wcaptain

Hi there,

I used 40D + 300mmF4 (with IS) + 1.4x. Why 300mmF4? light enough. flexible - 300mm F4 at the Tai Po Kau forest (poor light condition) and 300mm F4 + 1.4x at Long Valley/Mai Po (better light condition).

Also 400/500/600mm F4 are bloody expensive. 300mmF4 + 1.4x are about $12k

I suggest you go to Tai Po Kau and Mai Po and ask the photographers' opinions. If you are lucky enough, you may try their lens there.

Captain