DA 21 focussing error K10D

Started Aug 20, 2007 | Discussions thread
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blende8 Senior Member • Posts: 1,494
DA 21 focussing error K10D

I posted this in another thread, but it might be of general interest:

We (German forum) have found recently an error in the DA21 camera focus control using the K10D.

Let me explain:
The DA21 focusses differently depending on the aperture set.
There are two settings:

  • focus from f3.2 to f5.6

  • focus f6.3 and higher.

Now, one could assume that this is to comensate spherical abberation errors.

But it turns out that the focus for aperture settings above f5.6 is also better for aperture settings below f5.6!


  • Av

  • set f3.2, focus by halfpressing, take photo

  • keep object distance, leave shutter release button

  • set f6.3 or f8, focus by halfpressing, keep halfpressing and return the aperture back to f3.2, take photo.

It appears that the photo taken by the latter method is sharper.

Please report back how your lens behaves.

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'Good hunters are silent and fast: PENTAX SDM'
(from the new K100D Super catalogue)

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