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 #:
000307
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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300 C. E. K. MEES [J. S. M. P. E. tionately increase the minimum intensity of sound, or ground-noise, and the ratio between the maximum and the minimum intensity will remain constant. This ratio can, however, be increased by the methods known as noiseless recording, which will be discussed shortly. The ground-noise is the sound heard from the loud speaker when the film is running through the projector, but there is no change in transmission of the sound-track except that due to parasitic modulation. When a well adjusted projector is running without any film at all and the amplifier is adjusted to give the desired loudness from a -25 -30 o z J-40 y I U-45 -50 -56 O — riNE. GRMN EIMUL-<=>\ON • MEDIUM SVZ.E. GRfMN ELMUL.. X— COURSE GR/MN EMULSION O.b 1.0 Z.S SPECULAR DENSITY FIG. 12. The relation between ground-noise and density. normal sound record, there is a slight residual noise arising from the photo-cell and electrical system, the level of which, however, should not be greater than 55 decibels below the maximum level of the sound record. If a perfectly clean film is allowed to run through the projector, the ground-noise increases about 6 decibels. If, now, the film carries a photographic density such that it transmits one-quarter of the light (this is the density normally used for an unmodulated variable-density sound-track) and if the amplification is increased to compensate for the reduced illumination of the cell, the noise level