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

Page scan 000425 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 #:
000425
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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412 HAYEK Vol 49, No. 5 The film travel, velocity, and acceleration curves are shown in Fig. 4A. The forces on the film due to its acceleration and film-trap drag and the resulting net force on the film are shown in Fig. 4B. It can be seen that although the pull-down time is reduced, the net pull on the film is still the same as that of the Geneva. 2. Variable Film-Trap Drag. — Another possible way to reduce the pull-down angle is to vary the film-trap drag. The only purpose of the film-trap drag is to decelerate the film during the last half of PULL DOWN (DEGREESI PULL DOWN (DEGREES A B FIG. 5. A, Travel, velocity, and acceleration of the film. B, Pull on the film caused by acceleration and film -trap drag. • -. v the pull-down. It is not needed during the first half of the pull-down when all it does is hinder the acceleration of the film. It would, therefore; be desirable to have film-trap drag only during the last half of the pull-down. This might be accomplished by means of an electromagnet which would release the pressure of the film gate during the first half of the pull-down. If this could be done, then during the first half of the pull-down, the pull on the film would be only that due to its acceleration alone (J/2 pound). Since we are allowing a maximum pull on the film of one pound, the pull on the film due to acceleration alone could be doubled and its acceleration increased from 5000 to 10,000 feet per second