A Fast-Acting Exposure Control System for Color Motion Picture Printing

An illuminating system in a contact-printer for color motion pictures is described. Light from a single lamp is divided into three beams which are independently filtered, controlled in intensity, and projected onto the printer aperture. Intensities of the red, green and blue components of the exposing light are measured continuously and photoelectrically and compared with reference voltages which are the analogs of the desired intensities and which are controlled by a perforated tape according to the predetermined requirements of each scene to be printed. Any errors between measured intensities and desired intensities, i.e., between photocell outputs and reference voltages, are amplified and applied to servomotors which rotate vanes in the respective beams until the correct intensities are established. A response time of the order of 1/50 sec has been achieved, and the intensity of the printing light is substantially independent of lamp current and age. A manual control on each of the reference voltages provides for emulsion-to-emulsion variations in print stock.

Print ISSN

0898-042X

Published

1952-11

Content type

Original Research

DOI

10.5594/J04956