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

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tive and positive films on sprocket-type printers. With low-shrink safety base, however, sufficient shrinkage did not occur. It was found desirable, therefore, to "pre-shrink" the film by perforating it at a slightly shorter pitch than that previously used. The pitch selected was 0.1866 in. This is approximately 0.2% less than standard pitch instead of 0.3% as required by theory. It is found in practice, however, that this pitch produces satisfactory prints even when no shrinkage at all has occurred and still allows a margin for any shrinkage that is likely to occur later. It also introduces a minimum change in the action of the film in the camera. Tests have shown that cameras can take film of this pitch quite as well as film of the standard pitch. The case of master positive and duplicating negative is not completely solved by this new standard. Each one of these is used in the printer on the outside of the arc when the image is printed on to it and on the inside of the arc when the image is printed from it. No single pitch, therefore, can take care of both of these cases. In actual practice it is generally found satisfactory to use standard pitch for the master positive, short pitch for the duplicating negative and to do all the printing on continuous printers. — E. K. Carver. 528 December 1952 Journal of the SMPTE VoL 59