7D AF setting question:

when I want the camera to track something across the frame, what settings do I need in terms of AF point selection and how it'll then hand it off to the points across the frame as the subject moves? I know I need AIservo. My example is with a static framing of a scene, but where something is moving across the frame. I DO NOT want to just use the same point.

The examples I have seen used Auto AF (all points) or Zone AF. I have not done it myself but I believe in the B&H videos they demonstrated this with a runner.

With the 1 series, when using AI servo and all 45 AF points, the hand off to other af points only occurs after the initial focus lock from the center AF point is made on the subject.

I say this only as I am not sure if you are hoping the camera can AF and lock on a moving subject coming in from one side of the frame and then moving off to the other side, without any panning. You will not get the initial AF lock on a subject that is not under the center AF point to begin with.

You can force it to start with an off ceter AF point, but to do this you can't use all 45 points, you need to specify the off center point for initial AF, and then use custom functions to allow "expansion" to neighboring AF points> With Expansion, you can use any AF point as the initial point, however this limits you to only a few AF points for the hand off, not all 45, so again, not clear across the screen.

I assume this holds true even with the 7D's new AF features.

I want it to start with a specified point though (top point in vertical) and follow the action through the frame though. Straight line down the frame, but the subject is coming closer...

For this example, it's my kid coming down a slide!

I haven't had any personal experience with this but according to the B&H video tutorial, you set it up as all-point (19) focus, but you can still setup the starting point to acquire focus. At least that's the way I remembered it on the tutorial video.

I just tried it out at home, instead of having a moving object, i just panned the camera. Yep. set it up as 19-af, ai servo, and you can select the starting point to acquire/lock focus and then then points will go along as you move.

On the 7D you can use the auto AF points, but you can also select a starting point. The 7D changes everything. You do NOT have to start from the center point like with a Rebel or 5D. You can start off center if you wish. Start there, and it'll track your subject moving. I played around with it a bit last week. I'm not sure how well it works in practice, but I'm sure it'll work.

I pretty much did what the above poster said and it worked fine (just panning in my room).

CyberDyneSystems wrote in post #10565091
I assume this holds true even with the 7D's new AF features.

No, it doesn't, neither with the 7D nor with the 1D Mark IV. They both allow you to use all points and start with any you like. But the 1D Mark IV doesn't track with all points, but with a "cloud" of 18 points surrounding the currently active point. When handing over, the cloud moves along with the current point, so it's effectively like using all points.
This is probably to avoid overloading the AF processor, and implies that the 1D Mark IV does the same job as the 7D in this case, since the 7D always has 19 AF points.

jwcdds wrote in post #10565337
I just tried it out at home, instead of having a moving object, i just panned the camera. Yep. set it up as 19-af, ai servo, and you can select the starting point to acquire/lock focus and then then points will go along as you move.

OK, how'd you set it up specifically?

servo I got, but do you turn on all 19 points or one to start? And is there a setting to tell it to hand off to others or what?

Thanks Julian.

I don't think there's any other menu options that you need to turn on. What I did was:

Switch AF to AI Servo. Then switched the mode to All-point. During this time, I see the entire AF frame light-up with the brackets (showing me that all-point is selected), but at the same time, there was 1 square that was also visible.

From that point on, I just half-press my shutter button and that frees up the single point and I moved it where I wanted it to be with the little thumb-joystick. And then from that moment on, that will always be the starting point of my AF-servo tracking. (until you decide to change the starting point with the joystick button again)

dmo580 wrote in post #10565377
On the 7D you can use the auto AF points, but you can also select a starting point. The 7D changes everything. ....

Cool!

jwcdds wrote in post #10565826
I don't think there's any other menu options that you need to turn on. What I did was:

Switch AF to AI Servo. Then switched the mode to All-point. During this time, I see the entire AF frame light-up with the brackets (showing me that all-point is selected), but at the same time, there was 1 square that was also visible.

From that point on, I just half-press my shutter button and that frees up the single point and I moved it where I wanted it to be with the little thumb-joystick. And then from that moment on, that will always be the starting point of my AF-servo tracking. (until you decide to change the starting point with the joystick button again)

yeah, I tried it yesterday w/o checking back and that's exactly how I got it to work too, it then tracked it across the frame.

So then how do you get it to pick points from all 19 again then? Halfpress again then just don't touch the joystick? (yeah yeah, trying this would answer the question ).

jacobsen1 wrote in post #10575852
yeah, I tried it yesterday w/o checking back and that's exactly how I got it to work too, it then tracked it across the frame.

So then how do you get it to pick points from all 19 again then?

Switch to one shot. All 19 will then be active again for closest/most contrast focusing.

just wondering, what are you trying to shoot?

Reevo wrote in post #10575941
just wondering, what are you trying to shoot?

Er....

jacobsen1 wrote in post #10565313
For this example, it's my kid coming down a slide!

gary luhm provides an excellent, detailed tutorial about AI Servo Focus at his site: http://garyluhm.net/bi​o/tips_0310.html