Almost all compact digital cameras come with zoom lenses. But there’s a big difference between optical zoom and digital zoom. When you use optical zoom, you take full advantage of your camera’s millions of pixels. When you use digital zoom, you’re reducing the capability of your camera’s sensor to a fraction of its maximum potential. One picture (bottom image) was shot with a 7.1-megapixel camera using 3x optical zoom. The other (top) was shot with the same camera using 12x digital zoom, effectively reducing the 7.1 megapixels of image data to less than 0.5 megapixels. The picture’s detail and color quality is greatly reduced, making it look softer. The lesson: Use digital zoom only as a last resort.

From the National Geographic guide to digital photography.

— Ken Geiger