viewfinder(redirected from optical viewfinder)
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an optical device on still and movie cameras that is used for determining the borders (frame) of the image of an object that is being photographed. A viewfinder is de-signed for a camera lens with a fixed focal length. Cameras with interchangeable lenses having different focal lengths require the use of separate viewfinder attachments for each lens or of universal viewfinders, which consist of a set of miniature lenses with different focal lengths, mounted on a rotating disk. Types of viewfinders include the frame (iconometers), telescopic, and reflecting. Professional movie cameras often have mirror viewfinders with a mat collective lens and a sight.
Parallax, which is the difference between the borders of the image as observed in the viewfinder and as actually re-corded on the film, occurs when the optical axis of the viewfinder does not coincide with the optical axis of the camera lens. Parallax is especially great when photographing at small distances. A series of rectangular frames that permit corrections when photographing at various distances are mounted in the field of view of some viewfinders to eliminate parallax. Parallax is absent in single-lens reflex cameras and in movie cameras with a mirror shutter. In some cameras (for example, the FED and Zorkii) the viewfinder is coupled in a single unit with an optical range finder.
viewfinderThe preview window on a camera that is used to frame, focus and take the picture. On analog cameras, the viewfinder is an eye-sized window that must be pressed against the face. Point-and-shoot digital cameras use small LCD screens.
Professional photographers generally prefer a viewfinder because it lets them hold the camera steady against their face and focus on framing the picture without distraction. In addition, the LCD screen can be hard to see in bright sunlight.
Digital SLRs and Prosumer Cameras
Using optical lenses or a tiny microdisplay, digital SLR (DSLR) cameras employ an eye-sized viewfinder for taking pictures and an LCD screen to display the results. A "live preview" or "live view" on a DSLR means the LCD screen can also be used as the viewfinder. See DSLR.
Prosumer cameras have fixed lenses like point-and-shoot cameras, but they also have manual focus, aperture and shutter speed settings like DSLRs. Such cameras generally offer both viewfinder and LCD screen for taking the picture. See prosumer and parallax error.
|Viewfinder and LCD|
|This prosumer camera has both viewfinder and live preview screen. The viewfinder has two advantages. Since it is held against the face, it helps steady the camera, and it uses less battery than the LCD screen.|