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. The viewfinder is an eye-sized window that requires the camera to be pressed against the face. All analog cameras have viewfinders but not all digitals have them. Professional photographers generally prefer a viewfinder because it helps them hold the camera steady and allows them to focus on framing the scene without distraction.
Types of Cameras
Many point-and-shoot cameras have only an LCD display for previewing the image. Prosumer and digital single lens reflex (DSLR) cameras have both the screen and a viewfinder, which can be an optical lens or a tiny microdisplay. The first DSLRs did not have a "live preview" and used the screen only to display images after they were taken. See DSLR, 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 uses less battery if the screen is turned off.|