Gorgeous photos!I have been testing the Sony a9 versus my 1DxII. I am using the Sony a9 with my Canon glass (600mm f/4 IS II and 100-400mm IS II, with and without 1.4x teleconverters). I am using the Sigma MC-11 adapter. You might want to try it out. The a9 AF system is quite amazing and once it locks on to a bird it does not want to let go. I get more series of all tack-sharp images with the Sony than with the 1DxII as the 1DxII tends to give me sharp and a bit soft images intermixed as the AI Sero AF micro-adjusts during a long burst series. Moreover, the a9 EVF has no blackout what so ever. It is actually easier to follow a bird in flight while shooting with the a9 then with the 1DxII and its fast flipping mirror. There are of course limitations when using adapted glass, but for me it has been an interesting, and to this point, successful test. I do not at all like the Sony's ergonomics as compared to the 1DxII, but it is something I can deal with. Everyone is different in what they need and like, and you may not like the performance, but if what you need is simply a camera which you can track, with a 500+mm lens, a fast flying bird and get decent in-focus results, this combo will do it. Attached file all taken with the Sony a9 and adapted Canon 600mm f/4 IS II + 1.4x TC hand held.View attachment 184990View attachment 184991View attachment 184993