Transactions of the Society of Motion Picture Engineers (1925)

Record Details:

Title:
Transactions of the Society of Motion Picture Engineers
Date:
1925
Publisher:
New York : Society of Motion Picture Engineers
Volume:
Transactions of the Society of Motion Picture Engineers (1925)
Leaf #:
000494
Language:
English
Subjects:
motion pictures, Cinematography -- Periodicals
Collection:
Technical Journals
Format:
Periodicals
Contributor:
Library of Congress, MBRS, Moving Image Section
Sponsor:
Library of Congress, Motion Picture, Broadcasting and Recorded Sound Division
Coordinator:
Media History Digital Library
Description:
Preceeded by an unnumbered issue published in 1916 called: Incorporation and by-laws
Date Added:
November 10, 2022
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96 Transactions of S.M.P.E., March 1926 celeration or retardation of development at the point of contact of the film with the slat. Experiments have shown, however, that more development occurs where the film passes over the slats even when the rack is cooled below the temperature of the developer before immersion. It is now known that rack marks are caused by non-uniform development due to convection currents and retardation of development of the film along the sides of the rack by the developer exhaustion products. I J TOP OF RACK BOTTOM OF RACK Fig. 1. Typical Development Rack Marks on Motion Picture Film In order to demonstrate the non-uniformity of development at the top and bottom of the rack a length of motion picture film was given a uniform exposure and developed for the normal time, five minutes, at 65° F., the rack being kept stationary. The density of the developed film was measured in several places at the top, middle, and bottom of the rack and the average measurements were found to be as follows: Top of Rack Middle of Rack Bottom of Rack ' 1.32 1.15 1.02