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08-27-2010, 10:19 PM   #1
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Focusing screen weirdness aarrgghhh!

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I bought a focusing screen on ebay a 'Trevor' diagonal split screen. Installed the sucker ok. But now there's a problem.. The focusing is waaay off. I tested with about 5 lenses. The autofocus, focuses correctly and the image is still split! When I align it, it's out of focus.

If that wasn't weird enough, aligning the split screen with one of my lenses actually does focus it.... so.. what's going on? Is the split screen meant for a different camera or something? Anyone know if there's anything I can adjust?

I should mention, I have a k2000 and this is the screen i bought:

http://cgi.ebay.com/O5O2-Dual-45-Split-Focusing-Screen-Pentax-K2000D-/270510722935

08-27-2010, 11:27 PM   #2
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It isn't unusual to have to re shim a camera to make a new screen work.
08-27-2010, 11:56 PM   #3
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QuoteOriginally posted by Wheatfield Quote
It isn't unusual to have to re shim a camera to make a new screen work.
Oookk.. you may have noticed this is posted under Beginner's Corner.
Where can I get a shim or any info on how to make/apply one?
08-28-2010, 12:01 AM   #4
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Shims come in a variety of thicknesses and are available
directly from your local Pentax dealer. The part numbers are as follows:

76830.M02200A - 0.15mm
76830.M02200B - 0.20mm
76830.M02200C - 0.25mm
76830.M02200D - 0.30mm
76830.M02200E - 0.35mm
76830.M02200F - 0.40mm

The 0.25mm and 0.30mm are the ones most commonly supplied with the camera.
A front focus condition will require a thinner shim, as you have observed in
your test without any shim at all. The parts are very inexpensive (less
than $1 each), so it is probably best to just order one of each... or at
least the ones from 0.15mm to 0.30mm.

Good luck

08-28-2010, 12:45 AM   #5
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QuoteOriginally posted by Nass Quote
Shims come in a variety of thicknesses and are available
directly from your local Pentax dealer. The part numbers are as follows:

76830.M02200A - 0.15mm
76830.M02200B - 0.20mm
76830.M02200C - 0.25mm
76830.M02200D - 0.30mm
76830.M02200E - 0.35mm
76830.M02200F - 0.40mm

The 0.25mm and 0.30mm are the ones most commonly supplied with the camera.
A front focus condition will require a thinner shim, as you have observed in
your test without any shim at all. The parts are very inexpensive (less
than $1 each), so it is probably best to just order one of each... or at
least the ones from 0.15mm to 0.30mm.

Good luck
Ok, here's the thing. I stupidly left the original shim in there. Now that I've taken it out, it's still bad, but not as bad. Does this mean that I have to grind the focus screen down? Because it looks like adding a shim will just make it worse it seems.
08-28-2010, 01:25 AM   #6
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No it means you should use a different thickness shim. Don't alter the focusing screen
08-29-2010, 09:53 AM   #7
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QuoteOriginally posted by Nass Quote
No it means you should use a different thickness shim. Don't alter the focusing screen
You're right. I dug out a digital caliper and measured the screens, they're about the same size, plus there was a shim there already, so I definitely need to buy those shims. Unfortunately, no one around seems to carry them, so thanks for posting the product numbers!

08-29-2010, 10:05 AM   #8
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QuoteOriginally posted by koguma Quote
You're right. I dug out a digital caliper and measured the screens, they're about the same size, plus there was a shim there already, so I definitely need to buy those shims. Unfortunately, no one around seems to carry them, so thanks for posting the product numbers!
Depending on the adjustment, you can shim the shim with tape or some other very fine adhesive(just make sure it can be removed).

I have had good success with 3M tab tape which is very very thin and so I've used it to shim my shims for what I like to call micro calibrations when fine tuning my screens after installation.

FTR. you can order the shims from any Pentax dealer, though I've had much better success with respect to delivery times ordering them direct.
08-29-2010, 10:12 AM   #9
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Does the focus screen have the alignment tab on it? The first one of these knockoffs I purchased a few years ago did not. Therefore, it was possible to install it upside down. It displayed the exact behavior you describe. Otherwise, the others are likely correct, some adjustment is in order.

08-29-2010, 10:40 AM   #10
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I take it this screen helps you with focusing but does it really make it easier or is there some other reason for replacing??
08-29-2010, 12:10 PM   #11
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Yes, it helps. It's easier to see if focus is off. Mind you there's a downside too, the spotmeter is off.
08-29-2010, 10:16 PM   #12
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QuoteOriginally posted by JeffJS Quote
Does the focus screen have the alignment tab on it? The first one of these knockoffs I purchased a few years ago did not. Therefore, it was possible to install it upside down. It displayed the exact behavior you describe. Otherwise, the others are likely correct, some adjustment is in order.

Yeah, it's got the alignment tab. Is the number on that tab of any significance?
Just to make sure, that tab is supposed to be on the top righthand corner when facing your camera, right?
08-29-2010, 10:18 PM   #13
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QuoteOriginally posted by 96p993 Quote
I take it this screen helps you with focusing but does it really make it easier or is there some other reason for replacing??
Definitely helps. I used to shoot with an old film Minolta, it was all manual. I had forgotten the pleasures of a split screen. It makes focusing a lot easier, and most of my lenses are manual.
08-29-2010, 10:24 PM   #14
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QuoteOriginally posted by JohnBee Quote
Depending on the adjustment, you can shim the shim with tape or some other very fine adhesive(just make sure it can be removed).

I have had good success with 3M tab tape which is very very thin and so I've used it to shim my shims for what I like to call micro calibrations when fine tuning my screens after installation.

FTR. you can order the shims from any Pentax dealer, though I've had much better success with respect to delivery times ordering them direct.
I spent a number of hours this past Saturday cutting up paper shims of various sizes. I've come to the conclusion that I'm better off ordering the parts. One store though told me there's a lead time of 8-10 weeks, so if I don't find a local store carrying them I'll order them direct from Pentax myself.
08-29-2010, 10:34 PM   #15
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Wow, you guys are much more camera savvy/braver than I am, can't imagine changing a focusing screen or any other internal part on mine.

Last edited by Bob photo 4 life; 09-07-2010 at 11:26 AM.
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