Sony FE100-400GM bird, A7R3 can also use S35 frame to lengthen the focal length, the photo has 5000 long edges, but the focus is not as fast and accurate as A9. The size of the S35 picture is too small when A9 is used for fast focusing but 400 ends are not enough.
In flight, A9 can still be captured. A7R3 can not be captured.
