International photographer (Jan-Dec 1934)

Twenty-eight The INTERNATIONAL PHOTOGRAPHER July, 1934 NEGATIVE OR REVERSAL FILM FOR THE AMATEUR (Continued from Pa ye 24) therefore, more or less neutralized, and the scenes which were purposely under-exposed and overcorrected by means of a filter, such as the F-29, are usually printed as daylight scenes. In the negative-positive system, however, where the printing light is controllable according to the density desired, excellent night filter effects can be obtained. With negative, also, it is possible to expose for any portion of the picture, whether it be light or dark, while in reversal processing the photoelectric cell exposes for over-all density, and if there is a great deal of light in the picture, such as sky or snow, darker objects will be considerably underexposed. When using reversal film it is necessary to keep in mind that excessive contrasts are exaggerated on the film, and should, therefore, be avoided. For best results, the object which it is desired to have correctly exposed should have about the same illumination as the majority of the rest of the scene. With negative this is not so important because the desired object, if reasonably correctly exposed, can be given correct exposure in printing, regardless of the light intensity of its surroundings. Inherent characteristics, such as speed and color rendition, of negative and reversal film (assuming, of course, that both films are of the same general type, i.e., panchromatic or super-panchromatic), aside from the differences brought about in the processing, are not sufficiently different to concern the amateur. However, the two firms which manufacture the majority of 16mm. negative in this country — Dupont and Agfa — are undoubtedly able to supply data with which their negative film characteristics can be compared to those of reversal film. Where only one print is needed, as is usually the case with the amateur, reversal film is the cheapest and surest to use, but the amateur should not overlook the fact that it is his only record, and once it is damaged in screening it cannot be replaced. It is readily possible, of course, to make duplicate prints of reversal film by first making a negative from the original, but this process is so much more expensive and somewhat less satisfactory than using negative from the start that the amateur would be wise to make all valuable pictures directly on negative. The additional original expense will repay itself in the long run. Pictures of the children as they grow up should, by all means, be made on negative. In later years they will be invaluable, and, if destroyed, cannot be replaced. Reversal film, after a certain amount of use, becomes dirty, brittle, and so badly scratched that it is practically impossible to make a satisfactory dupe from it. Negative film, however, may be stored away in humidor cans to keep it pliable and used to make good, cheap prints for many years after the original print has worn out. It is worth the slightly added expense, now that fine quality and fine grain is commercially obtainable in negative film, to have good movies of tbe children after they have grown up. The same applies to pictures of important events or of scenes taken in distant lands which cannot readily be revisited, for frequently their value increases with their age. It is unfortunate that reversal film and prints made from negative cannot be used together, for then it would be possible to intercut between the two in the same reel, so that the very valuable scenes could be made on negative and the less valuable ones on reversal, if two cameras are available. This is not possible, partly because the difference in the quality of the two films might be objectionable, but chiefly because reversal film must be projected with the emulsion toward the lens (since it is the same film which was exposed in the camera with the emulsion side toward the lens), while in projecting positive prints the emulsion must be away from the lens. The thickness of the celluloid base is sufficient to throw one out of focus when the lens is focused for the other. To save the expense of making titles on reversal film the amateur may use positive film by making the titles with black letters on a white background and developing the positive as such (not reversing it), thus giving white letters on a black background, which can be projected with the emulsion toward the lens, as is the reversal film. The original cost of positive film is greatly less than that of reversal film, and the developing cost in a commercial laboratory is very reasonable (about one cent per foot), keeping the total cost far below that for reversal film. If developed at home — and this can be easily done in short lengths — the total cost of the titles is practically that of the raw positive. Positive film for titles has the added advantage of being more contrasty than reversal or negative film, thus producing clearer titles, especially when developed in positive developer. It must be remembered, of course, that positive film is much slower than that sold for regular camera use, and the exposure must be increased accordingly. A little experimenting will soon tell the amateur what exposure to use. Where the lighting conditions are particularly favorable out of doors on a bright sunny day, positive film can also be used to photograph many scenes, but it usually requires a wide open lens (f:3.5), cannot be used with filters of any kind, and gives an orthochromatic rendering with somewhat contrasty results. It does, however, by virtue of its slow speed (the greater the speed of an emulsion the larger the grains of silver bromide), give very fine grain results. It can also be reversed to save the expense of having a print made, but that must be done at home, as commercial laboratories usually use solutions and methods which are not suitable for positive film reversing. To the advanced amateur who is able to do his own developing and printing the negative-positive system offers great possibilities. He will find the raw negative considerably cheaper than reversal film, and with his own developing and printing the cost should still be less. He need, of course, print only the good scenes of the negative, thus further cutting down expenses. The amateur who does not do his own laboratory work may, in the long run, find negative cheaper for the same reason — if he knows he will have a lot of bad or unnecessary scenes he can readily cut them out of the negative before having it printed. With his own laboratory the ingenious amateur can produce many special effects through special printing possible only with the negative-positive system. This does not necessarily require expensive or elaborate printing equipment, for a printer which will prove quite satisfactory and will do many things most 16mm. printers on the market today cannot do, can be built fairly cheaply and easily. In my own case I have built a printer with which I can obtain many effects obtained in 35mm. printing, such as fades, dissolves, wipe-offs, and double exposures. The entire printer was made with five and ten cent store tools, using such odds and ends as anyone might have lying around or be able to get easily, the central unit being an old Q. R. S. DeVry camera. I have also built my own processing racks and tanks at little expense. The mechanically inclined amateur should have little trouble in building his own laboratory equipment, especially with the help of the literature available on the subject. Even with crude laboratory equipment it is possible to get some excellent and professional looking results. In handling negative film great care must be taken that it is not scratched or soiled, as this naturally shows up in the print. In the commercial laboratories the film is thoroughly cleaned before printing so that all dust and dirt is removed, but scratches are permanent. Negative film base Please mention The International Photographer when corresponding with advertisers.