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03-04-2019, 05:40 AM   #1
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Pentax LX infinity focus issue -advice needed

Hello everyone,

I just got my hands on a Pentax LX with the standard viewfinder and a split-prism focusing glass.

My issue is the following. Using manual focus K-mount lenses, the split-prism is always just a hair off when focusing to infinity. However, using more modern autofocus K-mount lenses, I seem to be able to get it to focus accurately on the prism, as these lenses allow to go slightly past infinity.

My first roll of film that I shot specifically for testing is in development as we speak. So I’m not sure how much this issue actually translates to final images.

Could this be the beginning of the infamous sticky mirror syndrome acting up, pushing the mirror slightly out of alignment? Or is the focusing screen perhaps not correctly installed?

Given how expensive CLA’s are for this camera I’m looking to see if there’s anything I’m overlooking or I should just send it in?

Thanks in advance!

J.S.




03-04-2019, 09:25 AM - 1 Like   #2
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The LX mirror stops are often known to require service.
It can impact your photos as you will misfocus each shot.

Not sure who to recommend for LX repair in EU. Good luck!

Chris
03-04-2019, 09:32 AM - 1 Like   #3
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QuoteOriginally posted by jschoonj Quote
Hello everyone,

I just got my hands on a Pentax LX with the standard viewfinder and a split-prism focusing glass.

My issue is the following. Using manual focus K-mount lenses, the split-prism is always just a hair off when focusing to infinity. However, using more modern autofocus K-mount lenses, I seem to be able to get it to focus accurately on the prism, as these lenses allow to go slightly past infinity.

My first roll of film that I shot specifically for testing is in development as we speak. So I’m not sure how much this issue actually translates to final images.

Could this be the beginning of the infamous sticky mirror syndrome acting up, pushing the mirror slightly out of alignment? Or is the focusing screen perhaps not correctly installed?

Given how expensive CLA’s are for this camera I’m looking to see if there’s anything I’m overlooking or I should just send it in?

Thanks in advance!

J.S.
Indeed, it is. If you enjoy shooting film it will be well worth it. I bought a LX a few years ago and it is just a magical camera in my mind. Mine also had the sticky mirror problem and a trip to Eric Henderson in Tennessee in the U.S., brought it back to new. Don't know who to recommend you send it to in Europe. If you cannot find anyone, looking up Eric here in the U.S. might be a good idea. If that isn't an option, and you cannot find anyone in Belgium or Holland, give a call to FotoImpex in Berlin. I get there a couple times a year and there is a woman there who is all about the LX. She might be able to direct you to someplace. My daughter lives in Berlin - if you can't get an answer let me know and I will have her swing past the shop and see if she can get some information for you.

Tony A.
03-04-2019, 10:04 AM - 1 Like   #4
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Each of the causes has a different effect:

1) A misaligned mirror will have the largest effect on infinity focus at the top of the frame (and almost no effect on infinity focus at the bottom of the frame).

2) A mis-installed focusing screen affects infinity focus across the entire frame by the same amount.

3) Damage to the lens mount or body can affect infinity focus across the frame but is likely to be worse on one side or one corner versus the other.

Note: if you check infinity focus with small piece ground glass sitting flat on the film rails, then causes #1 and #2 will show a discrepancy between focus on the film plane versus focus in the viewfinder. Cause #3 will also affect infinity focus at the film plane.


Last edited by photoptimist; 03-04-2019 at 10:54 AM. Reason: typos
03-04-2019, 10:10 AM - 1 Like   #5
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In Germany, you could ask Kamerazeit Reparatur folgender PENTAX Kameramodelle - Kamerazeit They don't list the LX but it's worth a try.

Then there is HOST-Photoservice | Startseite , also in Germany.
03-04-2019, 10:49 AM   #6
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QuoteOriginally posted by photoptimist Quote
Each of the causes



1) A misaligned mirror will have the largest effect on infinity focus at the top of the frame (and almost not effect on infinity focus at the bottom of the frame).



2) A mis-installed focusing screen affects infinity focus across the entire frame by the same amount.



3) Damage to the lens mount or body can affect infinity focus across the frame but is likely to be worse on one side or one corner versus the other.



Note: if you check infinity focus with small piece ground glass sitting flat on the film rails, then causes #1 and #2 will show a discrepancy between focus on the film plane versus focus in the viewfinder. Cause #3 will also affect infinity focus at the film plane.


Thanks everyone for your comments!

Taking into account the above, it seems like a misaligned mirror since the bottom of the frame looks to be more in focus than the top.

I’ll be sending it over to Cor van den Haspel from http://www.camerareparatie.nl
He came highly recommended by my local camera shop, and did a fabulous job on restoring my Spotmatic II. Even changing out the entire prism at no extra cost.

I feared he completely stopped work on analog cameras since it took so for him to respond, but he just quoted me €45 to alleviate the problem and check if any additional work needs to be done before sending it back over.

Looking forward to having my Pentax LX in perfect working order. It looks to be in perfect condition concerning everything else. Even still had the protective foil on the bottom plate!

Thanks again to everyone who responded!

J.S.


03-04-2019, 10:51 AM - 1 Like   #7
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QuoteOriginally posted by photoptimist Quote
if you check infinity focus with small piece ground glass sitting flat on the film rails
I've also seen it done with translucent scotch tape. (not the clear kind.) I've seen people use that method to adjust rangefinders.

Geof

03-05-2019, 06:18 AM - 1 Like   #8
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The LX I owned back in the early 2000’s did not focus properly at infinity. I finally bit the bullet and sent it to Pentax for a complete CLA. This was just before Pentax quit servicing the LX. The issue was the mirror stops.
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