Concept: Cameras/3-D Cameras and Technology.

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A stereo camera is a type of camera with two or more lenses with a separate image sensor or film frame for each lens. This allows the camera to simulate human binocular vision, and therefore gives it the ability to capture three-dimensional images, a process known as stereo photography. Stereo cameras may be used for making stereoviews and 3D pictures for movies, or for range imaging. The distance between the lenses in a typical stereo camera (the intra-axial distance) is about the distance between one's eyes (known as the intra-ocular distance) and is about 6.35cm, though a longer base line (greater inter-camera distance) produces more extreme 3-dimensionality.

In the 1950s, stereo cameras gained some popularity with the Stereo Realist and similar cameras that employed 135 film to make stereo slides.

3D pictures following the theory behind stereo cameras can also be made more inexpensively by taking two pictures with the same camera, but moving the camera a few inches either left or right. If the image is edited so that each eye sees a different image, then the image will appear to be 3D. This method has problems with objects moving in the different views, though works well with still life.

Stereo cameras are sometimes mounted in cars to detect the lane's width and the proximity of an object on the road.

Not all two-lens cameras are used for taking stereoscopic photos. A twin-lens reflex camera uses one lens to image to a focusing/composition screen and the other to capture the image on film. These are usually in a vertical configuration. Examples, would be a vintage Rolleiflex or a modern twin lens like a Mamiya C330.

Cameras

There have been many types of cameras that take stereo images, most of which are no longer manufactured. The most notable types are:

• Jules Richard Verascope
• Kodak Stereo Camera Kodak's own offering in the field of Realist format cameras which actually outsold the Realist during the five years it was available and might have eclipsed it in all time sales had it been introduced prior to the end of 1954.
• Loreo 3D Lens in a Cap (Hong Kong) - an accessory device, which incorporates a pair of small closely spaced lens, and a simple mirror box as an attachment for many modern SLR digital cameras. The latest version has 25mm wider angle lenses. Loreo also makes currently, a cross-view 35mm film only, 3D CAMERA, (model 321) which takes "deeper" stereo images, with a wider mirror system, sold with a folding print viewer included.
• Nimslo 3D The first compact consumer level lenticular camera, designed to take 3D prints that are viewable without glasses or special technique. Though it didn't "catch on" and was soon discontinued, it inspired many 3 and 4 lens clones marketed well into the 1990s.
• RBT In the modern 3D world, a several thousand dollar RBT camera is made in Germany by rebuilding two 35mm high end cameras into an integrated & unitized stereo camera.
• Stereo Realist The original "Realist Format" camera, first sold in 1947, which inspired many imitators who introduced cameras capable of producing the 5P stereo slides which remain fairly popular to this day.
• View-Master Personal Stereo Camera Introduced in 1952, this camera allowed individuals to make their own personal View-Master reels, either by using the commercial processing services available at the time or by using the custom cutter and blank reel mounts.
• Fujifilm FinePix Real 3D W1, a digital stereo camera.

In 2009, 3D technologies experienced a resurgence, including stereo cameras, with continuing developments in plenoptic camera technologies, as well as the emergence of digital stereo camera products and the Minoru 3D Webcam.

Use of dual cameras

Modern low cost digital cameras, and even dSLRs, can be mounted in pairs, with both triggered simultaneously. For nonmoving images this can be done by pressing both camera actuating buttons simultaneously, but this is not sufficiently accurate for moving objects. Certain camera models can accept modified programming from an image chip, and the software to trigger a slave camera from a master has been developed as open source software.