Framing a shot with focus lock

Out-of-focus photo

Autofocus works by measuring the distance to the subject that appears in the center of the view-finder. When you don't want the subject to be in the center of the image, first position the subject in the center, lock the focus, then frame your shot.

A common error made when photographing two people is to focus on an object seen between them. This can cause the two people to be out of focus.

Better photo under identical condition

Compare:Understanding Digital Cameras/Differences between the image in the finder and the image that is actually saved