70-200 focusing advice needed

Hi all,

Quick question -

Typicaly I take photos of objects that dont move, or at the very least move slowly. This week tho I plan to photograph some cyclists and Im a little confused regarding which focusing option to use - AF Servo or AF Focus?

Also - anyone have any general tips or tricks to think about when photographing cyclists that maybe I havent thought about?

BTW - Im a 5DMkii user

In One Shot, a half-press of the shutter release will lock focus and exposure; if you want or need, you can then re-compose.

AI Focus defaults to One Shot, but will automatically go to AI Servo if it detects movement on the selected focus point.

AI Servo tracks focus automatically and sets exposure when the release is fully pressed.

There's been much discussion on this forum on the usefulness - or otherwise - of AI Focus. The concensus seems to be that it's a good idea, not very well implemented. Others condemn it as handing too much control to the camera

Given the nature of cycling, I'd have no hesitation on settling for AI Servo from the get-go.

Another tip - practice panning before the event. You can do this 'dry' with passing traffic. It takes very little time to keep your subject on the selected focus point. Then practice it for real. You'll be surprised how easy it is after about 5 minutes.

ETA - Since AI Servo uses a predictive algorithm, it needs a split-second to work out approach speed.

Use AI Servo. AI Focus is like the lazy version of AF options for people who just want to leave it on one setting and let the camera work out (and sometimes/often get wrong) whether the subject is moving or stationary.

And don't underestimate the shallow DoF - so use the outer points to pick your point of focus (i.e. cyclists face) as you don't want to end up with sharp torsos and soft faces.

And don't be a afraid of shooting wide - this was ~11mm on a 20D

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Cheers for the advice guys!

phreeky wrote in post #12706298
And don't underestimate the shallow DoF - so use the outer points to pick your point of focus (i.e. cyclists face) as you don't want to end up with sharp torsos and soft faces.

Oh, theres something I had not considered - typicaly I only ever use the center focus point and recompose after, in this case there will be no time to do that. Well....if nothing else it will be a learning experience!

That it will be.

Use AI Servo, focus on the back button only, if you haven't set it up that way, already.

Maybe get some practice in on cyclists, cars, whatever, beforehand.

bohdank wrote in post #12706368
Use AI Servo, focus on the back button only, if you haven't set it up that way, already.

intresting....I assume you mean the rear AF button - I was not aware I could set it AF function independently!?

Yes AF-ON.

It takes about a day to get used to it (not have to think about it) but you may find that you will never go back to having AF on the shutter button. The shutter button will still activate IS on the 1/2 press, alog with the AF-ON button.

CFnIV - 3 is how I have mine set.

Yup I agree with bohdank. I always use the back button as you are able to do both functions independantly. Stick to AI Servo, I read that the AF focus often misses. If you can change the speed of focus drop it to slow, you don't want it to jump to background and allow it to expand the number of focus points.

once you've got the camera set up, go out and practice. by the time it's time to shoot the bicyclists you'll be an expert.