A-B-C of motion pictures

by Robert E. Welsh

THE FACTORY

The average amateur photographer, who has made a practice of developing and printing his own photographs, will find little of interest in a description of the stages through which the film passes in a motion-picture factory. It is essentially the same process that he follows, though, naturally, on a much larger scale and making use of all the mechanical appliances possible. The variations in the chemical formulas used are those which the studious amateur’s own judgment would dictate to him were he working under conditions similar to those of the motion-picture photographer.

His day’s work completed, the camera-man takes his negative film, which is contained in the take-up box of the camera to protect it from the light, to the factory. The film taken from the camera now faces the following steps: the development, washing, and, finally, fixing, thus producing a “negative” from which the “positive” prints used for exhibition purposes are to be made. The development of the negative takes place, of course, in a “dark room,” that is, dark in the photographic sense, the sole illumination being that of lamps providing a pure red light. The negative strips are wound spirally about pins on a rectangular rack, thus making it possible to wet the entire surface of the film simultaneously and equally when the rack is submerged in the developing solution.

Metal and hydroquinine are the chemical agents most active in the developing solution most commonly used, soda sulphite, soda carbonate, potassium, metabisulphite, and water completing the formula. But even for standard work there are varieties of developing-baths, while to handle film taken under out-of-the-ordinary conditions still further changes are made. It is in his ability to meet varying circumstances that the factory executive shows his mettle. Test developments may be made on a few inches of film to indicate the exact process to be followed. The washing of the film, and its submersion in the “fixing”-bath are the next items, also familiar to the ordinary photographer. The “fixing”—that is, submersion in a solution of sodium hyposulphite—renders the negative immune to the light, after which it is once more washed, this time to remove the “hypo” of the fixing-bath. The negative may now be treated with a diluted solution of glycerine, which renders it soft and pliable, for there is much wear in store for this negative.

We have seen previously how each scene taken during the day was numbered to aid the producer in assembling the picture in the proper order. The negative strips are now assembled in a complete strip and viewed by the executives of the company before the first positive print is made. This initial inspection will, like as not, show that some of the scenes must be retaken, either because of poor photography or for some other reason not noticed by the director at the time the original scene was taken. “Retakes” are, naturally, not popular with the men who pay the bills, though they are often due to natural causes beyond the power of the director or camera-man to forestall. As picture producers always take a good deal more film than will be used in the subject shown later in the theaters, this viewing of the negative will also aid in bringing the picture down to the required size and in deciding on the printed inserts needed, though it is also probable that a good deal of cutting, reassembling, titling, and so on, will be done after the first positive print is made.

The negative approved, we are now ready to print the positives. On the negative, as the amateur photographer will know, the light conditions were reversed from the normal. That is, the portions of the film which we would expect to appear white, such as a snow-covered walk, were black, while the dark portions, a railroad train, for example, appeared white. This is the principle explaining the method of printing positives. The negative is superimposed on the positive film stock and light allowed to stream through. Naturally the image on the negative obstructs light in proportion to its density. Our snow-bank, let us say, being black on the negative, will allow no light to pass through and that portion of the positive stock under it will not be exposed. The near-by train, appearing white on the negative, offers no obstruction to the light, and here the positive is strongly exposed. When the positive is later developed it takes on a deposit of silver in equal proportion to the strength of the exposure, the snow-bank taking little, while a heavy deposit of silver clings to that part of the film showing the railroad train, which received so much exposure to the light. Thus the positive print brings the light conditions back to normal again, the train appears dark, the snow white, and the other objects in the scene shaded in ratio to the amount of light they allowed to penetrate through the negative to the positive stock.

In practice positive printing is done by a machine using for its essential principles the shutter and feeding devices that we have seen in the motion-picture camera. Negative and positive stock are perforated alike, and when superimposed the perforations fall in alignment. The film-feeding device of the printer engages in these perforations just as we saw it do in the camera, only in this case it is moving the negative and positive film along simultaneously. What would be the lens in the camera is here the place where the light is allowed to pass through. Once more the shutter serves its purpose of shutting off the light while the required length of film for one small picture is shifted into place. As in the camera, care is taken that the light strikes no portion of the film but the three-quarter-inch strip that is being exposed. The action of a printer is practically automatic, but the human touch is evident in determining the brilliancy of the light, its distance from the film, and the speed at which the printer will be run, all points determined by the condition of the negative.

(Selig)

The developing of positive film is a process much similar to that we have just described for the negative film. The chemicals used in the formulas are much the same, though the proportions vary. As positive film is less sensitive to light than negative, the developing need not be done in a dark room, though even here daylight, or the “yellow” light of the common electric bulb, is not permissible. To the eye positive and negative film appear much alike, and, in truth, they differ only slightly to render them more adaptable to their different uses. The drying of both positive and negative film, following the various operations, is accomplished by means of large drums, on which hundreds of feet may be wound.