Hello, I'm looking to basically complete my lens arsenal this fall and would appreciate any advice. I currently own a Canon 10-22, Canon 17-40 and a Sigma macro 105. I'd like to complete my range of focal length for up to 400mm, and here are the two paths that I foresee, granted that I have just over a $2,000 budget this fall... Scenerio 1: Purchase the Sigma 70-200mm f/2.8 and Canon 400mm Scenerio 2: Sell my 17-40mm and purchase a Canon 24-105mm f/4 and Canon 100-400mm f/5.6 Scenerio 1 would give me a gap between 40 and 70mm (albeit the "normal" range thats not that important to me)... however it would give me a sharp 2.8 constant aperture lens and the canon 400mm prime versus zoon. Scenerio 2 would give me more versatile zooming in 100-400 but may not be as sharp. After selling my 17-40 in scenerio #2, both options would be about the same cost. Thanks for any opinions and advice! update: "upon further review"... since my body is a 40D, and I'm totally in love with this camera and won't be trading for a full frame anytime soon... I've decided that a 300mm f/4 L IS will be good enough for my needs since I have a 1.6 crop factor and I'm not as interested in shooting birds as much as I am deer, bear, bison, elk, fox, coyote, etc. Plus the ability to add the 1.4x to create a 420mm f/5.6 sounds great to me. For the shorter range, I'm afraid I'll have to settle with the Sigma 70-200mm 2.8 versus a Canon design since that will max my budget.... but I've heard of many having great luck with the Sigma.