I used to own the non-HSM version of that lens and found the AF to be a bit hit'n'miss on my a700 and a77. I think it's because at such wide angles, nearly everything is nearly in focus nearly all the time. I settled for using Manual focus using the distance markers on the lens. If you set 10mm, f8 and focus to about 2m, more or less everything is sharp from about a meter away to infinity. Welcome to the wonderful world of hyper focal distances!