>I will experiment this weekend with increasing my shutter >speed to see if that's my problem. Would you say that >shooting handheld at 1/125, f8 would now be at least 1/250 or >more to get tack sharp images?
At f/8? I'd say 1/320s at least at any focal length up to 120mm or so. Faster still for longer focal lengths and smaller apertures. And much faster than that for any subject exhibiting movement