videofact

Most digital cameras have an optical zoom, which increases magnification via lens manipulation The image is changed before it hits the CCD so each pixel has unique information.

Resolution stays the same when the image is enlarged optically, which means the picture is still crystal clear. The quality of the optics is important because it determines the final quality of the photo.

A digital zoom is used to multiply the zoom ratio of a fully extended optical zoom.

Because the image is changed after it hits the CCD, pixelization occurs when you enlarge it. Essentially, a digital zoom isolates a sector in the center of the optically derived image and blows it up.

Since the pixels themselves are enlarged, the image doesn't gain any actual detail. The picture won't get any clearer, just bigger. In short, a subject's detail is actually captured more faithfully with an optical zoom than a digital zoom.