EOS 1D Mk3: AI Servo and IS

[AlexShark]

Here's a problem that drives me nuts. I don't get great focussing results with the following settings:

1. High burst (10fps)

2. AI Servo AF

3. Center point AF

4. IS type 1 on 100-400L

Anyone knows what's the deal? Can AI and IS conflict? (The serial # on the camera is out of the "defective" AF range.)

[DrJalapeno]

Perhaps your question can be answered here. Alex.

[Lazy_Eye]

Are you new to this type of high performance camera? There are some things to be aware of.

First of all, you're using typical AF settings for tracking autofocus. The technique is to lock the center AF on the object you wish to track and start firing when ready. The camera is set up so that it will fire regardless of AF lock or not, and you will find that some images are not in focus because the AF is transitioning to the predicted focus point. The other factor is the IS. When the IS array reaches it's physical limits, it will "reset" and begin tracking again, and when this happens, the image lurches and can cause a blur that looks like misfocusing. This tends to happen more in mode one because the system is tracking both vertical and horizontal motions. When panning in mode 2, the horizontal tracking is turned off and if you have good panning technique, the IS will rarely reset in the vertical direction.

I own a 1D-II and expect a certain percentage of the images to be out of focus for the above reasons. I do get a much higher yield of sharp images when shooting with a non-IS lens from a tripod, leading me to believe that the main cause is the IS system and not the AF performance.

Message Edited by Lazy_Eye on 12-22-2007 08:35 AM

[AlexShark]

John, thanks for the link. I am using the camera that according to CanonUSA.com should not have the problem, and I am using firware 1.1.3 -- it's already downloadable. And the ambient temperature was around 60.

Lazy_Eye -- this is my first! I don't even know all of the controls yet, and frankly, I'm scared to touch the beast! I guess I'll just have to test the 4 possibilities: no AI, no IS - AI, no IS - no AI, IS - AI, IS. And see what works best. Actually, what puzzles me is performance of AI in 10-burst mode: any real tracking is done before the first photo is taken, there's just no way to track thereafter, physically. So do I need it at all under the circumstances?

Interestingly, I do recall now that sometimes my 20D would give a poor shot in a burst of 3-4. It was also set to AI servo. Checked some of the sequences and it really is there -- the second frame has a greater chance of being focussed.

Message Edited by AlexShark on 12-22-2007 11:42 AM

[Lazy_Eye]

Hi Alex, and congrats on getting what I consider to be one of the best series of pro cameras ever made!

In servo mode, the camera will continue to track focus while you're shooting a sequence of shots. You can set a lower frame rate with JPEG only and shoot pretty much continuously until the card fills with the Mark III, and it will continue to track focus on as long as it can detect the subject. Sometimes, though, it can unlock and hunt, or simply not focus fast enough to stay locked on some fast moving objects. I shoot a lot of motorsports-type subjects and I'm often shooting hand held at long zoom settings, and I see both the AF and IS errors fairly often, especially in marginal conditions where contrast is fairly low. This is really no different than the AF operation when I shot pro film cameras like the Nikon F5 and F4s, except the AF performance on these Canon cameras with ring USM and newer electronics is much better than the F5 and F4s ever hoped to be.

[AlexShark]

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Lazy_Eye wrote:

Hi Alex, and congrats on getting what I consider to be one of the best series of pro cameras ever made!

In servo mode, the camera will continue to track focus while you're shooting a sequence of shots. You can set a lower frame rate with JPEG ...

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Thanks!

The suggestion would defy the very purpose of getting this miracle of engineering.

Digging through some Custom Function I came across some extra settings for AF, that fine-tune AI. Maybe it will help.

But it doesn't remove my concern that:

1. AF tracking and IS tracking may well be undermining each other and one should be careful using them together.

2. AF might be lousy at 10 fps simply because the human behind the camera is tracking blind! There's just no way I can accomplish that -- the viewfinder is essentially closed throughout the burst.

[Lazy_Eye]

Get used to keeping your other eye open while you shoot. That helps you keep the camera tracking smoothly.

[AlexShark]

There's something in the camera manual about it.

C. Fn. III-6, setting 5:

IS start. When lens' IS is on, it operates when you press the button. (I assume, this is the AF-ON button on the camera.)

Something to try. I'll just need an extra finger on the trigger, but if this means what I think it does, I can safely track, and then activate IS together with the shutter.