I went to an air show in Ft. Worth yesterday (pictures forthcoming), and this is what my neighbor on the fence line was shooting with. Pretty sure it's an EF 500mm f/4L IS II USM. You can get yours from B&H right now for the LOW LOW price of $10,499. What was really amazing was that the guy came up to the fence, set the camera down on its hood as you see it . . . . and walked away. He was gone for 20 minutes or more. And he did that twice. Just walked away and left $13,000 of kit sitting in the dust (that's just a guess, since I couldn't tell what the body was, but you wouldn't put that lens on a 20D).