I'm trying to understand to what degree image stabilization helps (or hinders) when I'm tracking a fast-moving object. Lets say worse case a fast unpredictably moving object, for example, a basketball player moving and jumping around the court in a game.
Basically, I would be hand-holding the camera and it would be prone to vertical, horizontal, and tilt movements.
I know that IS is great when you're taking a hand-held picture of a stationary object or scene. But what about my scenario? Would IS improve the motion blur from camera movement in this case?
Assume that I would be already be using a high shutter speed, say 1/1000, to freeze the subject. Would IS add anything to the result since I'm already using a fast shutter speed? (Or would IS actually makes things worse somehow, like slowing down the AF system?)
I pose this question because I'm about to purchase a 70-200mm F/2.8 L lens, but I'm trying to decide if I should save the money and go with the old non-IS version, or pay more than twice as much for the IS II version.
General reading around the web tells me that the IS wouldn't help at all, and that having a fast shutter speed should effectively cancel out both subject movement and camera movement. But when I look back at the thousands of shots I've taken, it appears that on shots when I managed to keep the camera still (the subject is moving within the frame), the results are sharper than when I'm moving the camera to track the subject. So I'm wondering if camera movement is causing image softness even if I'm using 1/1000 shutter speed.