DA* AF problem - diagnostic opinions welcome

Stan Halpin stan at stans-photography.info
Tue Oct 27 23:29:15 EDT 2009

Bah - 2nd time today I hit the wrong button. So there we were in the  
monthly VTC with the Boss. My turn. I hit the HangUp button rather  
than the UnMute button.  Bah.
Anyway, as I meant to say in my previous blank message, thanks Leon. I  
am afraid you are right about the camera-lens interaction being the  
possible cause of the problem. One difference between the two bodies  
is that the one where I have the problem has the Battery Grip  
attached, the other doesn't. Will try it all again without grip before  
I send anything away.
And thanks for the K-7 thought. But next on my list is the 60-250.  
Once I recover from that, I may consider the K-7.


> On Oct 27, 2009, at 6:22 AM, Leon Altoff wrote:
>> Hi Stan,
>> It could very easily be a problem with your K20...
>> the camera and lens need to go in together for service...
>> Look upon it as an excuse to get a K7 while the 20D is in for the  
>> service :)
>> Leon
>> 2009/10/27 Stan Halpin <stan at stans-photography.info>:
>>> The lens in question: DA* 300/4.
>>> Basic symptom - it does not autofocus on my K20.
>>> Expanded description - sometimes it works when first turned on,  
>>> but then
>>> refuses to work when woken up after a Sleep period.
>>> "Doesn't work" = nothing happens. It is not mis-focusing, it is  
>>> rather doing
>>> nothing - no response to shutter depression or AF button.
>>> Expanded description of "doesn't work" = not only will it not  
>>> autofocus, but
>>> I cannot manually focus either. Focus rings turns but nothing  
>>> changes.
>>> I tried another DA* lens (50-135) and it works flawlessly.
>>> OK, simple issue, right? Lens needs repair.
>>> So, when it isn't working,  I switch the lens, on the lens barrel,  
>>> to MF. I
>>> still cannot focus!
>>> So, I also switch the AF/MF switch on the body to MF, and then I  
>>> regain
>>> (manual) control.
>>> All pretty definitive so far, it seems that it must be a lens  
>>> problem, and
>>> off to Pentax with it.
>>> But when I use the same lens on a second K20, no problem. It works  
>>> as it is
>>> supposed to.
>>> Dirty contacts on the lens and/or first body? I cleaned those; no  
>>> change in
>>> the lens (mis)behavior.
>>> Any suggestions as to what is going on?
>>> stan

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