« on: September 07, 2014, 09:17:50 PM »
I sometimes use all 45 points in AI Servo, I just start with the center point and "walk" the subject out, but doing that you have no control over the AF point actually used, it just goes where the subject is and truthfully isn't selectable. Normally I use 19 point in AI Servo and One Shot.
Interesting that you get better results with the 45 set, I am amazed that you can scroll through the full 45 and do focus-recompose, I will often select an edge AF point before even lifting the camera to my eye for focus-recompose, I just select the closest point to the eventual point of focus.
I pretty much exclusively shoot birds and the 45 point set works well there. I lock focus with the center point and let the system hand off the active points as the bird moves through the frame. Most species are small enough that it doesn't matter if I get a point directly on the eye, but for subjects that fill the frame enough for this to be necessary a selectable point is only a few nudges of the joystick away. For distant subjects I use center point and crop in post. I only ever use AI Servo.
Yes, but that is how Auto Select AI Servo works whether you have 45 points selectable or 19 points selectable. If you have 19 points selectable it will still use all 45 points in Auto Select AI Servo, where it hands off to the next AF point, and it will always start from the center one.
19 point with expansion just gives you ability to control framing better in AI Servo and enables the linking of spot metering to the AF point, without degrading the 45 point handing off mode you can always default to at the push of a button .