AI Servo for Single Shot focus

[pcather]

I use back button focus and AI Servo when shooting wildlife. If a subject is very still while I’m in AI Servo I might focus and lift my finger from the button to freeze the focus.

I watched a recorded workshop from a very talented photographer. He was also using back button focus and AI Servo. But he said that he programmed a button that allowed he to toggle to and from Single shot. He did this when he had a still subject.

Since it was a recorded workshop I couldn’t ask him why he felt he needed to do this. It seems to me that focusing in AI and lifting my finger from the back button should achieve the same results.

I’d love to know if any of you have opinions on this.

[Waddizzle]

Which AF point(s) was the workshop photograper using?  Which AF point(s) do you use?

When I am in One Shot Focus mode, I use the [AF-ON] button for [AF-ON] with just the cener AF point.  This is the default behavior of the button.  I set the shutter for just metering start, whiich is BBF mode.

But, when I am in AI Servo mode, I use the [AF-ON] button for {AF-OFF], using the center AF point as the starting point for AF tracking, with all AF points active.  This does not work as well in Zone AF modes.

I save these two modes as Custom Shooting modes, each of which are based upon the Manual shooting mode.  When I am in M mode, I have used this button or another to switch between AI-Servo and One Shot.  This was a little awkward to use with BBF because now you have to press 3 different buttons simulatneously.

Like you, I often use AI Servo as a One Shot mode.  I do it by pressing [AF-OFF] when I press the shutter after having locked focus on the subject.  One problem with using BBF in AI Servo mode is that chaning AF points becomes awkward, if you wish to do so.  Leaving [AF-ON] on the shutter frees up your thumb to re-select AF points, adjust Av, or something else you need.

[pcather]

Thanks. Great insight. I’ll have to play around with these settings.

[jrhoffman75]

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@pcather wrote:
I use back button focus and AI Servo when shooting wildlife. If a subject is very still while I’m in AI Servo I might focus and lift my finger from the button to freeze the focus.

I watched a recorded workshop from a very talented photographer. He was also using back button focus and AI Servo. But he said that he programmed a button that allowed he to toggle to and from Single shot. He did this when he had a still subject.

Since it was a recorded workshop I couldn’t ask him why he felt he needed to do this. It seems to me that focusing in AI and lifting my finger from the back button should achieve the same results.

I’d love to know if any of you have opinions on this.

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It depends on whether or not your camera supports that custom setting.

Here is a cut from the 1D X manual:

[pcather]

Yes my camera has that function that I can customize a button to. My question is it necessary for me to actually switch to one shot. If I’m back button focusing in AI,  I am focused on the bird and I lift my finger, my understanding is that it no longer searches and will stay in focus, as long as the bird doesn’t move. Until I press the button again.

That is probably my question. While in AI does lifting my finger freeze the focus the same way as if I was in one shot? Or is there some reason why the focus will not be as good?

[Waddizzle]

Yes, you will get a result that is similar to using One Shot mode.  However, actual One Shot mode may be a little faster, and perhaps more accurate because there is no subject tracking taking place.