In
photography, a
viewfinder is what the photographer looks through to compose, and, in many cases, to focus the picture. Most viewfinders are separate, and suffer
parallax, while the
single-lens reflex camera lets the viewfinder use the main optical system. Viewfinders are used in many
cameras of different types: still and movie, film, analog and digital. A zoom camera usually zooms its finder in sync with its lens, one exception being
rangefinder cameras.