I shot the Seahawk game yesterday, the af with the 400 sony 2.8 I paired with the 1.4 extender all day my other a9 had the sony 100-400 on it. That first shot you pray in a burst is in focus and with my canon 1d x mk11 and latest 400 2.8 Lis vr 2 might not be sharp with sony it was sharp. In a burst where one or tow canon shot smight lose af witht the osny it did not. All shots in a burst were sharp. I have not shot with a D5 but all canon af since the late 80s .. The A9 with the 400 was the best af performance I have ever seen.