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

witness the presentation by Donald J. Bell of a paper on "Motion Picture Film Perforation" at the meeting of October 2-3 in 1916, the second formal meeting of the Society. Bell's demand for standardization started a continuing activity, through first a "Committee on Cameras and Perforations" in 1916, then a "Committee on Film Perforations" in 1921, which continued as a subcommittee of the Committee on Standards from 1924 to 1948. In line with the philosophy of simplification previously expressed, the long-standing importance of film dimensions was once more recognized, and the former subcommittee was made a full-fledged Engineering Committee in 1948. Dr. Emmett Carver of Eastman Kodak has been the very competent Chairman of this group since its formation, the members representing the film manufacturing companies and those most concerned with the handling of film through apparatus in which dimensional tolerances are critical. The biggest problems facing this Committee at present are those relating to the introduction of the new safetytype film bases. Film is ordinarily slit to dimension and perforated at the time of manufacture. After an indeterminate period of time, involving perhaps prolonged storage under various humidities and temperatures, and chemical processing, this film must pass smoothly and with great accuracy of positioning through a camera, printer, projector or perhaps some other sort of specialized film-handling equipment. The critical dimensions of these equipments have been chosen by long experience to match the characteristics of the old-style film base. Now, with new bases with different dimensional changes being introduced, the shoe is on the other foot: the film manufacturer must alter his initial slitting and perforating dimensions so that the dimensions in critical usage will be the same as before. American Standards for film dimensions pres ently "apply to the material immediately after cutting and perforating": the later dimensions at the time of film passage through an apparatus of some sort are of course known to be most important, but to date no one has been able to visualize a suitable procedure for extrapolating these back to the time at which the slitting and perforating is done. Another problem of this Committee has been concerned with the possible choice of a single preferred shape for the sprocket perforation of 35mm positive and negative film. A proposal for this5 has been forwarded to the Committee on Standards with the recommendation that it be made an American Standard. Finally, a recent policy decision in the field of film dimensioning is worthy of notice. Not all film is slit at the time of manufacture. 16mm and 8mm film stock is sometimes provided doublewidth, to facilitate processing, with final slitting-to-width done after processing. For one reason or another, a good deal of the film made in this way has not been slit with the accuracy in width required to meet the American Standard dimensional tolerances, and poor sound reproduction, excessive picture weave and even film jamming in projection has resulted. The Committee considered the desirability of preparing a second and less rigid dimensional standard for 16mm film, to apply only to film slit from 35mm or 32mm stock after processing. This idea was soon rejected, however, on the basis that the present 16mm dimensional specification is required for interchangeable performance in all equipments, without reference to the manner in which the film is made. Thus there is no logical reason to let down the bars solely for the purpose of permitting all laboratoryslit product to qualify under a Standard of some sort. Since American Standards are not compulsory, a considerable market can and often is developed in nonstandard merchandise of all sorts. 164 September 1952 Journal of the SMPTE Vol. 59