It is very lightweight. Bazooka...they should use that in their ads! The lens hood is a good part of that though. The Sigma is about the same. I would think though you would not even need a tele converter with the 500mm though. You are effectively looking at 800mm on the long end. I haven't heard about the loss of AF on the Canon. With the 7D you should pick up a few stops with the ISO if needed too. Beyond early morning and late evening, lighting should not be an issue. A monopod will make a huge difference. It balances great especially with the tripod collar.
