@kvbarkley wrote:
It shouldn't, that is why you need the panning modes.
Oooof! Panning Modes. I'm not aware of my 60D or my few Canon lenses having any of those. So I'll have to do a bit research on those. Though I did find a little discussion on the matter on the Ugly Hedgehog photography forum. Just unsure if this applies to the OP's situation or not.
...There is no single "best" mode. It depends upon what you are doing and how you want the IS to work (how you want the image rendered, in some cases).
Mode 1 - Standard dual axis stabilization. Both horizontal and vertical movements are being corrected. Starts and runs normally with half press of the shutter release button or when the AF On button (or other assigned button) is pressed during BBF. Both the image in the viewfinder and the image being captured are stabilized. I usually like the viewfinder image being stabilized, so this mode is the one I use most of the time.
Mode 2 - Single axis "panning stabilization". Only movement along the vertical axis is corrected. And it doesn't matter the orientation of the camera. That's detected and the stabilization changes accordingly. This mode is used when panning with a slower shutter speed, where you are trying to deliberately blur movement in the horizontal axis and don't want the stabilization counteracting your efforts. It starts and runs the same way as Mode 1. And it effects both the viewfinder and the image.
Mode 3 - Instant dual axis stabilization, same as Mode 1, except this only starts and runs during the actual exposure. Unlike Mode 1, it doesn't start up as soon as you half press the shutter release (or press a button on the back of the camera using BBF). Stabilization doesn't occur until during the actual exposure, which can be a fraction of a second, so this lens' stabilization must be extremely fast acting. This mode basically doesn't effect the viewfinder image... only the image being captured. It also might be useful in extremely quiet situations, where the slight noise of the IS running would be heard (of course, your DSLR's shutter and mirror are still making noise). In certain situations, the IS stabilizing the viewfinder image might be unnecessary or unhelpful, too. Mode 3 also might save a little battery power in some situations, though in my experience IS doesn't draw a lot.
The 100-400 II is the least expensive lens to have this advanced form of IS, which is good for 3 to 4 stops of effectiveness (varies with user capabilities and other factors). The "II" series "super telephotos" (300mm f/2.8, 400mm f/4, etc.) are the other lenses that have Mode 3/Instant IS.
