DaveG wrote:
I don't understand how IS helps you here.
The 70-200 is effectively a 112-320 mm lens. At 320 you shouldn't handhold it below 1/focal length, which is either 1/250 or 1/500 depending on how conservative you want to be. Now with IS you'll get two stops below that, say either 1/60 or 1/125.
So have the football players stopped running? As I said in an earlier comment it isn't camera movement that's the issue here, it's subject movement, and those shutterspeeds are too slow to freeze action.
Exactly. I have found that when there is movement, I get cleaner shots with the IS turned off. I'm not sure of the mechanics of why, but the IS system seems to have specific uses and if I'm shooting something outside those uses (i.e., not panning, not stabilizing for low shutter speeds) the shots will be slightly softer if the IS is active. There really isn't much of a use for IS with action shots unless I'm in "panning" mode and actually using a panning technique. It certainly will in no way compensate for low light when trying to stop action, because as Dave mentioned, a minimum shutter speed of at least 1/250 is needed stop action, and I prefer the safety of a bit faster than that personally.
The IS can't work miracles. It is simply another tool for specific conditions.
David