PhotoHistory

From: THE BARNET BOOK OF PHOTOGRAPHY

How to make Enlargements (part 1 of 2)

By John A. Hodges, 1898

Enlargements may be made by daylight, or by artificial light, and there are two methods of producing them, namely, by enlarging direct from the negative on to a sheet of bromide paper; or by first making a small transparency, and from that producing an enlarged negative upon a slow dry plate. The first is the method usually adopted by amateurs, probably because the necessary operations are fewer, and perhaps more simple. The second plan, however, possesses the advantage that the prints may be made by any process, be it carbon, platinum, or silver, and thus a great variety of effect obtained.

The first point however that the reader must decide is whether he will work by artificial light or by daylight. Each may be said to possess certain advantages, and with many the question resolves itself into one of personal convenience. Artificial light is, or should be, fairly constant in intensity, and if adopted there will probably be less waste of material through miscalculation of exposure. But if the source of light employed be other than a mixed jet, or the arc-light, if in fact it be of low intensity, negatives of a somewhat delicate type will be required in order to produce enlargements of the highest excellence. If the negatives are dense and strong, illuminants of low intensity, like oil or gas, do not possess sufficient penetration to duly register the denser portions of the negative, and the enlargements so made are apt to be deficient in half-tone, and hard.

With well-graded negatives of suitable quality, however, most excellent enlargements may be produced by artificial light. When artificial light is used work may be carried on at any time of day or night, in winter or summer. Those who adopt the daylight plan will, of course, be subjected to greater restrictions, at any rate, during the winter months, but amateurs who take a real interest in the work will do well to adopt the writer’s plan, and provide themselves with apparatus for each method of working.

ENLARGING BY DAYLIGHT.

There are two ways of enlarging by daylight. The first involves the exclusion of all actinic light from a room except that which passes through the negative. The alternative method of working is to employ an ordinary enlarging camera, such as are made by Middlemiss, or Lancaster. It is desirable, but not necessary, if the first plan be adopted, to secure the exclusive use of a room. One with a northerly aspect should be chosen, for if sunlight falls upon the window shadows will at some period of the day fall upon the negative, and produce unevenly lighted enlargements.

An upper room will be most suitable, and, if the light be a northern one, and there are no trees, or buildings to obstruct the view, a reflector may be dispensed with. If external objects intervene, however, one must be employed. It should be fixed outside the window-sill, at an angle of 45 degrees, and should be capable of adjustment. Let it be the full width of the, window and securely fixed for obvious reasons. A plate-glass mirror is effective, but expensive. A large drawing board painted dead white also answers well, but should not be left outside exposed to the weather.

Provision for excluding the light from the room is best secured by making a wooden frame large enough to fit closely against the window frame. Upon this a piece of stout calico should be tightly strained and secured with tacks. It should then be sized, and when dry will be as tight as a drum; it must then be covered with two thicknesses of stout brown paper pasted on. The frame is shown complete in Figure 1. Now at AA and BB screw two strips of wood, the distance apart must be regulated by the size of the negatives to be enlarged. The ordinary camera is intended to be used as the enlarging camera, and the distance from C to C should be just equal to the size of the back portion of the camera. On the lower rail BB screw a piece of 9 inch board to form a shelf or support D for the enlarging camera. Make a frame E of 1/2 inch wood 1 inch deep, the same size as the back of the camera, and screw to the shelf and top rail AA.

Now carefully cut away the brown paper and calico from the inside of this frame, at the part marked H and paste strips of brown paper round it so as to prevent any light passing except through the opening H. A strip of felt should be tacked all round the large frame to prevent any light from creeping in between it and the window frame. A couple of turn buttons will keep it in position. A firm table should be placed against the window close up to the wall to form a support for the enlarging easel. Now a little care must be taken in fitting up this portion of the apparatus, and it is better to have something more exact than the propped-up drawing board or printing frame, which is sometimes recommended. Get a carpenter to run out two V shaped rails as shown in Figure 2 at CC. They should be about the length of the table, and screwed down upon it. Procure a cheap drawing board about 15 X 12, and to the under side affix two pieces of wood with V shaped grooves corresponding in angle to the rails. This forms the base of the easel AA. Make a frame 22 x 20, or rather larger than the biggest enlargement that it is desired to produce. It should be constructed of 1/2 inch wood, and be 2 inches deep. It is shown in Figure 2 at 1 DDDD. Now make, or get made, a set of carriers EE, the largest of which should just fit into the frame. Narrow fillets of wood screwed each side will afford a rise and fall adjustment, and a thumb screw at G will fix the carrier in any desired position. To obtain the cross-movement screw the frame DDDD to a piece of inch board 5 inches wide HH. Place this exactly in the center of the base board, and screw fillets II of 1 inch wood to each side. This will afford a cross motion, and a thumb screw at J will fix the carrier frame when the necessary adjustment has been made.

