Originally posted by CWyatt But if you don't use centre-point focusing - if you're using multi-point focusing, doesn't the camera's computer just choose one of the points over the others to focus the lens on?
There is this automatic mode where the camera selects any AF point that finds something in focus, but there is also a manual selection mode where you can manually select the AF point the camera should use to obtain focus. In this mode you can use the four cursor keys around the "OK" button to move the AF point selection around. One configuration of the "OK" button is to reset the AF point to the centre position (at least this is the case on the K100D).
I only shoot in this mode. The alternative of using the centre point and then recompose may
- result in misfocus when the DOF is very shallow (rotating the camera changes the distance to the point you are focusing on), and
- maybe too slow when you are tyring to capture something moving (e.g., a tennis player you don't want to have in the centre of the frame).
A potential disadvantage is that the AF points outside the centre, in particular the two outermost ones, may not work as accurately. But for me they work well. Definitely better than manual focusing without focusing aids, in my experience.