James,
do you have the OS version of that lens? I've tried to stick with lenses that I'll be able to hand-hold and for me, IS is absolutely necessary at that focal length.

The other issue for me is the price. I can get either of the Canon lenses used in excellent condition for around $1,000. The best used price I've seen on the Sigma OS version is around $2,700. I'd have to see a LOT better IQ out of that lens to spend the extra cash. And it would have to be just as portable as the 300L and the 100-400L. Yes, the F2.8 would be really nice but not all that necessary for the type of shooting I'm planning to do with it. Maybe for fun I should rent it and see how it compares and then post my impressions here. Gives me a great excuse to get it in my hands and see how it works for my wildlife excursions.

I'll let you know what I find out. wink

Jim

Jim Garvie
www.jagphoto.biz