I took this with my 1d MK III and a new 100-400mm lens I just acquired. It was taken at 400mm, 1/1250 sec, f8, ISO 1000 and cropped quite a bit. The lens is about as sharp as a person could expect from a 4X zoom. Focus is ok at 400mm in good light, but with a 1.4 extender, it really struggles.


Here is a example taken this morning with the 1D MK III, 100-400mm + 1.4X. I used flash with a better beamer that just arrived in today's mail, so I was checking it out. You do lose sharpness with the extender, but the image prints very nicely on 8.5 X 11 paper, and woii also look good on larger sizes as well.


1/300 sec f/14, ISO 200