Interesting question. I used group autofocus on my Nikon D500. I had probably 10 shots in succession and of those two were OK. The G2 lens grabs focus pretty quickly but the focus plane probably wasn't far off where it needed to be when the owl flew by. It was getting dark. Neither shot is as sharp as I would have liked. I don't know the first version of the Tamron nor do I know Canon. I do own the Sigma 150x600 C and I feel I'm getting better results with the Tammy. But it's early and the jury is still out. I previously posted a couple other sets of bird photos here on UHH that I took with the G2. You might be interested in those as well.
AJFRED wrote:
A quick question re focusing. Were you able to use autofocus, or did you convince the owls to fly into a preset plane of sharp focus? I have the first version of that lens, and wide open at f/6.3 (as I recall) I have difficulty with autofocus. The camera is a Canon 5D-2.