Quote Originally Posted by Jonathan Huyer View Post
That's great to know. I'm also keen on your experience with using the spot AF mode, when you have the chance to give that a try. It makes the focus box a lot smaller obviously, but it gives reduced performance when the light is dim or the subject is low contrast. I'm wondering if the spot-AF in the R3 gives better performance than the R5.
I did some test shots tonight on one of the lab pups. The test ended about 15 minutes after sunset and started just as the sun was setting. It seems the answer is yes the R3 is better and substantially so. I shot the 70-200mm at F/2.8, 1/100 and stopped shooting when the ISO went over 10,000.The R5 was gradually worse and more erratic, the shots were slightly OOF even when it hit. The R3 was still nailing shots all the way through. At the very end I turned on Animal/Eye detect on both. I didn't have time to switch the lens around so I used both one with the 24x70 at 70 and the 70x200 at 70. The R5 couldn't find focus, but the R3 could hit the eye although it was a bit erratic. Keep in mind I was shooting a black lab pup after sunset.

I know the pictures in the view finder are JPG's, but even the quality of the JPG's out of the R3 are better than those out of the R5. It also seemed like the R5 was struggling with metering and the R3 was not.

My R5 is still under warranty, I decided I am going to ship it back to Canon and have them check it out.