I have a Canon XSi with the kit lens (EF-S 18-55 IS) as well as the 70-300 IS. I noticed on the 70-300 IS that I can see the effect of image stabilization when I press the shutter half way - I can tell the IS is turning on as the image in the viewfinder stabilizes. I have never noticed this with the 18-55 IS kit lens. Is it supposed to have the same obvious effect, that you can see through the viewfinder? Or has my kit lens had a broken IS the whole time? If you have the IS kit lens please let me know if it is supposed to be obvious like the 70-300 IS or if it's a different kind of stabilization.