Refers to techniques used to produce the appearance of three-dimensionality in photographs by using two images made at slightly different positions, mounting them side by side, and viewing the pair through a stereoscope or other device. This type of photography was extremely popular in the Victorian period. The process was described in 1832, but the techniques were perfected only after 1856, when a twin-lens camera was designed to take two pictures of the same scene simultaneously. The viewpoints of the photographs were 2 1/2 inches apart, which is approximately the normal distance between human eyes.
