It's funny to see how quickly people jump in to attack sigma lenses saying that the problem lies in their lenses... From my experience, my d700 + sb-900 and any of my lenses will show this problem, mostly nikkors and my sig 50.
I really dont understand why it happens but I just know that it does, with all my lenses (some worse then others) so i just turn it off. As someone else stated, people get annoyed with that light anyway.
