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04-13-2014, 01:50 PM   #1
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Problem w/Nikon K3 focusing screen on K30

I purchased a Nikon Type K3 focusing screen from Focusingscreen.com & installed it on my K30.
I checked the calibration using a 55 mm 1.8 K mount & 50 mm 1.7 A series lens and both lenses exhibit front focus when focused manually.
However, both lenses focus correctly in Live View so it looks like the problem lies with the focusing screen.
I checked the Focusingscreen.com web site but the English instructions aren't clear.
I suspect that I need to add a shim but before I dive into this further, I'd like to see if there are any K30 owners who encountered the same problem & what their solution was.
I appreciate anyone's help.

04-13-2014, 02:42 PM   #2
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You need a slightly thinner shim.
04-13-2014, 03:40 PM   #3
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If it's similar to the K20d--focussingsceen.com has included--or will send if requested--other shims; however, they are plastic.

Instead I found you can order metal ones--in a range of sizes from Pentax. They were inexpensive-the major cost is the shipping--so you can get a selection including larger/smaller/and same as the nominal one.
04-13-2014, 04:50 PM   #4
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Thank you for the replies.
Focusingscreen.com did include 3 plastic shims so I will have to experiment to see how many I will need to install.
It looks like to correct back focus, the shims must installed between the focusing screen & pentaprism.
So to correct front focus, do the shims need to be installed between the mirror & focusing screen?

04-13-2014, 05:23 PM   #5
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Putting the shim on the bottom side of the screen won't do anything, it must go between the prism and the screen. There is already a shim inside the camera, for front focus you need to remove it and replace it with a thinner one.

There were 3 shims with mine, a thick one in a bag and two thin ones in another bag. I used the thicker one, which is thinner than the original. I just measured mine and the original is 0.35mm, which seems to be normal for Pentax bodies and the two thin ones in the kit are 0.15mm each, I believe the one I used was 0.30mm.
04-13-2014, 06:00 PM   #6
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QuoteOriginally posted by elliott Quote
Putting the shim on the bottom side of the screen won't do anything, it must go between the prism and the screen. There is already a shim inside the camera, for front focus you need to remove it and replace it with a thinner one.
There are detailed instructions on at focusingscreen.com:

Focusing Screen--How to adjust focusing screen--

-- and--

--Pentax K3 K5 K7 K30 focusing screen front focusing revise guide--

The second link specifically addresses front focus.


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04-13-2014, 06:31 PM   #7
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On my K-x with this same screen, I had to find the right combination of shims. In my case I think one of their shims plus the original Pentax shim worked best. The process took me 2 solid hours of trial and error, until I was getting the most accurate focus. It was impossible to get it exact, but it was close enough to be good. And it was rather tedious - much of the time was spent trying to get 2 shims in at the same time.

In my case I got the screen a bit dirty in the process, but that was OK with me because it didn't affect the output IQ, of course. And my focus was better afterward.
04-13-2014, 08:33 PM   #8
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If you have the time I suggest you order/wait for the Pentax shims--the plastic ones are problematic--especially using 2 thin ones. The Pentax (K20d) are metal and far more positive to use.

If you fiddle around a lot you will get the screen dirty (e.g., above post)--and risk scratching it. This is a lot less likely with Pentax metal shim--assuming again it is similar to the K20d (metal) shims.

Above based on my experience--first used the plastic shims, and then redid using Pentax shims.

04-13-2014, 08:39 PM   #9
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I didn't have any problem with the plastic ones, they stay in place fine while you're positioning the screen. The K-5 could be different from the K20D though, the K100D was much less fun to do because the shim isn't held in place.
04-14-2014, 07:26 AM   #10
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QuoteOriginally posted by dms Quote
If you have the time I suggest you order/wait for the Pentax shims
Do you have the part number and how to order?


Steve
04-14-2014, 08:58 AM   #11
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For Pentax (metal) shims telephoned Pentax (USA) and ordered two of each thickness for K20d. No I don't know the part number for K3.
04-14-2014, 10:18 AM   #12
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QuoteOriginally posted by dms Quote
For Pentax (metal) shims telephoned Pentax (USA) and ordered two of each thickness for K20d. No I don't know the part number for K3.
Thanks. I did not know that they dealt directly with the public.


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04-14-2014, 12:39 PM   #13
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I just finished experimenting with the shims. I first tried removing the factory installed shim and replacing it with the thickest one provided by Focusingscreen.com and found that my K30 was still front focusing.
I then removed all shims and find that my camera is still front focusing. I'm now considering reinstalling the original matte focusing screen and shim.
04-14-2014, 12:51 PM   #14
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QuoteOriginally posted by gmiyamoto Quote
I just finished experimenting with the shims. I first tried removing the factory installed shim and replacing it with the thickest one provided by Focusingscreen.com and found that my K30 was still front focusing.
I then removed all shims and find that my camera is still front focusing. I'm now considering reinstalling the original matte focusing screen and shim.
That is very odd, my only thought is that the screen could be upside down. However my S type from them had the tab on it so I think that would be impossible unless they cut it wrong.
04-14-2014, 12:54 PM   #15
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I installed the focusing screen with the "rough side" facing up toward the pentaprism.
The smooth, shiny side is facing down toward the mirror.l
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