Beginning with the successful result of the theory that like development produces like results in the making of negatives, a theory upon which the writer has worked for some years and which has been put into practice by the tank developing machines, there are many things which are new to the photographer who still adheres to the old methods. It is useless to enlarge upon the uniformity of tank development except to say that special attention to each individual negative is usually labor wasted.
The man who wants the same class of negatives every time, has only to get the right developer, one to suit his plate or film, and then find the time of development for either, as the case may be, and save his time for other things while the developer is producing better results than if the negatives were being handled and watched.
There is, however, a long step beyond all of this. The photographer, amateur or professional, may obtain any effect that he may desire from pactically any one kind of photographic surface by thoroughly grasping the higher principles of exposure and development. This may seem to apply a contradiction to the former theory; on the contrary, by true development each operator obtains or may obtain just what suits his particular purpose and each will obtain individual results by his individuality of method as manifested in exposure, strength of developer and duration of development. This then brings us to the newer theory concerning which I am now writing.
In negative making let us observe first, what different effects would be wanted by different workers or by one photographer for different purposes. For instance, by A, a very thin negative full of detail for "soft," "low-tone" printing. By B, a negative giving strong effects and printing great contrasts in lights and shadows. By C, and by the great majority, a negative with good detail and with sufficient variety as to light and shadows. By D, a negative in three tones, light, dark and middle, with elimination of detail. We will say that A works for low tones for exhibition purposes and is strictly non-commercial. B is an amateur whose ideas of beauty in photography is the strength of the negative and the contrast in the print. C is a commercial photographer or an all-round amateur who does not reach after impressionism. D is an exhibition photographer, an impressionist at the other end of the scale from A and may be A himself working on totally different lines as if frequently shown in a collection of one man's work producing both "low-tones" and "poster" effects.
Many readers will say that but one result can be obtained with one particular plate and one paticular developer. The man who so believes may want to read this article; the man who can successfully produce the four effects from one plate and one developer may not. The former will probably say that for four kinds of results he must use four kinds of plates and four kinds of developers. He shows his advancement by being able to obtain these varied results by any means whatever; but he will show still greater advancement by being able to obtain all with a single set of tools instead of four. The "easy" way to get the four effects is thus: For A's negatives, a fast plate usually, instantaneous orthochromatic, over-exposure and weak developer, such as dilute metol. For B's negatives, a slow plate, just sufficiently exposed, and strongly developed. For C's negatives, a fast or medium fast plate with full, not over, exposure and medium development with strong metol-hydroquinone or pyro. For D's negatives, a slow plate decidedly underexposed and greatly over-developed, such as with hydroquinone. It will be something, at least, for many of our readers to know how these very different results may be obtained, even if, as I say, by different sets of tools.
Now to work on the practice of our advanced theory; we have several kinds of plates giving, as is supposed, as many different effects in negative making. They are generally the 1st, extra rapid; 2nd, extra rapid orthochromatic; 3rd, medium fast; 4th, the slow; 5th. the very slow, and, sth, the double-coated fast plate. Illustrations of these six general classes of dry plates are:
1st. Cramer's Crown, Seed's 27, etc.
2nd. Cramer's Instantaneous Isochromatic, Seed's
Rapid Orthochromatic. 3rd. Cramer's Anchor, Seed's 23. 4th. Cramer's Contrast. 5th. Seed's Process. 6th. Seeed's Non-Halation and Standard Orthonon.
Can the theory be made to apply successfully to these six classes of plates? The relative exposure required to produce the usual average results with each are as follows: Nos. 1 and 2, one; No. 3, three; No. 4, six; No. 5, ten and No. 6, one and one-half. After learning the average exposure of each of these varieties we can proceed to work out our theory. The non-halation plates are placed last in the list for the reason that with strong development they give even greater contrasts than classes 4 and 5.
Let us suppose the No. 1 class as being the only kind of dry plates that the worker has on hand and the stock solution of metol-hydroquinone is the one developer. The formula is as follows:
Water, nearly hot ................. 4 ounces.
Metol -----........................ 1/2 ounce.
Sulphite, dry ...................... 4 ounces.
Hydroquinone ..................... 1/2 ounce.
Carbonate, dry .................... 6 ounces.
For ordinary use dilute with equal quantity of water. To produce A's effects: over-expose the plate, make developer one-fifth average (with stock solution, one part to ten of water), and give three or four times, instead of ten to twenty times, period of development with usual solution. Use no bromide. To produce B's effects: expose barely enough for shadows and use normal developer, full development. Use slight excess of bromide. To produce C's effects: give correct exposure for shadows and normal developer and development, normal use of bromide. Further modifications may be made in the use of intensifiers and reducers; ferricyanide-hypo intensified increasing while the persulphate-ammonia diminishes contrasts and any inten-sifier increasing contrasts. The whole theory as to development stands largely upon the axiom that strong development exaggerates contrasts and that weak development diminishes it.