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

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American Standard Scanning-Beam Uniformity Test Film for 16-Millimeter Motion Picture Sound Reproducers (Service Type) Rrf. V. S. Pat. Of. Z22.81-1950 'UDC 778.534.4 1. Scope and Purpose 1.1 This standard describes a film which may be used for determining the uniformity of scanning-beam illumination in 16-mm motion picture sound reproducers. The recorded sound track shall be suitable for use in the routine maintenance and servicing of the equipment. 2. Test Film 2.1 The film shall be a print from an original negative. It shall consist of a 1000-cycle, variable-area recording at full modulation of the 0.005-inch width and shall be approximately sinusoidal. The track shall move uniformly 0.067 inch from one edge of the scanned area to the other as shown in Fig. 1 . 0.072 in. — H «— Fig. 1 2.2 The position of the sound track relative to the ends of the light beam at any instant shall be shown by a diagram appearing in the picture area, the size and location of which is shown in American Standard Location and Size of Picture Aperture of 16-Millimeter Motion Picture Cameras, Z22.7-1950, or any subsequent revision thereof approved by the American Standards Association, Incorporated. 2.3 The scanned area shall comply with American Standard Sound Records and Scanning Area of 16-Mm Sound Motion Picture Prints, Z22.41-1946, and the film stock used shall be cut and perforated in accordance with American Standard Cutting and Perforating Dimensions for 16-Mm Sound Motion Picture Negative and Positive Raw Stock, Z22. 12-1 947, or any subsequent revisions thereof approved by the American Standards Association, Incorporated. 2.4 The length of this film shall be approximately 3]/2 feet. NOTE: A test film in accordance with this standard is available from the Motion Picture Research Council or the Society of Motion Picture and Television Engineers. Appendix (This Appendix is not a part of this American Standard.) Before using the above test film it is recommended that correct placement of the scanning beam be determined by means of buzztrack test film as specified in American Standard Specification for Buzz-Track Test Film for 16-Mm Motion Picture Sound Reproducers, 222.57-1947, or any subsequent revision thereof approved by the American Standards Association, Incorporated. The uniformity of scanning beam illumination may be measured by means of a db meter connected to the output of the sound projector amplifier. The illumination of the scanning beam should be adjusted according to the instructions furnished by the manufacturer and the variation of the output as registered on the db meter should be observed. The illumination is considered satisfactorily uniform when the output reading as measured by the meter is within — 1 Vz db across the entire scanning slit. Approved June 12, 1950, by the American Standards Association, Incorporated Sponsor: Society of Motion Picture and Television Engineers 'Universal Decimal classification November 1952 Journal of the SMPTE Vol.59 431