AI-server for "small movements people photography"?

Any opinion on WHEN AI-server focus is better to use than "one shot focus"?

For example, people in small movements (slow walking)?

Or if you use max aperture (2.0) any movement could cause OOF...

Either you constantly press "focus" button or if you have AI you could just keep tracking...

Ideas, consensus, praxis? :>

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Canon 350D owner

I like it when panning.
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GT

mikael said:

Any opinion on WHEN AI-server focus is better to use than "one shot
focus"?

Click to expand...

A simple rule of thumb:

If it's moving or might move, use AI Servo.
If it's not moving and not going to move, use One-Shot.

Right... only thing that troubles me is the feeling that AI-server focus is much less accurate... else I might as well use it for all occassions.

This means that - for small movements - I might be better of with using "one shot" and pressing it an extra time...?!

Or do you guys feel comfortable enough with AI-server?

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Canon 350D owner

mikael said:

Right... only thing that troubles me is the feeling that AI-server
focus is much less accurate... else I might as well use it for all
occassions.

Click to expand...

No, AI Servo is just as accurate as One-Shot. Some people think that - at least with some lenses - AI Servo is MORE accurate because it continually rechecks the focus.

AI Servo only uses one focus point - if you have all AF points turned on, it will always start with the center point. This makes Evaluative metering a bit less accurate with AI Servo than it is with One-Shot and all AF points turned on.

Also, AI Servo will not "lock out" the shutter release. You can still take a picture even if AF has failed to focus on your subject. One-Shot will prevent you from taking a picture in this case.

Of course, AI Servo may refocus when you don't want it to. For example, if you have focused on something and somebody walks in front of your subject, AI Servo might refocus on that person.

For similar reasons, AI Servo is not a good choice for "focus and recompose". When you recompose, AI Servo might refocus on something else.

If it is a small movement and I got fast enough shutter I would just use 'one shot'. I would use AI servo for moving cars, airplane, etc that I have to track them along. Sometimes I use 'one shot' and do 'half press' a few times before I take the shot if they are not moving too fast.

I think AI servo is desirable when the subject is moving toward you or away from you.
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It's the Indian, not the arrow!

Ok, thanks guys! :>
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Canon 350D owner

Doug Pardee said:

mikael wrote:

Of course, AI Servo may refocus when you don't want it to. For
example, if you have focused on something and somebody walks in
front of your subject, AI Servo might refocus on that person.

For similar reasons, AI Servo is not a good choice for "focus and
recompose". When you recompose, AI Servo might refocus on something
else.

Click to expand...

This makes having focus on the thumb button great, since you can effectively decide when the focus system should be working and when it should not. focus and recompose becomes a non-problem with AI-servo mode.

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Japan: http://lucs.lu.se/people/jan.moren/log/current.html
Images: http://www.flickr.com/photos/jannem/