Comparison of the Stereoscopic Range Finder, M12 with the Coincidence Range Finder, T43 (U)

One of the greatest needs in Armor operations is a reliable method of determining target distance (range). Two kinds of optical ranging devices are available, one using the stereoscopic principle, the other the coincidence principle. The stereoscopic device contains two reticles which may be fused and made to appear to recede or to approach the observer, the target image remaining stationary. The coincidence device shows the observer two target images which he tried to superimpose by mechanical means.