A Method of Measuring the Contrast Rendition of Telescopic Systems*

Abstract

A method has been developed by means of which the contrast rendition of telescopic systems can be measured using collimated light. The method utilizes an optical-electronic apparatus referred to as “the contrast rendition apparatus model 2” and is designed following the basic principles for such equipment as described in a previous paper. This apparatus is 60 inches long, 30 inches wide, and 65 inches high, and includes an assembly referred to as “the artificial sun.” This assembly permits the measurement of the contrast rendition of telescopic systems for the simulated condition of observation in which a bright luminous body may appear to be located near the region under examination. The contrast rendition has been measured for a number of prism and lens erecting telescopic systems for a variety of conditions simulating situations of intended uses for such optical systems. The numerical values of the contrast rendition were found to range from 0 to 93 percent for the optical systems studied.