AF Problem with S3
Try turning the camera vertical, lock focus and turn the camera back to horizontal then derpress shutter. Takes a bit of practice to hold the focus lock and turn the camera back before taking the pic. This works very well in hard to focus situations. The camera is trying to focus on a veritical line and sometimes it cannot. This tricks the camera into thinking there are vertical lines to focus on. Give it a try. Works 98% of the time.
Hooked on super zooms