What Is Optical Zoom?by Fred Decker
With traditional film-based cameras, your ability to enlarge or "zoom in" on a scene was determined entirely by the lenses on your camera. With modern digital cameras, that's no longer the case. Because the image is recorded digitally, it can also be zoomed digitally, just like you can enlarge a Web page on your computer's screen. However, the power of your camera's lens -- now called "optical zoom" -- remains a crucial factor in picture quality.
More Is Better
Most digital cameras give two numbers for their zooming ability -- one for optical zoom and one for digital zoom. The optical zoom is the more important of the two, because it determines the quality of the original image. A camera with 20X optical zoom can get much closer to its subject than a camera with a 10X optical zoom. You can magnify the 10X image with digital zoom to give a comparable appearance, but the resolution will suffer. If you later need to enlarge the image for printing, its quality will be noticeably inferior, and it will lack sharpness and detail.
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