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Three New Standards
THREE RECENTLY APPROVED American Standards appear on the following pages:
1. Cutting and Perforating Dimensions for 32-Mm on 35-Mm Motion Picture Negative Raw Stock, PH22.73-1951
2. Zero Point for Focusing Scales on 16-Mm and 8-Mm Motion Picture Cameras, PH22.74-1951 (Revision of American War Standard Z52.51-1946)
3. Mounting Threads and Flange Focal Distances for Lenses on 16-Mm and 8-Mm Motion Picture Cameras, PH22.76-1951 (Revision of American War Standard Z52.50-1946)
The first standard was developed by the Film Dimensions Committee and first published as a proposal in February 1949.
The reason for the existence of this type of film (35-mm film with 32-mm perforations) is that it can be processed on 35-mm sprocketless developing machines with consequent saving in equipment. This film is commonly used for sound recording and reduction negatives. The negative thus made is printed in the usual fashion. In general, this 32-mm on 35-mm film is not used for release purposes. However, the fact that people other than manufac
turers can perforate 35-mm film in this way has led to some concern. If 35-mm nitrate film were to be perforated with 32-mm perforations, it might later be slit to 16-mm size and be used in projection equipment. The standard, therefore, includes the proviso: "This film should not be made on nitrate base because if this material were slit to 16-mm it might be used on a projector with consequent danger of fire."
No proviso of this sort has been indicated in other standards because it is an unwritten law in film-manufacturing companies that no nitrate-base film should ever be slit to 8-, 16-, or 32-mm widths. The manufacturers do, however, slit both nitrate and acetate film to 35-mm dimensions. Other film users sometimes buy unperforated film and perforate it as they see fit. It was thought, therefore, that special attention should be called to the danger that might result if nitrate film were perforated to any dimensions that might make it usable on 16-mm projectors.
The other two standards resulted from the work of the 16-Mm and 8-Mm Committee in reviewing and revising two War Standards, Z52.50-1946 and Z52.511946. The revisions in both standards consisted chiefly in making them apply to 8-mm as well as 16-mm cameras.
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June 1951 Journal of the SMPTE Vol. 56