Richardson's handbook of projection (1927)

Page scan 00025 from Richardson's handbook of projection

Record Details:

Title:
Richardson's handbook of projection
Date:
1927
Publisher:
New York : Chalmers Publishing Company
Volume:
Richardson's handbook of projection
Leaf #:
00025
Language:
English
Subjects:
Motion Pictures, Motion Picture Technology
Collection:
Books
Format:
Books
Contributor:
Media History Digital Library
Sponsor:
Media History Digital Library
Coordinator:
Media History Digital Library
Description:
Date Added:
August 01, 2024
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MANAGERS AND PROJECTIONISTS 485 incident upon it." The brightness of a motion picture screen as viewed from any particular point is directly proportional to that particular value of reflection factor as. measured in the direction of observation. In the practical determination of the reflection factor it is customary to use as a reference standard a surface whose reflecting power is precisely known, since such procedure is much easier and simpler than the direct measurement of the reflection factor in absolute terms. The 5aaa>3«*a««. ..aaatiiaaa !■■■■■•. SURFACE B surface most commonly used for this purpose is that obtained by scraping a block of magnesium carbonate so as to obtain a perfectly smooth textureless surface. The reflection factor of such a surface has been measured with great care by a number of different observers in the national standardizing bureaus and in other research laboratories. A very general agreement upon a. value of 98 per cent for such a surface has been reached. This surface was therefore adopted as a reference standard in measuring the reflection factors of the screen surfaces reported herewith. The value quoted, 98 per cent, refers to the total reflection factor of this surface. The distribution of the reflected light from the surface is not perfectly uniform, hence the reflection factor determined by measuring with light incident normal to the surface and with normal observation must be slightly higher than the