AI servo and Image Stabilization

[T.O.]

I understand that AI servo won't work properly if you use it with a IS lens and IS is on.

When I use my 17-85 IS USM with One shot and AI focus it works just fine, then I switch to AI servo and it doesn't really work. I switch the IS off and AI servo works perfectly.

Is this exact? Is there an explanation?

kind regards,
T.O.

[kram]

I'm just thinking aloud here - some expert could confirm if this is right.

AI Servo and IS work exact opposite to the same stimulus - if there is movement, IS tries to correct for it. And AI Servo assumes its the object moving and hence adjusts focus.

If both are attempted, AI Servo would get jumpy movement through the IS on the lens. And it would correct focus which would throw IS out of the loop??

[sony23]

I dont think that sounds right, I use AI servo and IS for sports and the pictires come out really sharp, 70-200 IS mode 1 that is, while the AI servo is tracking the cars movement the IS is stabilizing the picture, I dont know if it is different on other lens's but it works ok on mine.

Bruce

[defordphoto]

AI Servo and IS work totally independently of each other. Also, there are two types of IS on L-lenses. One for stationary objects and the second for panning. AI Servo is in camera. IS is in lens. They don't talk to each other. We use IS and AI Servo all the time when shooting motorsports.

[T.O.]

Sorry guys,

I have made a terrible mistake here, still not vey familiar with my digital baby...

So, the IS DOES work perfectly with AI servo,

it is the AI focus that it does not work when IS is on!

To put it otherwise, the camera won't switch automatically from One Shot to AI servo when IS is on.

Sorry again, any answers to this (correctly formulated) question?

thanx a lot,
T.O.

[Jon]

IS should have absolutely no effect on any focus-related functioning of the lens. The IS feedback mechanism is in the lens; the AF feedback mechanism (including the circuitry needed to implement AI-AF) is in the body (note: this is not the same as "the focussing motors are in the body", which they aren't).

[defordphoto]

Sorry guys,

I have made a terrible mistake here, still not vey familiar with my digital baby...

So, the IS DOES work perfectly with AI servo,

it is the AI focus that it does not work when IS is on!

To put it otherwise, the camera won't switch automatically from One Shot to AI servo when IS is on.

Sorry again, any answers to this (correctly formulated) question?

thanx a lot,
T.O.

AI Servo and IS work totally independently of each other.

So, the answer is yes, IS and AI Servo work nicely together. Could be a possibility you're not undertsanding fully was AI Servo is, which is common. (I read your deleted post) ;)

[T.O.]

Thank you RFM sports!

OK, sorry for messing things up...I may not have a big experience with digital but I do have an experience with photography, so my overall understanding is the following:

AF one shot is the basic stuff, the camera autofocuses and "blocks" the AF

Af servo is suitable for moving objects, and the AF "follows" the movement of the subject

In the AF focus mode, if the subject is still and then starts moving, the camera "jumps" to AF servo in order to keep the subject in focus.

And I know of course that IS in in the lens and AF in the camera.

BUT, I insist that the AF focus does not work correctly when I have the IS on...is this normal, or you rekon that I have a problem with my camera/lens?

I guess that I do not, because with the IS off my AI focus works perfectly! All I want is to understand why this is happening, I am actually in the process of understanding the digital world so everything seems imporant to me.

If you're bored with this thread, I understand...
:)

thanx again,
T.O.

[Jon]

What do you mean by it "does not work correctly"? A couple of examples might help us understand, and diagnose, your problem.

[T.O.]

Thank you Jon,

actually I mean that it does not work at all. Let's say that I have a subject in focus (in AI focus mode) and I start moving, the camera won't change the focus if the IS is on.

If I switch the IS off, the camera will jump normally to AI servo mode and keep the subject in focus.

thanx again,
T.O.

[T.O.]

By the way,

I'm sure that I am missing something here, I just can't figure out what it is. When back home this afternoon I will try again and again...maybe there is something I don't understand with the AI focus...

:(
T.O.

[defordphoto]

Personally, I'd avoid using AI Focus. Try just AI Servo and shooting a subject that is definitely moving. AI Servo will kinda get confused if you're trying to shoot a stationary object. I think that maybe that's what you're running into.

Send some photo samples.

[T.O.]

Thank you again RFM Sports,

it's impressive how patient you people are!

I agree with you, AI servo is more than enough for moving objects...it was all about understanding how the Artificial Intelligence of the AI focus works, and if the IS can somehow affect it...

I will read and shoot more over the weekend and hopefully come back with some samples and a clear idea of the whole thing...

all best,
T.O.

[CyberDyneSystems]

AI Focus.. forget it..

Set your camera to AI servo and set custom function #4 to "1" and don't look back ;)

[Outdoor23]

i sure hope both will work independently off each other and still work great together...otherwise...it sure gonna make you work harder for you pictures