Real World Digital Video, Second Edition

Optical vs. Digital Zoom

Zooming is another name for changing the focal length of a lens, as when you zoom from wide angle to telephoto. Zooming is the first lens adjustment novice videographers learn, because it can add interest, even drama, to a scene—and it's easy.

Some consumer camcorders, especially low-cost models, supplement their limited zoom lenses with a digital zoom. For instance, if the optics of the lens only provide limited zooming range (say 10X), and you want to zoom beyond that, an image-processing circuit inside the camcorder selects a smaller portion of the CCD image area and enlarges it electronically. The electronic zoom involves interpolating pixels, a process that always sacrifices resolution.

Digital zooming makes it possible ...