This seemed too far for the 500mm on the Canon 40D so I used the camcorder with the above lens. I estimate the range to be between 50 and 75 yards or 150 to 225 ft. I had more or less written this lens off for use with the High-Definition camcorders, but have been using it again lately and have been surprised with the results. This combination of lens and High-Def. camcorder doesn't compare to a DSLR for picture quality on still shots, but I doubt that it is possible for the DSLR to do this well on a small bird at that range, even with severe cropping. If I get another opportunity, I will test it and find out.