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Film Dimensions Committee Report
By E. K. CARVER, Committee Chairman
JL HE REPORT that follows is much longer than that which the Film Dimensions Committee ordinarily has given. One reason is that it leads up to a discussion of progress toward international standards, as information on this matter has not been widespread through the Society's ordinary channels of communication. Another reason for a lengthy report is that we wish to discuss a situation concerning 16mm film, a field wherein so many people are engaged that they seldom get together in the manner that happens with those who use 35mm film. Accordingly, the committee has sent out several circular letters and desires to make a relatively long public report in an effort to reach everyone that may be interested.
A questionnaire was sent out in March, 1952, to some thirty manufacturers of 16mm film equipment, and the results have been studied. It appears from the replies to the questionnaire that we have not sufficiently emphasized the fact that the proposed change in standard dimensions will not make the present film narrower in width than the film formerly used in cameras or other equipment.
You will remember that the standards are written to describe the film "immediately after cutting and perforating." Although it was very clear in the minds
Presented on October 8, 1952, at the Society's Convention at Washington, D.G., by Dr. E. K. Carver, Kodak Park, Eastman Kodak Co., Rochester 4, N.Y.
of those who wrote the early standards that these standards referred to widths at the time of slitting, nevertheless there has been the tendency among equipment manufacturers to interpret them to mean the maximum and minimum widths of film that would ever be encountered under any circumstances. The manufacturers of equipment soon learned by experience that film would often be found considerably narrower than the standards. This fact was properly interpreted to be due to the shrinkage of the film. Whenever equipment manufacturers found film to be wider than the standards, they assumed that the film was improperly slit. They did not fully realize that film swells at high humidity and that film, even though properly slit, might swell under high humidity conditions so that its width would be greater than standard.
One reason why this swelling effect was not better known was because of the rapidity of shrinkage which occurred with the old type of high-shrink film. As soon as the package was openecj (or even before this in case it was not adequately, hermetically sealed in a metal container) the film started to lose residual solvents and to shrink. This loss of solvents was more rapid at high humidities. Under most circumstances, therefore, the increase in width due to absorption of moisture from the air was more than counterbalanced by the decrease in width caused by loss of solvents to the air. For this reason it was rarely found in practice that film would be
November 1952 Journal of the SMPTE Vol.59
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