Stereo or 3D Cameras
A twin lens reflex camera has two lenses, but a stereo or 3D camera comes with two or more lenses. The lenses enable a stereo camera to simulate human binocular vision. Because of this effect they are ideal for producing three dimensional photographic images or movies. On stereo cameras, the distance between the lenses is basically similar to the distance between a person's eyes. Many people may not have heard of these types of cameras but they have been around for over 50 years.
Years ago, the theory and selling point of these cameras was that it was less expensive to create 3D images by taking two photos with the same camera by moving the camera slightly to either the left or right. Stereoscopic pictures are made in pairs. The photos show the same scene or subject from slightly different angles just as your eyes do. If you edit the image allowing each eye to see a separate image, it will appear to be three dimensional to the human eye. Most stereo cameras use regular film and processing techniques. They also cost about the same as regular single lens cameras.