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04-07-2019, 05:55 PM   #16
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QuoteOriginally posted by amstel78 Quote
Could it have been possible that most keepers taken with your K10D were shot using a smaller aperture?
No. I bought the FA 43 right after buying the K10D and used it at f/1.9 occasionally and f/2-2.2 often for portraits, stock, and product photography. Something changed, and my camera has never been dropped and has been taken care of.

What I'm not sure of is how common something like this is with the K10D, especially where it worked perfectly before and has worked perfectly since the adjustment.

04-07-2019, 06:02 PM   #17
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QuoteOriginally posted by builttospill Quote
No. I bought the FA 43 right after buying the K10D and used it at f/1.9 occasionally and f/2-2.2 often for portraits, stock, and product photography. Something changed, and my camera has never been dropped and has been taken care of.

What I'm not sure of is how common something like this is with the K10D, especially where it worked perfectly before and has worked perfectly since the adjustment.
Interesting. Could it be the SR mechanism. Who knows?

I always thought my K10D was spot on right out of the box. I bought mine early in 2008 as a demo unit but it turned out to be BNIB old stock. It had 0 shutter actuations. I used it sparingly, and just like yours, has never been dropped or ill treated. Only when I took home the 35mm f2 a few days ago did I notice a backfocus issue. Swapping lenses back to the 18-135 did I notice the same problem exhibiting itself at 18mm f/3.5. Fortunately, correcting to +130um solved the problem for both lenses.

I still found it odd that I've never noticed this issue before. Going back over old photos, I see some OOF shots at wide apertures, but others are fine. Go figure.

Edit: meant to say I bought my K10 in 2018, not 2008.

Last edited by amstel78; 04-07-2019 at 06:21 PM.
04-08-2019, 09:55 AM   #18
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I had forgotten that there is an objective review of the FA 35/2 on the K10D that included Imatest results...

From Pentax SMC-FA 35mm f/2 AL - Review / Test Report - Analysis

Steve
04-08-2019, 05:50 PM   #19
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QuoteOriginally posted by builttospill Quote
I too bought my K10D in 2007. I still use it occasionally at ISO 100. I've always hated the idea of having to make adjustments for a lens to be sharp, so I buy premium lenses, and to this day have never had to make an adjustment for a lens. Honestly I'd be disappointed if I paid a premium price for a premium lens and it wasn't ready to go. That's why I bought the higher-end lens. It would be different for a cheap lens.

Several years into owning the K10D I went to a scheduled shoot and all photos I took of the model were out of focus, just slightly. This had never happened to me before, and after additional testing, every photo was showing just a little back-focus. Something had changed. The camera's focus had always been spot-on before this. I thought it may be due to the original sensor-shift mechanism, as the K10D was the first to have this. I never verified this, and don't have a way to do so.

I used debug mode to adjust the overall focus in my K10D. This was the only time I have had to make an adjustment. Focus has been exact since, and the adjustment was made around eight years ago.
My K10D experienced exactly the same as yours. I had no idea why it all the sudden back focused. Then, after I adjusted +110 it focuses spot on again, for all lenses.

04-08-2019, 08:18 PM   #20
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Isn't the K10D the body that has mirror sagging issues that develops over time? And wouldn't that mess up auto focus accuracy?
04-08-2019, 10:59 PM   #21
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QuoteOriginally posted by stillshot2 Quote
Isn't the K10D the body that has mirror sagging issues that develops over time? And wouldn't that mess up auto focus accuracy?
There were theories about such, but I don't remember whether there was hard evidence. The thought was that since the K10D and other bodies had a single rest post for end of travel, that the unsupported side would sag lower over time and throw off the light path to the PDAF sensor. Such would also seriously compromise manual focus.

Addendum: The other half of the mirror sag story was that something like that might have been responsible for reports of tilted photos. Even with the camera viewfinder frame well aligned to walls or horizon, photos taken would not be true to those lines. At least some of those cases were due to misalignment or poor seating of the focus screen frame or the screen itself. Others required service visits for sensor or viewfinder alignment. Again, I don't know that any sag was ever confirmed.


Steve

Last edited by stevebrot; 04-08-2019 at 11:37 PM.
04-08-2019, 11:14 PM   #22
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QuoteOriginally posted by stevebrot Quote
Interesting...I bought K10D new in 2007, shortly before joining Pentax Forums and don't remember any buzz about pervasive backfocus issues
QuoteOriginally posted by amstel78 Quote
It's possible Steve; perhaps I just got a bad one out of the box and never realized it until now.

But, Google searches do turn up quite a few results on backfocus issues with the K10D.
I did a bit of research on this and even found some threads on this site involving user complaints that I was a part of. That bumped my memory. There were several users on this site with persistent issues of back/front focusing and poor focus in general. Often it was with a particular lens with the problem resolving after a trip of lens and camera to the service center to have them pair matched. In retrospect, it is likely that centering defect was to blame in some cases and who knows what in others. A common experience was complete remission after a service visit for cleaning. Back in those times (2007 - 2010), the knowledge pool was pretty shallow with few participants on this site (myself included) having working knowledge of PDAF, its weak points, and why it might misbehave.

Over time, instructions to access the debug service menu came to light that provided a means for global AF fine adjust. With the means to tweak at hand, most of the discussion on the matter evaporated.


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04-09-2019, 03:17 AM   #23
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QuoteOriginally posted by stevebrot Quote
Over time, instructions to access the debug service menu came to light that provided a means for global AF fine adjust. With the means to tweak at hand, most of the discussion on the matter evaporated.
Yes, I'm glad to have found instructions on how to enter the debug menu and that it was still accessible using the CF card and text file trick under firmware 1.31. My sample required +130um in order to correct backfocus. Now the 18-135WR and 35 f2 wide open produce focused images consistently.

04-09-2019, 05:40 AM   #24
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I always had backfocus issues with my K10D and it was my first camera ever and I was a newbie, didn't even know such thing existed. I was incredibly disappointed by the results I was seeing and it only made me think other brands are better since Pentax's images are so blurry :/ I could have taken so many good images with the K10D, had I known there could be adjustments done to the focus.
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