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 #:
000654
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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VARIABLE AREA SOUND FILMS 637 properly. The reason for this is the difference between the response of the eye to differences in intensity of light and the response of the photo-electric cell to similar differences. The current passed by the photo-cell is a linear function of the amount of light which falls on it. Obviously, then, the greatest response that can be obtained from any film is that corresponding to complete extinction of the light when the dark part of the wave is over the slit and 100 per cent transmission over the light half of the cycle. This output can be cut down in two ways: by the transmission of some light through the dark half of the track, and by the B c FIG. 1. Three variable area records. absorption of some light by the half which should be transparent. If we call the maximum possible output 100 per cent and subtract from this first the per cent of light actually transmitted by the dark half and then the per cent absorbed by the light half of the track we will have left the per cent output, in terms of photo-cell current, that will be obtained from the film. These relations are shown in the curves of Fig. 2. The upper curve shows the outputs which would be obtained from the indicated densities on the dark side of the track if there were no absorption on the clear side. The lower curve shows the amounts by which these values