrusive, and spoil the effect
of the best work. It will be found a good plan to bind the edge of
the negative before enlarging it with a strip of lantern slide
binding, so as to cover the clear glass rebate mark. If this be
omitted the margins of the enlargement may become fogged by the
lateral spreading action of the light. No hand-work should be
attempted on the original negative, for any such treatment will
become painfully apparent in the enlargement. If retouching be
deemed necessary, it should in the case of a direct enlargement be
executed upon the print itself, or upon the enlarged negative or
preferably upon the enlarged transparency, when that method of
reproduction has been adopted.
DIRECT ENLARGEMENTS.
The following concise instructions for enlarging upon bromide paper
will apply equally to the daylight or artificial light methods of
working. In the first case the negative is placed in the dark slide
of the camera, both shutters being drawn fully out. The camera is
then put upon the shelf close up against the opening in the shutter,
as shown in Fig. 3, any light creeping in between shutter and camera
being blocked out with the focussing cloth. If the enlarging lantern
is used the negative will be placed in the carrier, just in the same
way as a lantern slide, with the film side towards the enlarging
lens. Now the first difficulty that will be experienced will be to
get the enlarged image of the required size. It will be well to
content ourselves at the outset with a moderate degree of
enlargement, say from 1/4 plate to 12 × 10, and when proficiency is
acquired, larger sizes can be attempted. At first we shall probably
not succeed in getting any image at all. In adjusting the various
parts of the apparatus we shall find the work easier if we remember
that the nearer we place the lens to the negative the further will
it be necessary to move the easel from the lens, and the greater
will be the enlargement. A useful table of enlargements will be
found in the "British Journal Almanac," showing the distance of lens
from negative, and negative from paper, for almost any required
degree of amplification.
Now it will be found much easier to focus the enlarged image by
looking at it through a piece of finely ground glass, than by
receiving it on a piece of card or paper, and the adoption of the
easel plan of focussing previously described will enable this to be
done. The ground surface of the glass (which must be of the same
thickness as the piece behind which the paper is to be exposed)
should be away from the lens and towards the person focussing, when
it is placed in the carrier of the easel, it being retained in
position with the spring S., Fig. 2. Focussing must be carefully
performed, and is effected by sliding the easel to and fro upon the
runners, and which should have been previously rubbed with
blacklead.
Bromide paper is made in several varieties, such as smooth, rough,
snow-enamel, cream crayon, etc., and is put up either in tubes, or
packed flat. The latter is decidedly the more convenient, it being
somewhat difficult to take the curl out of paper that has been
rolled. The choice of paper is a matter of taste; for landscape work
the rough paper or the cream crayon will perhaps be found most
suitable. For finer work, and some classes of portraiture the enamel
will prove effective. Rough paper is better for strong broad
effects, smooth for more delicate work and the rendering of fine
detail. The coated side may be distinguished by its tendency to curl
inwards. The easiest way of exposing it is to procure two pieces of
patent plate glass of the same thickness as the focussing glass,
sandwich the sheet of paper between the two, and secure with strong
elastic bands. This will hold it quite flat during exposure, and
will not disturb the actinism of the lens or impair the definition
of the enlargement.
DEVELOPMENT.
This part of the work of producing an enlargement will only be
lightly dealt with, as the subject is fully treated elsewhere in
this volume. The writer prefers the ferrous-oxalate developer for
bromide enlargements to any of the more recently introduced
developers, but as it requires more skill and judgment to employ it
with complete success, beginners may find it better to use amidol or
metol, either of which when properly used gives excellent results.
Hydrokinone we do not recommend for this purpose owing to its
tendency to give rusty blacks in the event of over-exposure, or
undue hardness if it has been too short. With amidol a pure delicate
black is easily obtainable, and it is moreover a very simple
developer to use. Our own plan is to employ a weak solution and give
a full exposure, and by these means we find no difficulty in
obtaining good gradation and pure blacks. The dish used for
development must not be used for other developers or stains will
probably occur. Although a quick appearance of the image is usually
a characteristic of amidol, no trouble will be experienced when the
developer is used in the way we advise, for the picture will be
found to develop slowly and regularly, and gradually grow in
strength. Quick development by this method would be an indication of
over-exposure. A correctly exposed enlargement should take about ten
minutes to develop. One stock solution only is necessary. It will
keep indefinitely.
