Is it me, or my 450D? Focussing and image quality

photonius wrote:

If you use all AF points, the camera more often than not, will select the closest one to the camera, which makes anything further back appear out of focus. If you have just a single person, you usually fill the frame quite well, so AF with many points will be ok. However, if you have two (or more people), your field of view will be wider, so you probably have foreground and background, and your camera could focus on the wrong spot.