DA* AF problem - diagnostic opinions welcome

Charles Robinson charlesr at visi.com
Tue Oct 27 15:02:08 EDT 2009

On Oct 26, 2009, at 20:48, Stan Halpin wrote:
> 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.

Sounds like the focus pin/screw drive is engaging... which it should  
not be doing if you're using it for your jazzy SDM focusing.

I mean - clearly that's what is happening, because flipping the AF/MF  
switch on the body physically retracts that pin from the lens and  
enables you to move things.

I know on my 16-50, if I have the lens off of the camera and rack the  
focus back and forth, that little point where the screw drive would  
engage does not move.  I'm not sure what causes it to grab on and go  
when you have the lens attached to a screw-drive-only body....   (just  
giving you a data point from a camera/lens combination which does work).

> 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.



Charles Robinson - charlesr at visi.com
Minneapolis, MN

More information about the PDML mailing list