I recently purchased and R7 had it out all day last weekend with my 500 F4 II. While I got a lot of really nice sharp shots with it I noticed that the AF was slow trying to lock on to birds sometimes. The next evening I was testing it out in the back yard by going back and forth from a fairly close object to on a bit farther away, the close object was about 20m away and the far about 40m. When going to the far object (a tree trunk) it snaps in pretty well, when coming back to the near (a stone fireplace) sometimes it snaps to but many times it jumps around a bit. I watched the focus ring and what it does is it move towards infinity first then back to the object. Sometimes coming back to the closer distance it would "chatter" a bit or not focus in at all. I then put my Sigma 150-600C on the R7 at 500mm and it actually focused much better and faster than the 500 also tried the 400 5.6 and that was better as well. I then put the 500 on my 7Dii and that focused perfectly every time, it would just instantly snap into focus every time. So the issue seems to be the R7 and 500/4 combo. I called cannon and they recommended sending the lens and body in to be adjusted but I am leaning towards sending the R7 back for replacement first. Was wondering if anyone here has experienced this with the 500 or any other long lens ?
As far as settings go no matter what I changed seemed to make a difference but I was mainly testing it in one shot mode, also tried Servo, with tracking off, subject and eye detect off, single point, IS off, focus limiter to either FULL or 10m to infinity. I updated the Firmware to 1.2.0 right out of the box and also tried resetting the camera back to all defaults. The light was relativity low the other evening but I just tried it again in some brighter light and it still jumps coming back closer.
