I found that AF was more of a hindrance than a help when photographing my son. I just used 'follow-focus' and took plenty (and I mean plenty) of shots. Keep your eye in the viewfinder and on the subject at all times and manually adjust focus as the subject moves. You'll be surprised how quickly you get good at it. You don't necessarily have to use the focus points either; if your subject is compositionally off-centre, don't bother using the focus points and then recompose - that just wastes time. Use the whole area of the screen to focus wherever your subject is within it. Good luck and regards, B.