I wanted to check how good the AF of the R6 works when combined with an EF400mm F5.6L lens, so I went to Shibuya and shot a few people crossing the famous spot (AF in eye tracking mode). I am happy to report that the focusing speed of the EF400mm F5.6L USM on the R6 is very quick and accurate. That lens was known to be very fast to begin with and as far as I can tell, it works wonders on the R6. I actually owned the EF300mm F4L earlier but couldn’t really use it to track fast moving subjects. Quite a different impression with the EF400mm F5.6L : very sharp and very fast. Too bad they stopped producing it a few years ago.