[siuman1984]

邊樣重要d呀???

[hylee]

Optical zoom is the magnification produced between the minimum and maximum focal lengths of the lens itself. In oversimplified terms, the magnification is from the (lens) glass, not from software inside the camera.

Digital zoom, on the other hand, is not a result of lens magnification. Digital zoom crops the image so the centre appears larger or more magnified. Predictably, digital zoom reduces the overall size of the image. Some cameras go a step further and interpolate the cropped image size back up to full-resolution size. In other words, the camera's internal software makes an educated guess about where to invent and add enough extra pixels to bring the image up to the size of a non-zoomed picture. The result with some interpolation programs is visible pixelisation (noticeably jagged pixels), while other programs produce smoother edges.

The results are always better when the lens (optical) does the zooming.

Source from:
http://photos8.msn.com.sg/editorial/EditorialStart.aspx?article=ChooseTheDigitalCameraThatsRightForYou§ion=FEATURES