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

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 #:
000297
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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262 HANDBOOK OF PROJECTION FOR but at 10 degrees it has lost 1/10 of one per cent, of its brilliancy. At a 15 degree angle it has lost 2 per cent, of its brilliancy as viewed from straight in front or at an angle of 5 degrees. At 20 degrees its brilliancy drops to 96.9, or a bit more than 3 per cent., and so on until at the extreme angle of 70 degrees it has lost 21.2 per cent, and has 78.8 per cent, of the brilliancy shown from straight in front. On the other hand, taking surface No. 8, which we see by Table 11, is a sandblasted mirror, we find that from straight in front it has Figure 76, a reflective power of 473 as compared with 100 for magnesium carbonate. In other words, the sandblasted mirror has reflective power almost four times that of magnesium carbonate when viewed from directly in front. If, however, we examine it at an angle we find that up to and somewhat beyond a 20 degree angle it retains its superiority over magnesium carbonate, though in rapidly decreasing percentage, but that somewhere between 20 and 30 degrees it drops below the magnesium carbonate, and at 30 degrees it has only