Handbook of projection for theatre managers and motion picture projectionists ([1922])

Page scan 000904 from Handbook of projection for theatre managers and motion picture projectionists

Record Details:

Title:
Handbook of projection for theatre managers and motion picture projectionists
Date:
[1922]
Publisher:
New York, Chalmers
Volume:
Handbook of projection for theatre managers and motion picture projectionists
Leaf #:
000904
Language:
English
Collection:
Books
Format:
Books
Contributor:
Gerstein - University of Toronto
Sponsor:
MSN
Coordinator:
Media History Digital Library
Description:
14
Date Added:
July 19, 2022
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MANAGERS AND PROJECTIONISTS 869 regular line voltage switch at "LOW" as soon as table switch is pulled. COMPARISON OF CRATERS.— The General Electric Company has provided us with the data needed for intelligent comparison of the ordinary and the high intensity arc. This data is found in the following table, which is self explanatory, insofar as undertanding its data goes: Avg. Ft. Crater Crater Lumins Candles on diameter Depth in Beam Screen Kind of arc Amperage Low 50 Intensity Low 75 Intensity Low 100 Intensity High 50 Intensity High 75 Intensity High 120 Intensity Carbon diameter .47" .12" .17" 1035 5.83 8.77 .27" .55" 1480 12.55 .05" 1437 12.2 .11" 2700 22.9 .48" .34" 4950 41.9 3/4 Pos. 5/16 Neg. 7/8 Pos. 13/32 Neg. 1" Pos. 9/16 Neg. 9 mm Pos. 9 mm Neg. 11 mm Pos. 11 mm Neg. 13.7 Pos. 11 mm Neg. Condensers used for tests 6l/2 and 7y2 piano convex. Projection lens 5" E.F., 1 7/16 Dia. Speed F 3.4. Screen 9' 7" x 12' 4". NOTE.— 1 mm equals .03937 of an inch. This data was received after the rest of the high intensity data was compiled. It is interesting to observe the great difference in carbon size and crater diameter. v For equal amperage it will be observed that the crater diameter is but little more than one-half for the high intensity. This should enable the projectionist to retard his condenser, use a short focal length condenser and reduce the beam divergence beyond the aperture to a value which will enable the projection lens to pick up the entire beam from a 120 ampere arc, a thing which will be highly beneficial in more than one way. ARMS AND LEGS ARE CHEAP - USE YOUR BRAINS.