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03-28-2010, 06:31 PM   #1
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Shim replacement works - K7 focus screen

Hi all.

For those that followed my thread regarding the Katz Eye focus screen and the issue of the shim, I have received my set of shims and am happy to report that the shim replacement seems to have worked correctly. I have only done preliminary testing, but a .20mm shim seems to be about right.

Here is my original thread on this site:
https://www.pentaxforums.com/forums/pentax-dslr-discussion/94154-things-you-l...ye-screen.html

As those who read my original thread may remember, the factory fitted shim of .40mm caused front focus compared to what appears in the VF. In otherwords, my focused point in the VF would be behind what was actually recorded on the sensor. When I removed the .40mm factory fitted shim, the recorded image onto the sensor moved to behind the correctly focused image in the VF when I composed the image - to about the same amount as when the shim was installed. So, I figured that the factory fitted shim of .40mm needed to be about .20mm and this seems to be correct by my preliminary testing.

03-28-2010, 07:23 PM   #2
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Well done. And good seeing you on the forum
03-28-2010, 07:30 PM   #3
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Thanks for the update, Lance. I'm gonna do something about mine. Can't get the factory replacement, probably just cut some 3M paper and see how. Now I just turn the lens a bit further after the split is on (focused) so to get better results, works okay most time, but kinda defeat the purpose of using a split screen
03-28-2010, 08:47 PM   #4
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♠I finally got my screen dialed in today using a 50/1.2 wide open. I also found the .20mm shim was the best.

03-29-2010, 12:33 AM   #5
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QuoteOriginally posted by Jonson PL Quote
Well done. And good seeing you on the forum
Thanks for that, Sune.

I really should post "here" more than "there" as "there" is not a very nice place to be nowadays, hence the fact that I post a lot less over "there".
03-29-2010, 12:34 AM   #6
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QuoteOriginally posted by frank Quote
Thanks for the update, Lance. I'm gonna do something about mine. Can't get the factory replacement, probably just cut some 3M paper and see how. Now I just turn the lens a bit further after the split is on (focused) so to get better results, works okay most time, but kinda defeat the purpose of using a split screen
I understand your dilemma.

I would certainly attempt to get the Pentax shims as they are correctly gauged and in .05mm increments from .10mm to .50mm. It may be a bit hit and miss with 3M paper.
03-29-2010, 12:35 AM   #7
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QuoteOriginally posted by Wheatfield Quote
♠I finally got my screen dialed in today using a 50/1.2 wide open. I also found the .20mm shim was the best.
Good to hear!
03-29-2010, 12:36 AM   #8
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Was the focusing screen really that much of an improvement to justify all the hassle you seem to have gone through?

03-29-2010, 12:47 AM   #9
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QuoteOriginally posted by noahpurdy Quote
Was the focusing screen really that much of an improvement to justify all the hassle you seem to have gone through?
Depends on if you like to use fast manual lenses I guess. For me, I more or less rely on the AF confirmation instead of the split now since the split screen isn't properly calibrated. Used to use the same screen on K20D, results were much better.
03-29-2010, 01:11 AM   #10
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Have the same problem with AF lens as the split is slighly off.
Removed the K3 screen (with grids) when I sold my K7 before getting the Silver Limited.
With the "golden section ratio” focusing screen, I may have to rely more on judgement of sight for manual focus lenses.
03-29-2010, 04:04 AM   #11
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I've just been through this process myself on a K20D.

1. Never completely happy with accuracy of AF, nor my MF abilities at f1.4-f2.0.
2. Took an informed punt and installed a Katzeye - much better in MF but front focussed enough to be annoying.
3. Installed 0.15mm shim (had 0.25mm), MF now spot on, results with AF also much better.

AF improvement has been the result of using the split screen to verify AF point selection. The AF system cannot benefit directly from the split screen, but the ability to see accurately what the AF is trying to focus on has led to a vast improvement in the ratio of inut focus shots.

No regrets, wish I'd installed one years ago.
03-29-2010, 04:45 AM   #12
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QuoteOriginally posted by noahpurdy Quote
Was the focusing screen really that much of an improvement to justify all the hassle you seem to have gone through?
Yes. When using a fast lens with a large aperture therefore with a very shallow DOF and you have manually focused on a specific spot, then find that the camera has inadvertantly focused either behind or in front of that spot, then it is worth the hassle.
03-29-2010, 04:46 AM   #13
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QuoteOriginally posted by jawsy Quote
I've just been through this process myself on a K20D.

1. Never completely happy with accuracy of AF, nor my MF abilities at f1.4-f2.0.
2. Took an informed punt and installed a Katzeye - much better in MF but front focussed enough to be annoying.
3. Installed 0.15mm shim (had 0.25mm), MF now spot on, results with AF also much better.

AF improvement has been the result of using the split screen to verify AF point selection. The AF system cannot benefit directly from the split screen, but the ability to see accurately what the AF is trying to focus on has led to a vast improvement in the ratio of inut focus shots.

No regrets, wish I'd installed one years ago.
Couldn't agree more.
03-29-2010, 06:49 AM   #14
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I had spoke with Rachael at Katzeye when the K7 Silver with the "golden section ratio” focusing screen came out(been thinking about a screen) and sent her the image of the screen. She said she would make the screen for any one that would like it at no additional cost compared to any other screen,rule of thirds,ect....just thought I would share,I have no affiliation with her or Katzeye....
03-30-2010, 09:44 AM   #15
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Spent quite some time to calibrate the K3 split screen on my K7, I found manual focusing is the most accurate w/o a shim at all. I tried a few DIY shims at different thickness, all seem to make the focusing slightly to the front. When I take out the shim (including the original one of course), the split is in line w/ the AF result, and my K7's AF is pretty much spot on w/ most of my lenses including FA77 and FA31.

Now I'm much happier w/ the manual focusing result. Pity the K3 screen got a few light marks during the trials
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