Editing Viewfinder

In antique cameras the '''reflecting type viewfinder''' is the most common means of image preview. It is not very reliable but easy to add to a folding camera's front standard or folding bed, or into the housing of a box camera. The [[brilliant finder]] is the most widespread of such finders, a combination of a lens, a mirror at a 45 degree angle behind that lens, and another lens at right angle position to the first one to view the mirrored image from the top. An older version was the small cubic ''Watson finder'' with lens and mirror as in the brilliant finder, but with a hooded matte screen for viewing the finder image. A special version was the ''Sellar finder'' which consisted just of a concave mirror with targeting aid. Old [[SLR]] cameras have a bright reflecting type finder with matte screen that uses the same lens as the camera uses for exposures. Before exposure the mirror is lifted so that the light coming from the image subject through the lens can pass towards the image plane where the [[focal plane shutter]] allows the exposure of the film for an instant. [[TLR]] cameras have a bright reflecting type finder with its own focusable lens, a "twin" of the camera lens, combined with mirror and matte screen. Thus a TLR finder is almost like a [[camera obscura]]. All these finders are to be viewed from above. Together they are the class of waist-level finders (or chest-level finders, such names resulting from the height in which a camera is held when the finder is used).

Other optical viewfinders of old cameras are placed upon the camera top as small rectangular "telescope". Since the 1950s these viewfinders were more and more integrated into the camera bodies. In older cameras the finders might consist of only the front lens and the [[ocular]] lens. The viewfinders' "telescope" optics are often more like reversed telescopes, giving an image of reduced size. These finders belong to the "reverse Galilean" or "Newton" type.

Modern zoom finders might be more sophisticated. More sophisticated are also viewfinders with superimposed [[rangefinder (device)|rangefinders]], and those with parallax correction. [[Parallax]] error is due to the fact that an optical system positioned parallel to the camera optics never gets the same image as the camera lens for close subjects. This can be corrected by moving the [[ocular]] slightly, or by some other provision to help make the finder image and taking lens image similar.

Finders of modern [[SLR]] cameras view through the taking lens and are completed with a [[pentaprism]] plus [[ocular]] or a mirror system plus ocular. With these additions the reflex finders become eye-level finders and enable the photographer to see the image like through a telescopic optical viewfinder, including any effects introduced by the lens itself or added to the lens.

Of course the inventiveness of camera developers didn't stop with the question "How can we combine the advantages of waist-level and eye-level in one finder?". One answer was a collapsible hybrid viewfinder. It had a front lens with crosshairs as a targeting aid, what was called ''Newton finder'' 100 years ago. With this combination it was an eye level finder. But when its crosshaired mirror was put in at a 45 degree position behind the lens it became a smart waist level finder. Smart because the crosshairs of the lens and that on the mirror helped to find the perfect perpendicular viewing position of the eye over the finder.

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