Richardson's handbook of projection (1927)

Page scan 000378 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 #:
000378
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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826 HANDBOOK OF PROJECTION FOR I P* Hi* 6* Lie £ EUUiPTiCAL S f H£*ic*c ABC Figure 314A In figure 314A we illustrate the difference between spherical, elliptical and parabolic mirrors. EFFECT OF HOLE IN MIRROR.— While at first glance it might be assumed that the round opening in the center of the mirror through which the negative carbon passes would cause light loss, this is not true, because of the fact that, due to the tip of the negative carbon, little or no light could reach this part of the mirror, even though it were solid. The reason this dark spot does not show. on the screen is very simple. The face of the mirror is in focus out in front of (screen side of) the projection lens, as you may prove by affixing a bit of dark colored paper to the mirror surface and catching its image on a screen held the proper distance in front of the projection tens. Due to this fact neither the mirror or any obstruction, such as the carbons and their holders, can possibly be focused at the screen, the film plane being the only plane thus focused. It is governed by the same principle which prevents a broken