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03-04-2009, 11:15 AM   #1
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k10D focus adjust

Hi,

I just got a new 28mm 2.8 lens that backfocuses--obviously and painfully (Thirty bucks if anyone's interested in buying it--oh yeah, and it flares unless the light source is just about over my shoulder. Oh, and the purple fringing is absolutely beautiful, almost heavenly--it's a CPC Phase 2, made by Cosmicar. Cosmicar--how can you resist?).

Anyway, this lens prompted me to put my camera on a tripod, and run some tests. I found that the camera slightly backfocuses on all my lenses. My question is this: if I run the debug program and adjust the focus, will it affect my split-screen focus? Right now, the autofocus indicator and the prism split are right on with each other--both slightly behind (or would that be in front of?) the target.

I'm most interested in having the split prism accurate, since my faster lenses are mostly going to be manual focus primes. But I would love it if they were both on.

Thanks for any knowledge on this,
Vinny

03-04-2009, 11:46 AM   #2
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There are three methods of correcting backfocus in the K10. There is a do-it-yourself software fix, a mechanical fix involving taking off the baseplate and adjusting screws and probably the safest option of sending the camera in to Pentax for adjustment. It is best to send camera and lenses as I think Pentax can set it for more than one lens. The DIY methods produce a global adjustment which affect all lenses used.
The easiest solution is to upgrade to a K20D which allows adjustment for multiple lenses - anexpensive solution!
Archie
03-05-2009, 02:10 PM   #3
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Helios, thanks. What I'm most curious about, is which of these solutions (if any) affect both the split prism screen and the autofocus mark. I guess I'll learn by doing. I'm going to tackle it tonight or tomorrow.
03-05-2009, 08:22 PM   #4
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baseplate fix?

QuoteOriginally posted by helios Quote
a mechanical fix involving taking off the baseplate and adjusting screws
hey, that's one i haven't heard of! do you have a link or other info for that proceedure?

on my k10d, i was having BF problems for 6 months or so before i discovered it wasn't my fault. mine took two different fixes: for the lens, i used the downgrade/debug software to get the lens to AF correctly, but my manual focus was still off. after getting a katseye and finding it was STILL off, i had to place paper shims under my focusing screen to fix that. now it's very close, but not yet spot on. so if you have a link to that base-plate fix, i'd love to see it. thanks!

kauaiguy

03-05-2009, 09:02 PM   #5
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In answer to my own question, no the debug does not do anything physical, does not change the point of focus on the split screen.

So now I'm in the same boat as kauaiguy. Now that my auto focus is on, my split screen is off, and I'm going to have to shim and hope I can get it back in line with the autofocus.
03-07-2009, 09:43 AM   #6
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QuoteOriginally posted by kauaiguy Quote
hey, that's one i haven't heard of! do you have a link or other info for that proceedure?

on my k10d, i was having BF problems for 6 months or so before i discovered it wasn't my fault. mine took two different fixes: for the lens, i used the downgrade/debug software to get the lens to AF correctly, but my manual focus was still off. after getting a katseye and finding it was STILL off, i had to place paper shims under my focusing screen to fix that. now it's very close, but not yet spot on. so if you have a link to that base-plate fix, i'd love to see it. thanks!

kauaiguy
There has been quite a lot of discussion of adjustment of auto focus by making a mechanical adjustment to the screws under the base plate. If you do it it could invalidate your warranty so it is very much at your own risk! Here is a link from which you could find others:-
I have fixed my front focus problem - how to: Pentax SLR Talk Forum: Digital Photography Review

I hope this helps.

Archie
03-07-2009, 12:57 PM   #7
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thanks, Archie, for that link. your comment on invalidating the warranty is certainly good for others thinking of this fix. in my case, is k10d is fairly ancient though lovingly used, so it's way out of warranty and i still probably won't do it, since the reversion/debug software fix worked fine months ago... but the baseplate fix info is certainly going into my bookmarks. many thanks!

kauaiguy
08-10-2009, 05:11 AM   #8
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Thanks guys for great posts. I have this same problem with a few lenses and I tend to change lenses quite often. So I don't know if I should attempt to adjust my k10d because if it's good for 1 lens, others will be out of focus ... sound like I need a K20D or K-7

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