Stereoscopic 3D

Cinema, since its inception in 1895, has been three-dimensional: three-dimensional in the sense that there have been depth cues that can be appreciated by a person with only one eye. Filmmakers have learned how to control the monoscopic 3D effect by means of lens focal length, lighting, and additions of fog or mist to the background, a moving camera, and other techniques. But the stereoscopic cinema works only for people with two normally functioning eyes because it adds the depth cue of binocular stereopsis (two-eye solid seeing). The stereoscopic cinema reproduces retinal disparity when one looks at a stereoscopic movie with 3D glasses. Compared to planar photography, stereoscopic photography has two additional creative controls: setting the distance between the camera lenses or, more properly, lens axes (which control the strength of the stereoscopic effect); and controlling that which appears in the plane of the screen.