(under the class definition) Subject matter including a rectifying element in the optical path, or means to adjust an element in the optical path to offset the undesired effects of abnormalities of the film or slides or undesired effects of the screen and projector alignment.
(1) Note. This subclass 69 has means to compensate for warped film or for film or slides of different size, thickness or density so that an undistorted image of the object on the film will be focused on the viewing screen; while indented subclass 70 has means to compensate for the projection axis being inclined to the viewing screen.
SEE OR SEARCH THIS CLASS, SUBCLASS:
76, and 101, for a projector with focusing means.
104, for a slide changer adapted to transfer slides of various dimensions.
SEE OR SEARCH CLASS
352, Optics: Motion Pictures, 140, for motion-picture projectors with focus control.
