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fsdogwood · 10-18-2008, 04:24 PM

Hi there,
I've been doing search on this website, and Google. Try to find some more info.
Got a DA* 50-135mm, found that on my K10D, I could not get focus when the
focal length is set between 90 to 135mm.

I've tried during daytime, with a new battery, switched on lens between MF/AF,
on body AF.S<->AF.C, ... It didn't help.

What could this problem be? Guess I should take it back.

bentax · 10-18-2008, 07:37 PM

is your firmware updated to 1.3?

fsdogwood · 10-19-2008, 02:04 PM

The firmware, I double checked, is at 1.3 level.
Thanks

Damn Brit · 10-19-2008, 02:07 PM

What are the other settings on the camera, if you have a small aperture, it might have problems focusing. Just plain old low light could be a cause as well.

Sean Nelson · 10-19-2008, 03:10 PM

Originally posted by Damn Brit

if you have a small aperture, it might have problems focusing.

AF works with the lens wide open so it shouldn't make any difference what aperture will be used for the exposure.

Sean Nelson · 10-19-2008, 03:12 PM

Originally posted by fsdogwood

I could not get focus when the
focal length is set between 90 to 135mm.

Any issues with other lenses? Is this just an AF problem or do you get blurry pictures even when you manually focus the lens? Is it a sudden change in behaviour from 90mm to 89mm or is it gradual, only becoming noticeable around that focal length?

Igilligan · 10-19-2008, 03:14 PM

do you mean it is not locking focus in that range or that the pics are blurry with a locked on AF?

fsdogwood · 10-20-2008, 08:11 AM

Originally posted by Igilligan

do you mean it is not locking focus in that range or that the pics are blurry with a locked on AF?

Thanks for all the responses, I am returning this copy.

The symptom is, when focal length is set between 90 to 135mm, even at the
maximal 2.8, I could not get the focus locked (the focusing light flashes, and in
AF.S, I could not click the shutter). If I move the focal length to < 90mm, the
lens focuses fine.
In the 90 to 135mm range, the lens tries to get focused by moving back and
forth for several times, and finally would give up, with the flashing focus
indicator.

I could focus with a smaller focal length, say 70mm, move up to the 135mm,
in which case, I could keep the focus.
Manual focusing works fine.

This affects my confidence in the Pentax SDM, with the other post on DPReview,
about the 16-50 failure .

Sean Nelson · 10-20-2008, 10:16 AM

That's a very peculiar failure mode. Best of luck with the repair...

10-18-2008, 04:24 PM	#1
fsdogwood Forum Member Join Date: Oct 2007 Location: RTP, North Carolina Posts: 64	*DA 50-135 won't focus on K10D beyond 90mm** Hi there, I've been doing search on this website, and Google. Try to find some more info. Got a DA* 50-135mm, found that on my K10D, I could not get focus when the focal length is set between 90 to 135mm. I've tried during daytime, with a new battery, switched on lens between MF/AF, on body AF.S<->AF.C, ... It didn't help. What could this problem be? Guess I should take it back.

10-20-2008, 08:11 AM	#8
fsdogwood Forum Member Join Date: Oct 2007 Location: RTP, North Carolina Posts: 64 Original Poster	thanks for the responses Originally posted by Igilligan do you mean it is not locking focus in that range or that the pics are blurry with a locked on AF? Thanks for all the responses, I am returning this copy. The symptom is, when focal length is set between 90 to 135mm, even at the maximal 2.8, I could not get the focus locked (the focusing light flashes, and in AF.S, I could not click the shutter). If I move the focal length to < 90mm, the lens focuses fine. In the 90 to 135mm range, the lens tries to get focused by moving back and forth for several times, and finally would give up, with the flashing focus indicator. I could focus with a smaller focal length, say 70mm, move up to the 135mm, in which case, I could keep the focus. Manual focusing works fine. This affects my confidence in the Pentax SDM, with the other post on DPReview, about the 16-50 failure .

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10-18-2008, 07:37 PM	#2
bentax Senior Member Join Date: Jan 2008 Location: West Australia Posts: 190	is your firmware updated to 1.3?

10-19-2008, 02:04 PM	#3
fsdogwood Forum Member Join Date: Oct 2007 Location: RTP, North Carolina Posts: 64 Original Poster	The firmware, I double checked, is at 1.3 level. Thanks

10-19-2008, 02:07 PM	#4
Damn Brit Guest	What are the other settings on the camera, if you have a small aperture, it might have problems focusing. Just plain old low light could be a cause as well.

10-19-2008, 03:10 PM	#5
Sean Nelson Veteran Member Join Date: Sep 2008 Location: Vancouver BC Canada Posts: 353	Originally posted by Damn Brit if you have a small aperture, it might have problems focusing. AF works with the lens wide open so it shouldn't make any difference what aperture will be used for the exposure.

10-19-2008, 03:12 PM	#6
Sean Nelson Veteran Member Join Date: Sep 2008 Location: Vancouver BC Canada Posts: 353	Originally posted by fsdogwood I could not get focus when the focal length is set between 90 to 135mm. Any issues with other lenses? Is this just an AF problem or do you get blurry pictures even when you manually focus the lens? Is it a sudden change in behaviour from 90mm to 89mm or is it gradual, only becoming noticeable around that focal length?

10-19-2008, 03:14 PM	#7
Igilligan Guest	do you mean it is not locking focus in that range or that the pics are blurry with a locked on AF?

10-20-2008, 10:16 AM	#9
Sean Nelson Veteran Member Join Date: Sep 2008 Location: Vancouver BC Canada Posts: 353	That's a very peculiar failure mode. Best of luck with the repair...

DA* 50-135 won't focus on K10D beyond 90mm

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