This is a test image that is handheld. The subject is about 35 yards away. The shot was taken indoors through a slightly tinted window. I believe f11 is the sweet spot for the manual focus of this lens. The wide open f8 is very difficult to manual focus.

This was taken with my Canon 20D. FWIW, my Canon 100-400mm IS L lens could've easily taken this shot and most likely produced even better results.