I've never owned a lens with IS before. I think it may be broken, but I'm not sure. With IS turned on I move the camera a bunch and the same while shooting video and I don't seem to hear anything from the lens except AF and it doesn't seem to compensate for the movement. A few days ago I was trying to focus on a fast moving subject and I heard some grinding, it was the first and only time. Its the 18-55 IS III kit lens. Its a new lens that came with a new camera. Its about a week old. I'm not sure what to make of it. P.s. Should IS be turned off most of the time?