International photographer (Jan-Dec 1934)

fwenty-four T h INTERNATIONAL PHOTOGRAPHER Juh, 1934 NEGATIVE OR REVERSAL FILM FOR THE AMATEUR? 16 mm. By Walter Bluemel UN view of the fact that all professional motion pictures are made by the negative-positive system, it seems rather strange at first that in amateur lbmm. photography the entirely different methods of reversal film should be used. But there are many reasons for this departure. First and foremost is the matter of cost. In the reversal process the negative exposed in the camera is reversed into a positive, thus doing a\va\ with the expense of an additional film and of printing and processing it. With improved processing machines now used for reversal film, the developing and reversing is "For years our work has been the production of photographic effects for the major motion pictures studios of Hollywood and in almost every instance we were compelled to utilize double and triple exposures employing both original and duplicate negatives. It is obvious, therefore, that we should be keenly alive to any method that would reduce grain. "Dr. Sease, of Dupont, was the first to impress upon us the possibility of Paraphenylene Diamine as a base from which to carry on our research work. But aside from the fact that as a chemical it is much more expensive, it seemed to indicate a requirement of greater negative exposure. Limitations of this sort are vital. "There were two other factors against it, one the possibility of poisoning if handled without rubber gloves, as well as bad staining of the hands, and, secondly, the practically one operation, and that fully automatic, while excessively long developing time. in the negative-positive system there must necessarily be three distinct processes — developing of the negative ; printing of the negative on positive stock ; and developing of the positive. All this raises the cost of the negative-positive system for the amateur, though in professional pictures this additional cost is negligible, especially in view of the fact that any number of prints can be made from a negative, while in reversal film there is only one print. Another important drawback in the negative-positive system for the amateur, but one which is rapidly being overcome, is that it gives more grainy results than reversal film. This does not mean that the reversal film has inherently finer grains of silver bromide. The difference is due to the processing, in which the silver bromide which has been exposed to light is changed to little grains of silver. Reversal film, when developed as a negative, under the same conditions as the negative film would be developed, is just as grainy as is negative film. All modern emulsions are originally of sufficiently fine grain to be entirely satisfactory, but in the developers used until recently the grains tend to clump together and produce larger, objectionable grains. In reversal processing, however, these coarse grains, which have been exposed by the cinematographer, are bleached out and the finer and slower speed grains in the emulsion remaining are exposed to light in the reversal laboratory and developed into a positive. Finer grain, without sacrifice of speed (as faster emulsions have larger grain), is thus obtained. The combination of these two advantages has been sufficient to establish the popularity of the reversal film over the negative. Recently, however, with the development of paraphenylene-diamine base developers, very fine grain results have been obtained in negative which compare most favorably with reversal film. Further improvement along this line is imminent. Negative film is gaining in popularity and may soon offer considerable competition to reversal film, if not actually surpass it. At present the more universal use of negative film is curbed by the lack of fine grain processing laboratories and the resulting higher charge for developing and printing. I know of only one 16mm. laboratory in the country which uses the paraphenylene diamine developer, regularly and has done sufficient research along the line of fine grain developing to obtain consistent results. That is the Dunning Process Company of Hollywood. To quote Mr. Carroll Dunning: "The problem in straight negative developing (not reversal) is to prevent clumping of grains and until recently all known developers seemed to have this fault. "But some six months of testing in our research department has brought us a formula along with other chemicals that make us consider the time well spent. For want of a better name we call it Dunning Grainless. "It produces a pseudo-physical developing, colloidal in character, in which the old bugbear of clumping seems to have disappeared. "We have not been able, of course, to eliminate the danger element in handling the baths except that our operators all wear rubber gloves. We still require about three times as long to develop. Unfortunately it is a characteristic of all developers that a shortening of the developing time increases grain clumping, so if we are to take advantage of the superior qualities of this new developer we must spend the time to get the best results. "'Grainless developing as now practiced in the Dunning Hollywood Laboratories does not compel the amateur to use any more exposure than he has been using with reversal film." Judging from my own personal experience, however, I would suggest a slight increase in exposure (perhaps one stop, where possible) to obtain the best result. On negative over-exposure is always more desirable than underexposure, as it can usually be corrected in printing, whereas on reversal film slight underexposure is permissible. Paraphenylene diamine developers produce thin negatives, even when properly exposed, but these give very excellent prints, with finer tone gradation than do reversal films. The prints are, generally speaking, not as contrast}-, but are nevertheless sufficiently snappy and very pleasing if properly exposed, processed, and printed. I do not believe, however, that one has quite as great a latitude of exposure as with reversal film. There is more detail in the shadows than on reversal film, and the one gradations are more like those perceived by the eye, that is, there is not as much contrast between them. It must be remembered, of course, that the best results can be obtained only with correct exposure. Negative film has another advantage over reversal film, and that is in its use with filters. It is impossible to obtain certain filter effects, such as night effects in daytime, with reversal film because of the automatic character of the processing machines for this film. These machines, after the original development has been completed and the silver grains bleached out, attempt, by means of a photo-electric cell, or "electric eye," to automatically correct the exposure of the reversed "print" so that it is always uniform. Scenes which have been over-exposed are printed darker and underexposed scenes lighter. Night filter effects are (Turn to Page 28) Please mention The International Photographer when corresponding with advertisers.