5d mk3 Ai servo and recompose at half pressed button

I don't use one shot nor BBF (although I have a back button assigned to stop AF), there's just no need for them on a 5D3.

I just use al servo, pick the right point and shoot for both still and moving subject.

Same here: permanent AI Servo, BBF, single AF point selected to suit, no recomposing.

Nick_Reading.UK wrote in post #16514396
Yes but many on this forum believe that AI servo is the best setting even with portraits as the subjects can move a lot..

For sure that's not right if you re-compose, so that your AF point no longer is on the subject.

bobbyz wrote in post #16515274
Setup separate points for horizontal and vertical shooting positions.

Already doing that..

bobbyz wrote in post #16515274
In addition program AF-ON button to use center AF point.

Good idea.. !!

so basically I was shooting our X-mas party and needed to shoot quick and be in Focus.. I did end up going to One shoot mode..

bobbyz wrote in post #16515308
Even with BBF if OP re-composes, he is messed up, isn't it?

Why? As explained above BBF and AI Servo work fine when recomposing.

Dan Marchant wrote in post #16515689
Why? As explained above BBF and AI Servo work fine when recomposing.

Just to clarify, BBF simply means transferring the 'AF Start' function from the shutter button to one of the back button.

I think what bobbyz meant was if one keeps holding the BB without letting go, the camera will refocus still when recomposing.

Dan Marchant wrote in post #16515689
Why? As explained above BBF and AI Servo work fine when recomposing.

I suspect that he meant that doing that, and releasing the button to recompose, isn't solving the issue of wanting to use AI servo and not one shot focus.

At the start, the OP was concerned about using one-shot and focus/recompose, which can cause problems at wide apertures, as the subject can go out of focus between locking focus and taking the shot. He wants to use AI servo because it continually focuses and can eliminate that problem.

Using BBF and recompose is essentially putting him back to square one, as it is the same as using one-shot. You can't use AI servo and recompose, even with BBF, the camera may be set to AI servo but as soon as you release the button, and lock the focus, you are no longer using servo.

Hence the comment from bobbyz that he is still messed up if he recomposes, as he is back to one shot and that was the problem.

Nick_Reading.UK wrote in post #16514490
True, I need to get quicker at moving my focal points...

How do you switch them now? Have you set the camera up to adjust them via the multi-controller joystick? Using the joystick is the quickest way to switch points around as you simply tap it in the direction you want it to move the point.

Provided you don't need too many of them, there's an even quicker method. Since you can register a certain AF point (called the Home Point, HP), and also program the AF-ON and * buttons to use AF with either the currently selected point or the home point, you can almost immediately switch between using two different points.
These setups can be done differently for verticals and horizontals, so you can have two points quickly accessible in both orientations.
By setting the joystick to switch back and forth between a selected point and the center point when you press it in, you can also quickly change the selected point between center and something else, in addition to the registered home point. This gives you three different AF points, accesible with one or two key presses, in each orientation.

Also check what abilities your camera has to switch AF setups, or even more settings in the camera, by just holding/pressing a button. The support for this in the 1DX is quite extensive, but I know it's a bit more limited in the 5D Mark III. You may still find something useful there.

bobbyz wrote in post #16515274
In addition program AF-ON button to use center AF point.

I don't understand why you'd want to do this. Center press on the multi-controller already does this(well toggles between center and last selected) and leaves Af-ON button for AF start or stop.

Which is precisely what I suggested in the post above your's. I think it's better too.

Well, I actually do want to know why. Maybe in the combination of other settings it does make perfect sense, but since I do things like above it doesn't to me.

lovemyram4x4 wrote in post #16516486
Well, I actually do want to know why. Maybe in the combination of other settings it does make perfect sense, but since I do things like above it doesn't to me.

Less movement of the thumb, from * to AF-On. I do wish I could use * for center AF and AF-ON for currently selected point though. But I think only 1dx allows that.

Several cameras support that, starting from the 7D (as far as I know - perhaps you could do it with some earlier 1D-series cameras too).

Why is the OP re-composing? Just move the focus point to where you want to focus. Then you don't have to worry about OOF anything whether in One Shot or AI Servo.

If the OP must re-compose, then set up the AF-On button in the back of the camera using Custom Controls to Start Focus/Meter. The next thing that the OP needs to do is remove Start Focus from the Shutter Button and let the half press shutter button just do metering and not Start Focus.