I recently replaced my R with an R6II, and have been enjoying testing it out on various subjects. I got a chance to try it on field sports yesterday, with the RF 100-400. The Colorado women's lacrosse team was playing San Diego State, and, unlike for men's football or basketball, attendance is free. Anyone can just walk up to the outdoor field and take shots from the sidelines. I watched most of the second half, and found the combination of R6II and RF 100-400 to be excellent. It's so small and light (and cheap) that I felt comfortable holding it unaided the whole time. The official photographers were using big white lenses, and needed monopods to hold them up. The weather was good, so my ISO stayed in the 200-800 range, with a shutter speed of 1/2000 (I shot manual with auto ISO). The AF is simply amazing on this camera, and the speed is almost unbelievable. I stayed at a mere 20fps shooting in e-shutter, and had to cull a huge number of shots. From watching one of Jared Polin's test videos I got the idea of using single point with 4 surrounds to initiate AF, and had it set to human face and eye detect. It grabbed the eyes almost instantly, unless they were obscured, in which case it usually grabbed the head. Even in much darker conditions, this combination would be fine. Shooting cRAW and processing with DXO Photolab 6, I'm happy going all the way up to ISO 51,200 on the R6II. Here are a few samples:
A big white would give more background separation, but I actually like having enough DOF that you can make out the expressions on the other players' faces. I think the 100-400 on full frame is pretty much a perfect range for field sports like lacrosse or soccer, when you can be close to the sideline. I used it on my R7 a few months ago to shoot an informal soccer game, and it was actually a bit too long at times, even at 100mm. In case you're interested, Colorado won the lacrosse game 17-4.