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07-01-2008, 04:10 AM   #1
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K10D Hardware focusing screen plane adjust?

Finaly got a katzeye screen, and that allowed me to confirm what I suspected since my k10d buy; the focusing screen plane and sensor plane are not at the same distance from lens flange.
There is a constant backfocus so it means the focusing screen lies farther from the lens flange then the sensor.
AF adjust menu is of no use as I mostly use manual focus lenses (and fast primes on top..). So I need these two distances to be the same.
Does anybody knows of an way to adjust the focusing screen plane?
(I read somewhere the sensor is not adjustable, so this is no option).
Thanks!

07-01-2008, 04:15 AM   #2
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Manufacturing error

I am afraid you have not much can do for this misalignment. Its either the Katzeye is too thin or too thick, or, your camera body is misaligned. First contact Katzeye and then Pentax to see if they could help you.
07-01-2008, 04:59 AM   #3
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Position Error of CCD plane can be adjusted by Engineering Debuging.
Whereas AF sensor position and other optical planes cannot be adjusted easily. (up to present knowledge)

"Focus correction function" can shift the position of the CCD plane to resloved some FF/BF. But the value drift in too much amount could resulted that the AF at "Infinite Position" become invalidated for some lenses and in some cases (for example Kit).

Last edited by ckanthon; 07-01-2008 at 05:06 AM.
07-01-2008, 06:18 AM   #4
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QuoteOriginally posted by ckanthon Quote
Position Error of CCD plane can be adjusted by Engineering Debuging.
Nope. It is FIXED.

QuoteQuote:
Whereas AF sensor position and other optical planes cannot be adjusted easily. (up to present knowledge)
Nope. The AF sensor module "plane" can be adjusted:

RiceHigh's Pentax Blog: Focus Calibrations for (Pentax) (D)SLR Bodies and Lenses

07-01-2008, 07:05 AM   #5
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Thanks for your inputs!

It seems my body is simply misaligned, the katzeye reveals it pretty badly, if only there wouldn't be FF\BF issues with some of my AF lenses as well I would stick with those on the K10D, but not having reliable focus with manual lenses (focusing screen plane too far), nor with AF lenses (except my FA 50mm macro, they all require some different adjustments in debug mode) is really annoying.

By the way any ideas as to why one of my lens (Tokina AF-X Pro 80-200mm f2.8) needs different AF corrections depending on the focus distance?
From around +90 at min. focus (1.8m) to more then +300 at 20m or so..(some slight change depending on the zoom setting as well......)
Kind of makes it unusable........
07-01-2008, 07:09 AM   #6
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QuoteOriginally posted by kelleri Quote
Thanks for your inputs!

It seems my body is simply misaligned, the katzeye reveals it pretty badly, if only there wouldn't be FF\BF issues with some of my AF lenses as well I would stick with those on the K10D, but not having reliable focus with manual lenses (focusing screen plane too far), nor with AF lenses (except my FA 50mm macro, they all require some different adjustments in debug mode) is really annoying.

By the way any ideas as to why one of my lens (Tokina AF-X Pro 80-200mm f2.8) needs different AF corrections depending on the focus distance?
From around +90 at min. focus (1.8m) to more then +300 at 20m or so..(some slight change depending on the zoom setting as well......)
Kind of makes it unusable........
Yes it looks like it should be repaired but one question. There is (I believe) a shim for the focusing screen. Is one present and is it on the right side? As a quick test shift shim to the other side. Second, even w/ MF you can get AF confirmation. Do they coincide?
07-01-2008, 07:22 AM   #7
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No shim here with my katzeye. I think it is the case with an other focusing screen brand, but not the katzeyes.
The AF confirmation works and seem to agree with stigmometer (it is less precise though), using no AF correction, resulting in a nice backfocus. So it could be that it is the sensor that is somehow too close to the lens, but it was my understanding that it is no-adjustable....
07-01-2008, 08:04 AM   #8
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QuoteOriginally posted by RiceHigh Quote
.....

Nope. The AF sensor module "plane" can be adjusted:

RiceHigh's Pentax Blog: Focus Calibrations for (Pentax) (D)SLR Bodies and Lenses
Thanks for your clarification on that: which meant it is the other way round... CCD plane is "fixed" Whereas AF sensor "plane" is adjustable (K10d debuging mode).


Last edited by ckanthon; 07-01-2008 at 08:19 AM.
07-01-2008, 01:53 PM   #9
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I think it highly unlikely that the Katz Eye is the problem but it is not inconceivable that a focusing screen could, by being made intentionally out of spec, compensate for the problem.
07-01-2008, 02:53 PM   #10
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QuoteOriginally posted by Parallax Quote
I think it highly unlikely that the Katz Eye is the problem but it is not inconceivable that a focusing screen could, by being made intentionally out of spec, compensate for the problem.

That's a good idea, actually. The focusing screen is presently to far from the lens, I could in fact use a thin shim to set it further away from the pentaprism = nearer to the lens, just like some focus screen manufacturers do. That could, if I find the right thickness, solve the problem with MF completely!
Has anyone already tried making such a shim for the focusing screen?
07-01-2008, 03:07 PM   #11
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QuoteOriginally posted by kelleri Quote
That's a good idea, actually. The focusing screen is presently to far from the lens, I could in fact use a thin shim to set it further away from the pentaprism = nearer to the lens, just like some focus screen manufacturers do. That could, if I find the right thickness, solve the problem with MF completely!
Has anyone already tried making such a shim for the focusing screen?
W/ some of the Pentax screens had a shim as part of the screen assemby. Is it stuck on the old screen. If it's there the katzeye would need it as well. Just a thought
Also I assume you set the diopter adjustment....
07-01-2008, 03:41 PM   #12
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QuoteOriginally posted by jeffkrol Quote
W/ some of the Pentax screens had a shim as part of the screen assemby. Is it stuck on the old screen. If it's there the katzeye would need it as well. Just a thought
Also I assume you set the diopter adjustment....
Thanks for the idea, I checked but no, no shim with the standard focusing screen I removed. And actually the focus problem was there as well with the original screen, it was just so much more difficult to be sure, these digital cameras focusing screens being so transparent and fine grained, the eye can accommodate past the focusing screen, making secure focusing almost impossible (at least for me). No such doubt with the Katzeye though....
(by the way, this Katzeye is really a very nice focusing screen, not exactly cheap -and I didn't ask for the Optibrite treatment- but in the end absolutely worth it IMO)
07-01-2008, 09:04 PM   #13
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QuoteOriginally posted by ckanthon Quote
Thanks for your clarification on that: which meant it is the other way round... CCD plane is "fixed" Whereas AF sensor "plane" is adjustable (K10d debuging mode).
Not exactly. The AF sensor plane is to be adjusted *physically* (by the 3 screws underneath the body) whereas the software parameter of the AF detection algorithm can be tuned (via the Debug mode).
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