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

Record Details:

Title:
Journal of the Society of Motion Picture Engineers
Date:
1930-1949
Publisher:
New York, N.Y. : The Society
Volume:
Journal of the Society of Motion Picture Engineers
Leaf #:
000146
Language:
English
Collection:
Technical Journals
Format:
Periodicals
Contributor:
Prelinger Library
Sponsor:
MSN
Coordinator:
Media History Digital Library
Description:
The Journal of the Society of Motion Picture Engineers (SMPE)Êdocuments the technological progress of the film industry, highlighting technical developments in production and exhibition. Of special interest are articles about special effects, theater practices, lighting, and the introduction of the 16mm format. Initially titled "Transactions of the Journal of the Society of Motion Picture Engineers."Digitized by the Prelinger Library and the Library of Congress Motion Picture, Broadcasting and Recorded Sound Division.
Date Added:
July 19, 2022
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Aug., 1944 MODERN PROJECTOR DESIGN 137 the intermittent motion. Many people fail to grasp the fundamental reason for the employment of a Maltese cross in the projector, and one hears frequent suggestions that various types of claw motions would be quite suitable if they could be made sufficiently robust. Such suggestions fail to take account of the fact that no practicable type of claw motion will produce a picture shift of less than 90 degrees with reasonably good acceleration, and if the shift period is not less than 90 degrees, the shutter will have an efficiency Mi/lisecoads FIG. 4. Velocity and acceleration curves of standard Maltese cross movement (calculated). of less than 50 per cent (it is essential for the avoidance of flicker that both blades of the shutter should be of approximately equal angle). Actually, the shift period of a Maltese cross, geometric considerations notwithstanding, is appreciably less than 90 degrees, due to the slight slackness of the striker pin within the cross slots; most projector shutters actually have blades of less than 90 degrees.10 A still quicker shift period would of course permit of narrower shutter blades and greater light transmission; but it is only with a theoretical shift period of 90 degrees that tangential entry and leave of the striker pin in the slots becomes possible. The old Pathe" machine had a shift