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07-01-2009, 12:08 PM   #1
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Focusing problem

I havent had this problem before so dont know if this has to do with my new lens (Pentax 55-300), the K20, me, or any or all of these combo's.

I was taking photo's of some birds sitting in the branches that stick out from the side of a mountain. When I was reviewing them in the monitor(and magnifying them) the birds were blurry but the leaves surrounding them were clear,despite the fact the leaves were right next to the birds. This has happened to me several times The birds,obviously are my main focus.
When looking thru the viewfinder the AF points were all lighting red on the bird(s) and the leaves so why would the birds be out of focus when magnified and not the leaves?

When using my kit lens I never had this happen. Granted the K20(have only had a few months) is a BIG learning curve for me and the lens I've only had about 4 weeks so I'm betting it's something I'm doing wrong.

07-01-2009, 12:15 PM   #2
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It would be helpful if you could post one of the pictures.
07-01-2009, 12:18 PM   #3
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The camera has no way of knowing you'd have preferred the birds to be in focus - it's just looking for something easy to focus on. Even if you tell the camera which focus point to use (I always use the center one) and the red light appears to be on the bird, the actual AF snesor is much larger than the red dot, and indeed, it is quite common for it to choose something else "near" the dot.

The situation you are describing is proabbly the hardest to deal with using AF; you'll probably want to switch to MF for shots like that.

As for why you never had it hppen with the it lens, most likely, you weren't shooting birds in trees with it, or other similar situations where there is just too much "stuff" near your subject to be sure the AF system will focus on the specific thing you wanted it to.
07-01-2009, 02:08 PM   #4
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Shortly after having my first problem shooting a bird in a tree I switched to Spot (Center) Focus. I want to decide what I want in focus (the object that is dead center), I don't let the camera decide for me. As Marc said, the area used is larger then the red square, but that has not been a problem for me. My K100D has not been in 11 point auto mode for a couple of years.

I suppose if I was more creative I might want something in focus that is off center.


Last edited by LeoTaylor; 07-01-2009 at 02:09 PM. Reason: Fixed typo
07-01-2009, 02:09 PM   #5
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Is it possible you are seeing motion (of the birds) blur, and not a focus issue? What shutter speed were you using?
07-01-2009, 03:28 PM   #6
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I believe the autofocus system prefers close objects over far objects -- at least when you're using multi-point autofocus. It makes the assumption, often but not always true, that the closer object is intended to be your "foreground." It has no way of knowing if you intend otherwise. Hey, it has to choose something, and it's better than making a random selection!

As Marc said, this is really a manual-focus situation, or an autofocus-plus-manual-tweak situation.
07-01-2009, 09:10 PM   #7
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QuoteOriginally posted by Quicksand Quote
I believe the autofocus system prefers close objects over far objects -- at least when you're using multi-point autofocus. It makes the assumption, often but not always true, that the closer object is intended to be your "foreground." It has no way of knowing if you intend otherwise. Hey, it has to choose something, and it's better than making a random selection!

As Marc said, this is really a manual-focus situation, or an autofocus-plus-manual-tweak situation.
Birds in trees guarantee out of focus birds unless you focus manually. I briefly tried out the Sigma 170-500 AF with my MZ-S, and found that I got better results with the old M 400, so I kept it and sold the Sigma. With the Sigma, the loss of contrast with the zoom was bad - everything was soft. I have since heard that the 135-400 is better (the same lens with a different final group), but I am no longer prepared to battle off brand lenses. If Pentax does not make it, and did not make it in the past, I do without. :ugh:
07-01-2009, 10:30 PM   #8
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QuoteQuote:
Birds in trees guarantee out of focus birds unless you focus manually.
I agree there... especially native birds as they are coloured for their surounds

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