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Author Topic: AI Focus tracking issue, or user error?  (Read 2331 times)

EOBeav

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AI Focus tracking issue, or user error?
« on: October 26, 2012, 09:32:34 PM »
I shot this with a 5DmkII and a 70-200mm f/4 L, AF AI Servo mode. As you can tell, the image is focused just behind the runner, yet I had the focal point zeroed in on the runner's chest the entire time. Otherwise, the lens autofocuses really well. Is it me, or my gear? Should I plan on focusing just in front of the runner to compensate for AF lag?

Granted, my body/lens combo is suited more for landscapes than it is high school football. The easy answer here is to say "get a 70-200mm f/2.8 L IS", but that ain't gonna happen any time soon.

Thanks in advance for your thoughts. EXIF data is listed just below the image. See the largest file size for more detail if you need to.


Touchdown! by Rick.Scheibner, on Flickr

EXIF:
Exposure   0.001 sec (1/800)
Aperture   f/4.0
Focal Length   200 mm
ISO Speed   500
Exposure Bias   0 EV
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AI Focus tracking issue, or user error?
« on: October 26, 2012, 09:32:34 PM »

PackLight

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Re: AI Focus tracking issue, or user error?
« Reply #1 on: October 26, 2012, 09:49:28 PM »
Really not a good example, if it is back focused it is not by much.
The 5D II is not the most precise accurate AF system in AI servo.
You should be using center point with surrounding assist points. It has been a while since I used my 5D in AI so it may be called something else.
Examples like this is why I switched to a 7D and later to a 1D IV.

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Re: AI Focus tracking issue, or user error?
« Reply #2 on: October 26, 2012, 09:57:30 PM »
Focusing on a runner coming toward you is challenging for any camera, and a 5D MK II is going to be weak in that application.  This is where a 7D or better yet, a 5D MK III will be noticibly better.

EOBeav

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Re: AI Focus tracking issue, or user error?
« Reply #3 on: October 26, 2012, 10:10:27 PM »
Focusing on a runner coming toward you is challenging for any camera, and a 5D MK II is going to be weak in that application.  This is where a 7D or better yet, a 5D MK III will be noticibly better.

So it's the body and not the lens? I was hoping your response would justify getting a 135mm f/2 for basketball season. :-)
In landscape photography, when you shoot is more important than where.

Gear: Canon 5DmkII, 17-40mm f/4 L, 50mm f/1.4, 70-200mm f/4.

PackLight

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Re: AI Focus tracking issue, or user error?
« Reply #4 on: October 26, 2012, 10:16:04 PM »
Focusing on a runner coming toward you is challenging for any camera, and a 5D MK II is going to be weak in that application.  This is where a 7D or better yet, a 5D MK III will be noticibly better.

So it's the body and not the lens? I was hoping your response would justify getting a 135mm f/2 for basketball season. :-)

Well of course  both a lens and new body would help  :P

neuroanatomist

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Re: AI Focus tracking issue, or user error?
« Reply #5 on: October 26, 2012, 10:23:08 PM »
So it's the body and not the lens? I was hoping your response would justify getting a 135mm f/2 for basketball season. :-)

Sorry to disappoint.  :P  My 5DII in AI Servo had trouble keeping up with my 3-4 year old daughter running towards me, let alone a football player.  My 7D could do it, even with a lens as slow-focusing as the 85L II. 
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EOBeav

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Re: AI Focus tracking issue, or user error?
« Reply #6 on: October 26, 2012, 11:19:24 PM »
Sorry to disappoint.  :P  My 5DII in AI Servo had trouble keeping up with my 3-4 year old daughter running towards me, let alone a football player.  My 7D could do it, even with a lens as slow-focusing as the 85L II.

I was just about to get the 7D last winter when I saw that the 5DmkII took a price dip. I went that route instead, and couldn't be happier. It's been great for landscapes and the few portraits that I do. Really getting into sports photography would require some additional investment that I'm not really willing to make right now, so I'll just need to make due with what I've got. I'll still hold out for that 135mm f/2 for basketball season, though.
In landscape photography, when you shoot is more important than where.

