What is the difference between an "optical zoom" and "digital zoom"?

What is the difference between an "optical zoom" and "digital zoom"?

Mark Comon (Vice President, Paul's Photo, Torrance, CA) gives expert video advice on: What are some helpful features my digital camera could have?; What are features of some digital cameras that I don't need?; What is the difference between an "optical zoom" and "digital zoom"? and more...

On a digital camera, there is a choice of two kinds of zoom. The first zoom is digital zoom. That's what you read about on the packaging. Twelve times digital zoom, wow! But that can produce bad pictures, because it's electronically blowing up the pixels. What you want to consider is the optical zoom, or how the lens moves. The optical zoom is the lens changing the focus, the lens bringing in, making things closer. So in the set up mode on your camera, number one, turn off the digital zoom. Number two, when you're buying a camera, ignore whatever digital zoom they claim to have and just look at the optical zoom. Optical zoom equals good pictures. Digital zoom euqals bad pictures.