Yesterday I pushed my 5D with some wildlife photography by putting a 300mm lens with a 2x extender and initially setting it to an extreme ISO setting (3200). Normally, I do wildlife photography with a 30D, which uses a smaller sensor ("cropped") and makes it appear that you get more telephoto "reach". The 5D takes a bigger "field of view" but then I figured if I could get more reach for it, well, hopefully better pics!

The 2x teleconverter does add a little softness, especially at the fastest aperture, and it slows the f/2.8 lens down to 5.6, but, hey, it's all fun.

The afternoon's shoot is in my Nature gallery, the Ridgefield Wildlife Refuge entry for October 30 07.

Here's a few pics that show how ISO 3200 work on the 5D!