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| p.1 #14 · Need Help with Auto-Focus Servo jumping focus (1D Mk IV with 300 2.8 USM) |
What you're describing is a bit odd sounding. One thing for sure, moving from f/5.6 to f/2.8 IS going to seriously effect where focus lands. Fact of life with a bigger aperture.
Like others have suggested, I (on my 1DIV) set AF point to center only (also metering to spot), no assist. I've played with C.FnIII (2) trying slow to middle and can't seem to tell for sure. All the way to slow is worse, but the other settings don't make a significant difference. (I've never gone above middle.) I also keep C.FnIII (3)=0, C.FnIII (4)=1, C.FnIII (5)=1, C.FnIII (8)=1. I do fairly well shooting FB on a very dark field and attribute most OOF to idiot (user) error, though admittedly in the dark focus acquisition is always a challenge.
Dig into the manual and experiement.
BrianO, do you really have the presence of mind, manual dexterity to switch AF points while a play is developing? I'm impressed. How do you do it?