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10-21-2010, 09:11 PM   #1
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k-7 auto focus problems

I rarely use the k-7 but i was in very good light and wanted to try to use it for birds in flight.
I took a sigma 300mm f2.8 lens and set it up. It would start to focus then just lock up. I tried it for about 30 minutes. every time the same results. In contunious focus it would lock up every time.
I put it on the k-x and no problems. What is the problem with the k-7. Another thing i am seeing on the k-7 is out of focus shots. The motor is much quicker than the k-x but much less accurate focus?
I put the kit lens back on the k-7 and no porblem. The k-7 is a constant disapointment to me.
I am rather scared to upgrade to the k-5.

10-21-2010, 10:02 PM   #2
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By Lock Up, do you mean it just gives up trying to focus? Or that the focus mechanism actually Locks up and won't turn anymore? I've never really cared for the AF-C on any of my cameras, subjects are usually moving faster than the camera can track (in my hands) or I'm doing something wrong. In all my attempts, I've managed only once to catch a Bird in Flight..

I am certain this was done with a focus trap (catch in focus) by turning off the SDM on my DA*300. Autofocus, no way. I'm sure it's a skill thing or lack thereof in my case though.

10-21-2010, 10:09 PM   #3
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It's like the motor stalls. It hums a few times then gives up. But my k-x works fine. And the k-7 works with the kit lens on continus af...
10-21-2010, 10:42 PM   #4
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It seems that the AF has some difficulty to "catch" your target.

I suggest that you set first:
- AF-S
- Center-focus

In that mode, you need to have the bird in the centrer of your screen for AF confirmation. Yet it is not easy to focus on a flying bird moving away (or towards you) fast. I have a similar problem with my DA18-250mm at 250mm.

(THe AF-C mode does not need AF confirmation to shoot and your photos might be out of focus.)

However, with a faster moving object, AF is not simple and you might consider MF. At a recent school fair, I use my MF Voigtlander 58mm to shoot the children and I was quite successful.

Food for thoughts...

10-21-2010, 11:11 PM   #5
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The K7 is capable of capturing birds in flight. I have done so on numerous occasions, but it takes practice. I agree with the suggestion to set your camera to AF-S and center-focus. If you know someone who also has a K7 you may want to try the lens (Sigma) on it to see if the problem is consistent on a K7, or whether your camera might need repair. There are several threads that talk about focus issues and the K7. If you do a search you will find them. Blur can be do to several different factors such as whether and how the shake reduction feature is being used or the shutter speed used with moving objects. Many lenses at 2.8 have a problem with the image being a bit soft (not real sharp) and this can be mistaken for blur produced by the camera. The K7 has the ability to be fine tuned to the focus characteristics of different lenses. I haven't made use of this feature, but there are threads explaining how it works here on the forum.
10-21-2010, 11:50 PM   #6
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(THe AF-C mode does not need AF confirmation to shoot and your photos might be out of focus.)

I did not know that. Good to know.
I am headed back tomorrow. I will check it again.

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