I think I may try that in December when I'm there - use a fast shorter prime instead of the zoom. I only had my 70-300mm F4.5-5.6 zoom with me when I shot the safari, so the reach was perfect but it was a bit slow. I did set the Auto ISO to 100-51,200 and set min. shutter speed to 1/500 so it would at least TRY to maintain that shutter speed...though it was so dark that it had to drop down below the min shutter setting because even at 51,200 it couldn't get enough light. That's where the F4.5 was hurting me - so if I use an F1.4 or F1.8 lens, even if I don't get the reach, it should help with the shutter speeds at least. I believe we were moving very slowly with the wildebeest - not stopped, but slow and smooth enough to let me focus on them and not get bumped around too much.