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06-02-2010, 12:56 PM   #1
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AF.C problems

I shoot with the K20D. When trying to capture running dogs in focus, especially when they are running towards me, I am having problems with getting a sharp in focus pic.
My shutter is fast enough, I have it set on center focus, and AF.C with varying aperture. I am using the DA* 50-135mm f2.8 lens.
Is it possible that the camera is just too slow to focus on such a fast moving object? Should I be stopping down the aperture to gain better depth of field increasing my chance of getting the dogs face in focus? Any advice would be helpful!!

06-02-2010, 01:12 PM   #2
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Could it be that by the time the camera focus's, and takes the picture, that the dog has already ran out of the focal point since it is coming towards you? What about when they are running from left to right and you pan from one side to the other?
06-02-2010, 01:19 PM   #3
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I've found that Pentax AF just isn't fast enough for capturing my dogs when they are coming at me as well.
Probably if I had a Chihuahua it would be different, but I have a Belgian and a Rottie, both of which are pretty fast animals when they get going.
I actually have better success by focusing where I know they will be and then tripping the shutter just before they get there. One has to develop a feel for this, as there is no formula, there is a lag from the time you decide to push the button to when the shutter opens, and this has to be accounted for.
Stopping down will help a lot, as will working at longer focal lengths with the dogs farther away, since the AF will keep up more easily.
Also, rather than running them right at you, try having them run somewhat off to the side, again, this will let the AF have a better chance of keeping up.
I'll also try to slow them down a bit by running them in shallow water. It makes my job easier, and the images are more dramatic.





A couple of examples to give you an idea of what I mean. Both of these were shot with a manual focus 80-200 zoom on the K20.
06-02-2010, 01:45 PM   #4
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QuoteOriginally posted by SashasMom Quote
I shoot with the K20D. When trying to capture running dogs in focus, especially when they are running towards me, I am having problems with getting a sharp in focus pic.
My shutter is fast enough, I have it set on center focus, and AF.C with varying aperture. I am using the DA* 50-135mm f2.8 lens.
Is it possible that the camera is just too slow to focus on such a fast moving object? Should I be stopping down the aperture to gain better depth of field increasing my chance of getting the dogs face in focus? Any advice would be helpful!!
I've got the same exact setup and have difficulty with motorcycles coming towards me. It is possible that the camera/lens is just too slow for the situation that you describe, unfortunately.

One thing that I haven't tried which may help is setting the DA* 50-135 to severely backfocus. This would artificially move the DOF closer to you and hypothetically increase the chances of an approaching dog being in focus. Never tried it myself though...

06-02-2010, 01:52 PM   #5
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Not the fault of Pentax. For that case, none of camera so far is fast enough to focusing on the quickly moving subjects towards you, including the latest released Canon 7d.
06-02-2010, 04:54 PM   #6
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thanks to all that replied. Just glad to know its a camera problem and not me, I think? I have another friend that shoots with a Nikon D90, she has similar problems. I thought about trying the back focus thing, but think focusing on a point in front of the dog then shooting just before its gets to that point would work better. The back focus would be more inconsistent since dogs run at different speeds.
06-02-2010, 05:48 PM   #7
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QuoteOriginally posted by SashasMom Quote
thanks to all that replied. Just glad to know its a camera problem and not me, I think? I have another friend that shoots with a Nikon D90, she has similar problems. I thought about trying the back focus thing, but think focusing on a point in front of the dog then shooting just before its gets to that point would work better. The back focus would be more inconsistent since dogs run at different speeds.
You could also try Catch-in-Focus. Set the DA* to Manual, keep the K20d in AF.S, and then turn on the Catch-in-Focus custom mode. Hold down the shutter and manually focus. The camera will trip the shutter only when it has detected focus. I'll have to step outside and see if it works...
06-02-2010, 08:16 PM   #8
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QuoteOriginally posted by johnmflores Quote
You could also try Catch-in-Focus. Set the DA* to Manual, keep the K20d in AF.S, and then turn on the Catch-in-Focus custom mode. Hold down the shutter and manually focus. The camera will trip the shutter only when it has detected focus. I'll have to step outside and see if it works...
Don't bother.
It's far too slow.

06-02-2010, 09:53 PM   #9
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A different technique consists in using MF and Hi continuous shooting. Focus the lens in front of the dog/car/object running towards you, and start to shoot a continuous sequence before the dog/car/object enters into the focus zone.

Out of the sequence, you are likely to have a couple of good shots that are well focused. Make sure that the shutter speed to fast enough however.

Hope that the comment will help...
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