Sulphite of soda 1 ounce.
Citric acid 20 grains.
Distilled water 40 ounces.
Potassium bromide 15 grains.
To each ounce of the above add, just before using, three grains of
dry amidol. The exposure must be accurately timed. It is, however,
impossible to give useful information on this head, unless such
varying factors as the rapidity of the paper, the intensity of the
light, the aperture of the lens, and the degree of enlargement are
known. The best plan is to cut one of the sheets of bromide paper
into twelve strips, and on these make several test exposures,
carefully noting the duration of each. It is better (at any rate for
a beginner) not to vary the constituents or strength of the
developer, but to increase or diminish the exposure until a good
result in colour and tonality is obtained. By entering full details
relating to the production of a successful enlargement in a
notebook, great exactitude in working will be obtained, and there
need be little or no waste of material when additional enlargements
have to be made from the same negatives at a future time.
[Illustration: DRIFTING STORM CLOUDS. W. THOMAS.]
A glass dish, though expensive, is very suitable for developing, for
being flat-bottomed a minimum of solution can be used, and moreover
if the dish should be dirty, the fact is at once apparent. The
exposed paper should be soaked in water for a few minutes until
uniformly wetted, and any air-bells removed with a camel-hair brush.
The water is then poured off, and the developer applied in an even
wave, so that the whole of the paper is covered uniformly and
quickly. The image will appear slowly, and gradually gain in detail.
When all the detail has appeared it may still appear lacking in
vigour and contrast, but this will come if sufficient time be
allowed. _Development should not be stopped until the print is of
the full strength required_, but it is not advisable to allow it to
become much darker than it is desired to appear when finished,
because there is very little loss of strength in the fixing bath.
If the image flashes out immediately upon the application of the
developer, the paper has been over-exposed. A strong dose (one or
two drams) of ten per cent. bromide added to the developer may help
to save it, but the enlargement will probably look poor and flat and
of bad colour when finished. If the picture appears very slowly, and
refuses to gain in strength, under-exposure is the cause, and two or
three drams of a ten per cent. solution of sulphite of soda may
improve matters, but as a rule the most satisfactory plan will be to
make another exposure. With regard to the strength of the developer,
that given is very suitable for negatives of normal density, but
some papers may require a little more amidol, the appearance of the
finished enlargements will guide the reader in regulating the
quantity to suit the particular paper with which he may be working.
The enlargement should be washed in plenty of running water from the
tap to arrest development, and then fixed in:--
Hyposulphite of soda 4 ounces.
Water 20 "
A quarter of an hour should be allowed for fixation, but it is
better to use two baths, giving ten minutes in each. After washing
in running water for a couple of hours they may be hung up by one
corner to dry, or pinned down to a blotting board.
Enlargements produced in the manner described should be of a pure
engraving black colour, and if they are mounted upon _pure_ boards
with _freshly_ made Glenfield starch, they should prove permanent.
Enlargements are frequently toned to various shades of brown and
red, generally by the employment of the uranium-toning bath.
Although the colours so obtained are often very artistic and
pleasing, no reliance can be placed upon the permanence of an
enlargement so treated, and the writer strongly recommends that when
warm coloured prints are desired, an enlarged negative should be
made and prints made therefrom in carbon, silver, or sepia
platinotype.
ENLARGED NEGATIVES.
