David Pogue's Digital Photography: The Missing Manual

The Blurry-Background Portrait

In most professional photos of people, animals, or objects, the background is softly out of focus. In fact, that's one of the first things you might say when explaining the difference between an SLR and a pocket cam: "SLRs can keep the person sharp but the background a little blurred."

In technical terms, what you're looking at is a shallow depth of field. That's a geek-shutterbug term meaning "which part of the scene is in focus, front-to-back."

When you shoot with a pocket cam, pretty much the entire scene is in focus: the people, the ski lodge behind them, and the mountains behind everything. When you shoot with an SLR, though, you can keep the people in sharp focus, but blur the ski lodge a bit, and blur out the mountain into a mere suggestion. You can, in other words, set up a shallow depth of field.

(Of course, you can create a deep depth of field with an SLR, if you like. And it doesn't always have to be a blurred background; blurring the foreground is very effective, too, if it's not the subject of the shot. Or, what the heck—blur both the foreground and the background.)

Why is the blurry background so effective? First, because it's cool-looking; it's ...