Tech Watch

When buying a digital camera, many people focus on just one factor: megapixels, the more the better. But that's not the whole story. Lens quality, image-processing capability and even the size of the pixels can all have a greater effect on how your pictures turn out. "The number of megapixels," says Bob Sobol, an image scientist at Hewlett-Packard, "is relatively unimportant."

What the quantity of megapixels (each one equals 1 million pixels) does determine is how big you should make your prints. For most consumers, a bottom-of-the-line, 2-megapixel model is just fine for producing great 4-in. by 6-in....