The 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.
Types of Cameras
Many point-and-shoot cameras have no viewfinder, only an LCD display for preview. Prosumer and digital single lens reflex (DSLR) cameras have both viewfinder and screen. The viewfinder can be an optical lens or a tiny microdisplay. Early DSLRs had an LCD screen to display images only after they were taken. See DSLR
and parallax error
Pros Like Viewfinders
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.
Viewfinder and LCD
This prosumer camera has both viewfinder and live preview screen. However, the viewfinder has two advantages. It helps steady the camera and uses less battery if the screen is turned off.