A report on sample binocular serial no. 6268 Mark I, Model 2.

Abstract

No significant differences were found between the performance of men using the sample rigid binoculars and the standard adjustable 7 x 50 binoculars under similar conditions. This conclusion is true not only of men whose focus and IPD approximated those built into the rigid binoculars, but also of those whose focal adjustments were divergent from those of the binoculars. There is evident a poorer performance on the part of men with IPD's markedly divergent from that for which the rigid binocular is set. The sample Interpupillary Distance Setting Gauge has been found to be a simple and effective method of maintaining IPD setting in proper adjustment. Its use is recommended. The focus and IPD adjustments which the average enlisted man makes for his eyes are highly variable and are not to be relied upon. (Author)