Digital Zoom Vs Optical Zoom
Many digital cameras and video camcorders allow you to zoom into the subject you're focused on from a wide shot, which shows a broad area surrounding your subject, into an extreme closeup that might show a very small part of it in exquisite detail. There are two common ways of achieving this effect: optically and electronically.
How Optical Zoom Works
You can think of a zoom lens as a continuously variable magnifying glass. As you twist its barrel (or push a button on the camera body), the lens rotates, changing the magnification.
Optical Zoom Ranges
Common magnifying ranges for optical zoom lenses are 3x to 12x, although some recent cameras have optical zooms as wide as 24x and even 37x.
How Digital Zoom Works
Digital zoom works by cutting out a small portion of the image ("cropping" it) and then magnifying that part of the image electronically. Because fewer pixels are being used to form the image, the image quality degrades. For example, using a 2x digital zoom on a 4 megapixel camera is (very roughly) analogous to using a 2 megapixel camera instead. The camera's electronics replace the "missing" pixels mathematically using a process called interpolation.
Digital Zoom Ranges
Some cameras have digital zoom factors of 100x to 300x, although the higher ranges produce images that are so degraded that they are not practical for most uses.
Which Method is Better?
Since optical zoom does not significantly degrade the image, most photographers prefer it over digital zoom. Digital zoom may be desirable in situations where it the mechanical noise created by an optical zoom lens would not be acceptable.
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