I'm doing some AF tests using the 600, nothing controlled though, as I like to test how I shoot: handheld from a stable position, just like if I was photographing a bird in the field. I'm shooting on 10FPS until the buffer fills, usually getting 27-31 shots; doing multiple runs of each of the AF modes (Spot, Single, Zone, Large Zone, Auto), and AF'ing on fir tree bud about 30' distant with no distractions (background was a mile away). I'm standing braced against a wall, strap is tightened to give extra support.
These are just loose observations after 3-4 runs of each mode, but it doesn't take much to see trends start to develop:
- On average, the 90D is completely blowing focus on 4-7 shots per set. When the shots are missed, I am talking about "what the heck did the camera focus on" missed.
- These occur at random clumps in the burst, 13 sharp, 3 completely OOF, another 8 sharp, 1 more slightly OOF, etc.
- Single AF perform the best, giving me the most shots before the buffer fills, and only missing 2-3 shots.
- Spot is slightly worse, with an average of 3-5 misses.
- Zone, Large Zone and Auto fill the buffer quicker, and have the most misses. I don't use these modes very often, so they may require additional settings considerations that I am not aware of.
I'm tweaking AF now, going to try setting Release Priorities to "Focus", and AF Point Switching to -1 (or whichever makes it stick the longest). iTR has been turned off since I got the camera.