Woman Washing River Rocks Stereoview 1930s Keystone Rapids Stream Photo H1732 For Sale

"Changing Fixation from 7 to 1 requires 8 1.2 prism diopters of Fusional Convergence." (E. C. 10)

Published by Keystone View Company, formerly one of the largest stereoview publishers in the world.

This is a stereoview (also known as a stereograph or stereoscope card). It was one of the first forms of 3D photography. The images were captured with a special stereoscopic camera, which had two lenses - simulating the view of our left and right eyes. The two, nearly identical pictures were then mounted next to each other (most commonly on a piece of cardstock, glued on as photographs or printed as lithographs). The image could then be seen in three dimensions when viewed through a device known as a stereoscope, stereopticon, and/or televiewer.

Standard-size stereograph, measuring about 3.5 x 7 inches.