Here's my first BiF photo posted here (I think), and one of the first ones I like from the Rf 100-500mm. This killdeer is one of a flock of a dozen or so that spends afternoons in a field near our home. They love to stay far away and usually fly just below tree-lines, but this one flew a little high and I was able to get a shot. I was only at 324mm because I needed a little extra field-of-view to keep it in my EVF.
I thought I'd try the much lighter 100-500 with the 1.4x TC after yesterday's outing with the heavy 400/4 + 2xTC. Here's a Skylark at 700mm f/10. These birds are very small and a decent focal length is needed but 400/500mm is easier to handle.
Trying out the R6 with 100-400l II and 1.4X III, but the only BIF today was the northern migration at higher altitudes. The locals were settled in on the pond so I did get some portraits.
One large bird did approach, just kidding. I post it because the R6 surprised me a bit. After drawing the focus around the entire "bird", the EyeAF kicked in and settled on the cockpit window. Which makes sense, I guess.