In setting up an enlarging apparatus, whether it be for day or artificial light, it is absolutely essential to preserve the parallelism of its various parts, otherwise it will be impossible to produce sharp or evenly defined enlargements, and for this reason I have described somewhat fully the construction of a suitable easel. I may add that it will serve equally well for either daylight or artificial illumination, and I strongly advise the reader to construct, or have constructed, an easel on the lines I have laid down. With it either direct enlargements on paper can be produced, or plates may be used and enlarged negatives made. The easiest way of holding the paper during exposure is to procure two sheets of clear glass, patent plate is most suitable, sandwich the bromide paper between them, and secure with two strong bands of elastic. The complete apparatus in position for working is shown at Figure 3.

The second method of enlarging by daylight is by employing an ordinary enlarging camera. The same conditions as to lighting, etc., should be sought for, and the most convenient way of working will be to tilt the camera at such an angle as that the negative receives unobstructed illumination from the sky. A reflector in this case will not be necessary, but a piece of very finely ground glass should be placed about an inch in front of the negative in order to soften and diffuse the light. This method of working is shown in Figure 4.

ENLARGING BY ARTIFICIAL LIGHT.

Before describing the actual process of making an enlargement it will be well to deal with the alternative method of working, namely, by artificial light, as the manipulations of the sensitive material used are the same in either case. Practically the most satisfactory way of working by the latter method is to use an enlarging lantern properly fitted with a condenser. The general principles of such an apparatus are identical with those which obtain in an ordinary optical lantern. Methods which dispense with the use of a condenser are more or less unsatisfactory, and should be avoided. In the space at the disposal of the writer it is not possible to give directions for the construction of an enlarging lantern, but those who may desire to make their own, will find full instructions and working drawings in “Practical Enlarging.”

Enlarging lanterns of excellent quality are obtainable commercially, but for the guidance of the uninitiated it may be useful to refer a little in detail to one or two important points with regard to their construction. The condenser will first claim attention. The ordinary pattern consists of two plano-convex lenses mounted as shown in section at Fig. 5. This answers fairly well with the smaller sizes, but when the diameter of the condenser is large, a good deal of light may be lost. The interposition of a small meniscus or planoconvex lens, in the manner first suggested by the late J. Traill Taylor, and shown in Fig. 6, will be found a great improvement. Its proper position will be at the point where the divergent cone of rays proceeding from it just covers the large condenser. In our own practice we always place a diffusing screen of very finely ground-glass in front of the condenser at EE. The diameter of the condenser is governed by the size of the negatives to be enlarged, it must be of sufficient size to include the longer sides of the plate within its circumference without cutting the corners. If it is much larger than this, an unnecessary loss of light will occur, because only that which passes through the negative can be utilized.

The smaller and more intense the light, the nearer we approach to the ideal projection illuminant, and the better will be the definition of our enlargements. The arc-light most nearly fulfills the desired conditions, and if it be available it should certainly be employed. Next in point of utility comes the lime-light, preferably in the form of the mixed jet, and those who understand its manipulation are recommended to adopt it, but the majority of amateurs will probably find it more convenient to use either incandescent gaslight or an oil-lamp. Parallel wick-lamps should be avoided on account of the unequal illumination they produce, and if oil must be used a good circular wick burner will be found more suitable. Where house gas is available the incandescent gaslight is however much to be preferred. The light is perhaps not so powerful as that given by a really good parallel wick-lamp, but it is far more actinic and penetrating. The writer has used this light with great satisfaction, and therefore has no hesitation in recommending it. Some workers have been troubled by the appearance of an image of the mantle on the screen, but this can usually be got rid of by a suitable adjustment of the lenses and the light, and in any case by the interposition of a piece of ground glass between condenser and negative.