Gear: Canon 5DmkII, 17-40mm f/4 L, 50mm f/1.4, 70-200mm f/4.

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Re: AI Focus tracking issue, or user error?
« Reply #6 on: October 26, 2012, 11:19:24 PM »

Menace

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Re: AI Focus tracking issue, or user error?
« Reply #7 on: October 26, 2012, 11:24:27 PM »
I'd suggest a 7d too - you can still marry it the 135 f2  ;)
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Re: AI Focus tracking issue, or user error?
« Reply #8 on: October 26, 2012, 11:37:05 PM »
So it's the body and not the lens? I was hoping your response would justify getting a 135mm f/2 for basketball season. :-)

Sorry to disappoint.  :P  My 5DII in AI Servo had trouble keeping up with my 3-4 year old daughter running towards me, let alone a football player.  My 7D could do it, even with a lens as slow-focusing as the 85L II.

+1.  Turn on the assist focal points, but I don't really see much of an improvement with them activated.  Use the longest focal length you can -- distance is your friend.  Take bursts.  If the subject is close and moving toward the camera, expect to throw most of the shots away.

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Re: AI Focus tracking issue, or user error?
« Reply #9 on: October 27, 2012, 12:01:44 AM »
Guess it is your shadow in the picture? At this distance the internal lenses have to shift a big distance to change focus. And you want that to happen in nil time? Can not call it user error. More too high user expectations. More distance, longer lens, will solve the problem. (Also much saver.)

neuroanatomist

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Re: AI Focus tracking issue, or user error?
« Reply #10 on: October 27, 2012, 12:33:58 AM »
Guess it is your shadow in the picture?

Focal length is 200mm. To frame a 6' person means 35-40' away, assuming no further cropping. If that's his shadow in the picture, he's well over 20' tall...
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EOBeav

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Re: AI Focus tracking issue, or user error?
« Reply #11 on: October 27, 2012, 01:19:44 AM »
Focal length is 200mm. To frame a 6' person means 35-40' away, assuming no further cropping. If that's his shadow in the picture, he's well over 20' tall...

Actually, it is my shadow. The sun was very low on the horizon, as you could also tell by the very warm tones and other long shadows from the players. I was standing just behind the end zone, and he was crossing the goal line when this photo was taken.
In landscape photography, when you shoot is more important than where.

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neuroanatomist

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Re: AI Focus tracking issue, or user error?
« Reply #12 on: October 27, 2012, 06:22:02 AM »
So....I take it you're not 20' tall??   :-[
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Re: AI Focus tracking issue, or user error?
« Reply #12 on: October 27, 2012, 06:22:02 AM »

Kernuak

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Re: AI Focus tracking issue, or user error?
« Reply #13 on: October 27, 2012, 07:39:04 AM »
Focusing on a runner coming toward you is challenging for any camera, and a 5D MK II is going to be weak in that application.  This is where a 7D or better yet, a 5D MK III will be noticibly better.

So it's the body and not the lens? I was hoping your response would justify getting a 135mm f/2 for basketball season. :-)
There are other justfications for the 135 f/2. The wider aperture will be better for indoor sports and it also makes a useful landscape lens for longer viewpoints (although you do already have a 70-200). Also, if you're tracking sideways, the 5D MkII will cope better, as the focal distance won't change so quickly.
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EOBeav

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Re: AI Focus tracking issue, or user error?
« Reply #14 on: October 27, 2012, 10:52:32 AM »
So....I take it you're not 20' tall??   :-[
Ha...not quite, 6' 4".
In landscape photography, when you shoot is more important than where.

Gear: Canon 5DmkII, 17-40mm f/4 L, 50mm f/1.4, 70-200mm f/4.

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Re: AI Focus tracking issue, or user error?
« Reply #14 on: October 27, 2012, 10:52:32 AM »