PhotoHistory

From: THE BARNET BOOK OF PHOTOGRAPHY

How to make Enlargements (part 2 of 2)

By John A. Hodges, 1898

THE CHOICE OF THE LENS.

It is commonly stated that the lens with which the original negative 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. When a lens of too short a focus is used only part of the available rays are intercepted, but when one of longer focus is substituted, the whole of the cone of rays passes through and is utilized. 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.

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 focusing owing to the small amount of light transmitted. When daylight is used, however, there is less objection to their employment.

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 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 Figure 3, any light creeping in between shutter and camera being blocked out with the focusing 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 plate to 12 x 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 focusing 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 focusing, when it is placed in the carrier of the easel, it being retained in position with the spring S, Fig. 2. Focusing 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 black-lead.

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 curling 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 of curling inwards. The easiest way of exposing it is to procure two pieces of patent plate glass of the same thickness as the focusing 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, us 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 color 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.

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 whetted, 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 vigor 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 overexposed. 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 color 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 ounces.

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 color, 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 colors 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 colored prints are desired, an enlarged negative should be made and prints made there-from 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 colored transparencies so produced generally have a finer grain than those developed to a black or colder color, but unless the colors 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 x 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 vigor 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.