Journal of the Society of Motion Picture Engineers (1930-1949)

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wider than the original slit width and, therefore, manufacturers of equipment began to consider that the standards represented the maximum that they would ever encounter. There was a tendency, therefore, to construct film gates and other equipment so that they would pass film with a width of 0.630 in. (16.0 mm) but of no greater width. They felt that any film which exceeded this width must be nonstandard film. During the past ten or fifteen years film manufacturers have found means to improve the shrinkage characteristics of film and can be expected to make further improvements. Severe conditions which might cause the older type of film to shrink about 1% would cause the newer type of film to shrink only 0.2 to 0.4%. The present film often reaches the camera with no shrinkage whatever. There is not much difference, however, between the amount of swell due to absorption of moisture that occurs with the newer type of film and that which formerly occurred with the older type of film. It thus has become much more common to find the newer type of film wider than standard. Since much of the equipment has been constructed so as not to accept film with a width appreciably greater than 0.630 in., complaints have arisen that the film was slit too wide. These complaints forced the film manufacturers to change the setting of their slitting knives from about the middle of the standard tolerances down to a point near the narrowest tolerances allowed. Accidental variations in slitting meant that some of the film was slit narrower than the allowed tolerances but no complaints were ever received for that reason. Complaints were still received, however, on film which appeared to be too wide at high humidities. The slitting knives were set still closer to the bottom tolerance. This practically eliminated complaints from film which was too wide but did not introduce any complaints or any difficulties from film which was too narrow. This was true even though a large fraction of the film fell below the "standard" width. An investigation was undertaken to find out what the widths have formerly been at the time the film was actually used. Statistical studies were made on many samples of film purchased on the open market and of film at the end of its useful life. Measurements were also made in 16mm film exchanges of the regular, professional distribution systems. The various measurements showed clearly that the newer type film even with a reduced slitting width typically would reach the customer with a greater width than old type film. However, the width was not great enough so that one could expect any more trouble at high humidities than have been previously encountered. The present attempt to change the standard for slitting 16mm film, therefore, is merely an attempt to recognize in a formal manner the changes which the film manufacturers have been forced to make in order to avoid complaints and to give the customer film as near the old width as possible. We call this an effort to maintain the "status quo," which is what the ultimate user often needs. The Film Dimensions Committee is anxious to make sure that all of the equipment manufacturers thoroughly understand this problem. If these manufacturers were to misinterpret the new standard and reduce the dimension of film gates, then we would be in serious trouble. Complaints of film jamming would increase. Pressure would be put on the manufacturers of film to reduce the width of their film. Competition would force some of them to do so, and then there would be pressure put on the standardizing bodies to reduce the standard width again to conform to the width actually in use. One change would follow another, leading to chaos. Three methods have been proposed to revise the standard to take care of the above problem. One of them was 424 November 1952 Journal of the SMPTE Vol. 59