Upload & Sell: Off
I noticed last night that I was getting severe front-focus with my 5D3 & 24-70ii. This after spending hours getting to know how to AFMA and fine-tuning AF.
It seems that the reduced area of the Spot AF point can see things differently than can Live View AF in 10x mode.
After trying to blow out the back of the main mirror, the small secondary AF mirror, and the AF array (can't really see this, but blew a lot of air thru the interior with the main mirror slightly raised, I am seeing better results. I should point out that I stumbled across this 'fix' when, after 3 attempts, Canon couldn't get my 1Ds and 3 lenses to AF consistently. I haven't had any noticeable sensor dust...
I'm wondering if anyone else has noticed a difference between these AF modes?
In doing these tests (with a Manfrotto 3021 Pro and a 410 geared head), I also saw that there is *always* a slight amount of image blur from the mirror motion, vs Live View mode. Something to think about if you need pixel-level sharpness. I also used the quiet-mode shutter. I need to test if I can use mirror-lockup when shooting astro...
Unlike everyone else, I AFMA (by shooting a 13" x 19" white sheet with a 1" thick line thru the center) by watching for distance scale movement while changing from LV to AF point. I find this method to be very quick (minutes) and as accurate as is possible.