Projection engineering (Jan 1932-Mar 1933)

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Page 8 PROJECTION ENGINEERING Causes of film mutilation By Sylvan Harris ACCORDING to various estimates, the cost which the motion picture industry is called upon to bear because of the amount of film that is mutilated in projection, due to the maladjustment of projector parts, wearing of the parts, and the use of incorrect tensions and tolerances, runs into hundreds of thousands of dollars. Anything that can be done to alleviate this serious condition will, of course, be greatly appreciated by the entire industry, especially during the difficult period through which it is now passing. Realizing the seriousness of the situation, the Projection Practice Committee of the Society of Motion Picture Engineers has undertaken an intensive study of the factors that contribute to the mutilation of prints, with the view of considering what means may be taken to correct the difficulty. The causes of film mutilation are many, and for this reason it is difficult to judge what cause is the most important. At any rate, it is clear that they may easily be divided into two categories which, together, will include all the causes. These are: (a) the condition of the film, and (b) the condition of the projector. It is unnecessary to introduce a third category, relating to the conditions under which the film and the equipment are handled or operated, respectively, as these may be understood to be included in the categories (a), and (b). At the present time, film may be received at the theatres either "processed" or "unprocessed," according to the usual acceptation of the terms, which refer to the buffing, waxing, or oiling of the prints. In the case of "unprocessed," or improperly treated film, the photographic emulsion is likely to accumulate at the projector gate and at the sound gate, giving rise to severe strains on the film at the sprocket holes, due to the increase of tension at the gates. On this account the film may become dam aged and may be displaced somewhat from the focal plane of the lens structure, impairing both' the definition of the picture and the quality of the reproduced sound. When oil or wax is used for "processing" the film, similar difficulties may arise due to the spreading of the wax or oil under the action of the heat radiated by the projector lamp, and the consequent accumulation of dirt in various parts of the projector. The Projection Practice Committee considers the solution of the "processing" problem, the determination of the best method of "processing," to be of utmost importance to the industry, and extends its invitation to producers and exchanges to cooperate in devising and standardizing such a method of treating positive prints. The tentative recommendation is made that a process be devised for hardening or fixing the emulsion so as to prevent "shedding" and consequent accumulation at various points in the machine, rather than to prevent this from happening by applying oil or wax. A summary of the subject reveals the following facts : 1. It has been shown quite definitely PROJECTIONISTS and others who are interested in the problems of motion picture -engineering are invited to write to the Editor of Projection Engineering, or to the editorial office of the Society of Motion Picture Engineers, 33 West 42nd Street, New York, N. Y., for information which they may need in solving their problems, or for information regarding membership in the Society or subscription to the Journal. that more trouble is experienced at the projector and sound gates with first-run film than with film that has been run a number of times. 2. New film, in passing through friction devices, causes an accumulation of deposits in the device which produce the effects described. 3. The accumulation of these deposits not only influences the quality of the projected picture and the reproduced sound, but results in scratching of the film as well. 4. In searching for a method of alleviating these difficulties, it should be The Projection Practice Committee of the Society of Motion Picture Engineers inaugurates program of inquiry into the causes of film mutilation SYLVAN HARRIS Editor-Manager, S. M. P. E. borne in mind that the film, when passing through the sound gate, is at a rather high temperature, due to its exposure to the radiation of the projector lamp, as it passes the picture gate. Any method which may be devised for treating the film should be such that the film remains in suitable condition for use at the high temperatures thus encountered. In connection with the fourth item, it has been claimed that the heating of the film by the high-intensity arcs causes the film to become dry and brittle, and to buckle or break. This effect is said also to occur in hot and dry weather. Further, as the film is wound upon the lower magazine, it is quite warm ; upon cooling, it contracts, and it has been said that this, too, is one of the causes of the damage done to film. The suggestion has several times been made that the film be cooled by a blast of air before it enters the lower magazine. No less important than the effects of heating the film and the treatment giver, it prior to projection, is the conditior, of the projection machine, on the amount of film that is damaged in use And, in turn, the condition of the ma chine is dependent upon the tensions applied, the clearances allowed, and the amount of wearing experienced at two dozen or more points of the mechanism. Accordingly, the Projection Practice Committee set about determining the correct tensions and clearances to be maintained at the various points in the projector, and to determine, wherever possible, the extent to which wearing of the various moving parts may be tolerated before replacements or repairs are necessary. Starting at the upper magazine spindle, and following the path of travel of (Concluded on page 23)