Live preview is a feature that allows a digital camera's display screen to be used as a viewfinder. This provides a means of previewing framing and other exposure before taking the photograph. In most such cameras, the preview is generated by means of continuously and directly projecting the image formed by the lens onto the main image sensor. This in turn feeds the electronic screen with the live preview image. The electronic screen can be either a liquid crystal display (LCD) or an electronic viewfinder (EVF).
A Nikon D90 in live view framing mode
Live preview on LCD
Live view on a Nikon D300
A digital camera, also called a digicam, is a camera that captures photographs in digital memory. Most cameras produced today are digital, largely replacing those that capture images on photographic film. Digital cameras are now widely incorporated into mobile devices like smartphones with the same or more capabilities and features of dedicated cameras. High-end, high-definition dedicated cameras are still commonly used by professionals and those who desire to take higher-quality photographs.
Front and back of Canon PowerShot A95 (c.2004), a once typical pocket-sized compact camera, with mode dial, optical viewfinder, and articulating screen.
Hasselblad 503CW with Ixpress V96C digital back, an example of a professional digital camera system
At the heart of a digital camera is a CCD or a CMOS image sensor.
Digital camera, partially disassembled. The lens assembly (bottom right) is partially removed, but the sensor (top right) still captures an image, as seen on the LCD screen (bottom left).