D200 focus issue?

I was out shooting an airshow on a very hot day, and my D200 started having a particularly irritating focus problem.

On continuous focus at full zoom (300mm), it would lose focus on the far away object, and would try to focus at the near end instead. After it could not find focus, it would give up and not try the far end focus anymore. Happened with all the different focus modes I tried (group dynamic focus, center spot focus, etc).

I've tried the camera many times since then, and it still does the same thing. I believe the focus sensors are fine, as the focus is correct when there's something to focus on. However, when the focus is lost (example- far away plane on a empty sky), the camera just focuses close and gives up. I expect that the camera would keep trying focus Near/far/near/far/... until it found something to lock onto again.

Only way to recover is to zoom out, point it at a large object far away, and coax the camera to focus lock on the far away object, then zoom back in.

What I would like to know is if other D200s do the same thing, or did mine suffer some kind of damage in the heat and need repair. I really don't recall having any problems with CF until that day.

Thanks for the help.
BZ

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I don't recall mine doing that, on most lenses. However, on my macro lens (105VR), if I lose focus, and don't have the limiter switch set, it generally tries to focus for extreme closeup and stays lost in that range until I override with manual focus.

It might help to know what lens you were using and if you see the problem on other lenses.

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cricketer 71

You did not mention what AF mode was selected. I have found that for flying aircraft, dynamic area auto-focus and normal frame works for me.

Does the lens have a focus limit switch that might be set to the wrong setting?
Ron

I was using the 70-300mm VR lens, which does not have a limiting switch (that I know of).

BZ
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I tried the AF mode switch on the different settings - didn't seem to make any difference once it lost focus.

I would have expected that it'll keep trying different focus distance (hunting), but it just went to the close focus region and gave up.

BZ

Michael Deeley said:

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cricketer 71
You did not mention what AF mode was selected. I have found that for
flying aircraft, dynamic area auto-focus and normal frame works for
me.

Click to expand...

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I think mine did the same thing at an air show but it was when I lost most of the plane (out of sensor) I found the best was to use center focus and a lot of practice.

Were you using Dynamic-area AF with closest subject priority? Page 54 of manual.

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FINE PRINT: I reserve the right to be wrong. Should you prove me wrong, I reserve the right to change my mind.

Bernard Zee said:

I was out shooting an airshow on a very hot day, and my D200 started
having a particularly irritating focus problem.

Click to expand...

Some airshows offer action that is closer-in than others. In this case, how far away were these jets? When they were in focus, were they positioned beyond the lenses infinity focus point?

If so, maybe consider turning AF off completely for this kind of subject and simply keep the lens focused at infinity.

--
'Here, look at the monkey. Look at the silly monkey!'

Tom Young
http://www.pbase.com/tyoung/

Appreciate all the suggestions on different focus modes which would help to keep from losing focus to begin with. However, I still don't know if my camera is behaving normally or has a problem when it does lose focus.

The thing that kills me is, when the focus is lost, and the camera moves the focus all the way to the closes point, half pressing the shutter will often do nothing! It is as if the camera believes that the subject is closer than the closest it can focus, and so doesn't even try.

The only workaround I see is to manully move the focus ring towards infinity and try again. Just doesn't seem right.

With regard to using focus at infinity, I don't think that would yield the sharpest pics. Ranges of the subject are from 200 yards on out.

Thanks,
BZ

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Hi BZ!
I've experienced exactly the same symptom with the 70-300VR and the 105VR.

The camera loses focus and moves tho the closest distance and never starts again.

Only way to recover from the situation is to focus manually.

But it seems that nobody else is suffering from this.

BR -- cfmi59

I've experienced it too, with a 70-300VR (and a Sigma 70-300) on the D200. I always assumed it was due to the fact that it's a relatively slow lens?

cfmi59 said:

Hi BZ!
I've experienced exactly the same symptom with the 70-300VR and the
105VR.
The camera loses focus and moves tho the closest distance and never
starts again.

Only way to recover from the situation is to focus manually.

But it seems that nobody else is suffering from this.

BR -- cfmi59

Click to expand...

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http://www.pixelfixer.org

After installing the new D200 firmware (2.01), the focus problem no longer occurs with the 70-300mm VR lens!

Makes me much happier!

BZ
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