The production of an enlarged negative presents no difficulty that
need deter any careful worker from attempting the work. No
additional apparatus to that already described will be required, and
either day or artificial light may be employed. In the first place
a transparency must be made from the small original negative. It
may be made either by contact or in the camera, preferably the
latter as then the acme of sharpness will be obtained. If, however,
the reader is acquainted with the carbon process he cannot do better
than make a carbon transparency, for such are specially adapted for
the production of enlarged negatives. Many, however, will prefer to
make the transparency on a bromide plate, and as this is the part of
the process which requires the greatest amount of care, and as _in
fact_ the _quality of the enlarged negative will entirely depend
upon the character of the small transparency_, it is necessary to
deal with the matter somewhat in detail. Preconceived ideas of
quality based upon the appearance of a good lantern slide must be
put aside, for that is not at all what is required. What is wanted
is a transparency in which every possible detail existing in the
negative has been reproduced, and which in comparison with a lantern
slide would look rather flat and over-exposed. Every possible
precaution should be taken to avoid granularity or coarseness of
image, therefore a slow plate is almost essential; plates coated
with lantern-slide emulsion are now obtainable, and will be found
very suitable. A full exposure should be given, and a weak and
well-restrained developer employed. These conditions tend to the
production of the qualities desired. Warm coloured transparencies so
produced generally have a finer grain than those developed to a
black or colder colour, but unless the colours produced are fairly
uniform, considerable variation in exposure when making the enlarged
negatives will be necessary, and for this reason it would perhaps be
better for the beginner to aim at the production of good black
transparencies possessing the qualities indicated.
The small transparency, having been fixed, washed and dried, should
be edged with black paper to prevent any subsequent fogging of the
plate, by the lateral spreading action of the light. It is then
placed in the enlarging apparatus, just as in the case of a
negative, and carefully focussed. This operation must be very
carefully performed. The writer uses a thin and very sharp negative
of an architectural subject to focus with, afterwards substituting
the transparency which is to be enlarged. Landscape subjects,
consisting chiefly of foliage, are seldom critically sharp, and it
is then difficult to secure a sharply-focussed enlargement. The
remainder of the operation is extremely simple. In the place of the
ground-glass screen (which in this case should have its rough or
ground side nearest to the enlarging lens) a slow dry plate is
placed, backed with a piece of cardboard covered with black velvet
to avoid reflections and possible fog. The exposure should be full,
and a weak developer employed. Trial exposures may be made on
quarter-plates, coated from the same batch of emulsion, which the
manufacturers will willingly supply, if the purpose for which they
are required is made known. Pyro will be found the most suitable
developer, but it should contain a full proportion of sulphite, and
not be too strong. Exposure and development should be so adjusted
that by the time every possible detail has been developed up, the
plate will not have become unduly dense. If expense has to be
considered, a piece of slow smooth bromide paper may be substituted
for the large dry plate in which case the result will be an enlarged
paper negative. For large sizes, 15 × 12 and beyond, the latter is a
very economical method of working, and the negatives will be found
to yield most artistic prints, and if the operations have been
carried out as described, and the prescribed conditions carefully
observed, the grain of the paper will not show obtrusively or
unpleasantly in the prints.
An alternative method of working, and one which admits of a large
amount of control over the ultimate result, is to make in the first
place a large transparency of the full size that the enlarged
negative is desired to be. All the precautions upon which stress has
been laid should be observed in regard to the choice of plate,
developer, etc.; but in this case the enlarged transparency may be
given a little more vigour and sparkle than would be desirable if
the other method of reproduction were adopted, though in this the
reader must be guided by the particular effect which he may be
seeking to produce in his prints. For this purpose pyro will be
found to be the most suitable developer, in that it permits of a
large amount of control. From the large transparency a negative is
produced by contact printing either upon a plate, or upon a piece of
bromide paper.
The great advantages of the latter mode of working are the
facilities which are afforded for retouching or working upon the
large transparency. Negative retouching is always a difficult
operation to an amateur, for he cannot see the effect of his work
until he has made a print; whereas, in retouching a transparency the
effect produced by each stroke of the pencil or brush is at once
apparent. In the space at disposal it is not possible to describe
the various ways in which improvements can be effected. First there
are the chemical aids of local intensification or reduction. Then
much may be done by the judicious use of a pencil, but the part to
be retouched must first be lightly rubbed with a little retouching
medium in order to make the pencil bite. In extreme cases the back
of the negative may be covered with tissue paper upon which a stump
and chalk may be used _at discretion_.
