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

Page scan 000426 from Journal of the Society of Motion Picture Engineers

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 #:
000426
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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Nov. 1947 INTERMITTENT MECHANISMS 413 squared. This would permit the time for the first half of the pull-down to be reduced to 0.0026 sec 2 X 0.0748/2 10,000 X 12 in. .,/2 = °j°|-6 X 360 = 22'. The total pull-down angle would take place in 22 + 30 degrees = 52 degrees. The film travel, velocity, and acceleration curves would be as shown in Fig. 5 A. The forces on the film caused by its acceleration 111 22 17 c " 20,000 flf'4 -i «i 1— Lil 22 17 PULL DOWN (DEGREES) PULL DOWN (DFGREFS) A B FIG. 6. A, Travel, velocity, and acceleration of the film. B, Pull on the film caused by acceleration and film-trap drag. and the film-trap drag and the net force on the film are shown in Fig. 5B. It can be seen that the net force on the film is still no higher than one pound, the maximum pull on the film with the Geneva. 3. Rapid Deceleration of the Film. — A third possible way to reduce the pull-down time is to increase the deceleration of the film. During the last half of the pull-down, the forces on the film and the film-trap drag act in opposite directions so that if they are of equal magnitude the net force on the film is zero. If the deceleration of the film were increased from 5000 feet per second to 20,000 feet per second squared,