The novice must not be disappointed with the appearance of his
enlarged negative when it is finished, nor should he form an adverse
opinion of its printing qualities until he has made a print from it.
Confessedly an enlarged negative generally presents a different
appearance to one that has been taken direct, and may even seem to
lack some of those qualities that are commonly regarded as essential
to perfection, but if the final result, the picture, comes up to our
expectations, we may surely dismiss any lingering doubts as to
whether the enlarged negative conforms to certain preconceived
notions of technique, and it should be enough for us to know (and
the fact is incontrovertible) that some of the finest and most
artistic photographs ever shown owe their existence to this method
of production.
_John A. Hodges._
[Illustration: Walberswick. By Rev. A. H. Blake.]
_P.O.P._
[Illustration]
The three letters "P.O.P." are now so widely understood as referring
to the Gelatino-Chloride Printing-Out class of Papers that it may be
said that P.O.P. is known to many who are not acquainted with the
fully-written name of this class of productions.
Also it should be mentioned that when these papers are spoken of as
gelatino-chloride papers it is not to be concluded therefrom that
chloride of silver is the only silver salt present. What they do
actually contain is probably only known to their respective
producers. But generally speaking, it is enough to say that so far as
the ordinary consumer is concerned, the family resemblance is so
strong and chief characteristics so general that the following
directions for using them may be held as generally applicable to the
various well-known brands now on the market. At the outset, however,
it will be convenient to note that for the purposes of manipulation
we may roughly group them into two chief classes--_viz._, the matt
(probably from the German word "matt," _i.e._, dull) and the glazed,
glossy or enamelled. The latter comes to us with a highly glazed,
_i.e._, shiny smooth surface, the former being slightly rough, of a
surface and texture somewhat like that of very finely ground glass.
_Care of the Paper._--The paper is sent out either in the full-sized
sheet, measuring about 24 × 17 inches, or in smaller cut sizes,
suitable for the usual 1/4, 1/2, 1/1 plate and other popular
dimensions of plates. Compared with albumenized print-out paper,
P.O.P. is more sensitive to light; therefore, some care must be
taken to avoid needlessly exposing it to the influence of daylight
or strong artificial light. For example, the printing frames should
be filled as far away from any window as possible, and the prints
examined from time to time either by gaslight or as feeble daylight
as possible.
In handling the paper--cutting it up, etc.--care must be taken to
avoid touching the sensitive surface with the fingers in any case.
The touch of a moist or hot finger is very likely to produce a mark
or stain which is usually irremovable. The paper should be protected
from damp, excessive heat and impure air. If kept _rolled_ in a tin
tube or _flat_ under pressure in the original packages, it will keep
a considerable time--_i.e._, longer than ordinary albumenized paper.
_Printing_ is done in the usual way. Strong diffused light reflected
from the sky or clouds usually gives a better print than direct
sunshine. In case, however, of a thin flat negative--_i.e._, one
with insufficient contrast--good results may sometimes be obtained
by covering the printing frame with a sheet of green glass and
printing in moderately strong sunshine. In hot summer sunshine it is
as well to cover the green glass with a sheet of tissue paper or
fine-ground glass. Care must be always taken when printing in
sunshine or very hot weather to see that the negative itself does
not get too warm, or the paper may stick to it. In this case the
print is of course lost, and the negative, unless varnished, is also
probably seriously damaged by silver stains, which are very
difficult to remove. Printing should not be carried quite so far as
in the case of ordinary albumenized paper because in the subsequent
operations of toning, etc., not so much strength is lost. The same
care as regards shielding from light, etc., should be given to the
prints after they leave the printing frame. They may be proceeded
with at once or kept for some days before being toned, etc., but if
this is done the prints should be kept under pressure. Some workers
have thought that the light action goes on, "continues" in the print
after it is removed from the printing frame. This, however, is not
the generally received opinion.