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05-09-2017, 04:51 AM   #1
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LX Mirror Rest Rubbers

I realise that adjustment will still be necessary but to get to a good starting point does anyone know the thickness/dimensions of the LX mirror rest rubbers which seem to have withered away ? I have found some rubber that seemed suitable and when in place the focus is not that far off but just wondered for reference if there is an ideal thickness.

Secondly can anyone suggest a procedure for adjusting the mirror for focus ? Is it basically adjust to infinity and trial and error ? taking the lens off and on 000's of time in the process ?

I can see the two adjusting screws, I really need an angled/offset No. 0 screwdriver by the look of it.

05-09-2017, 07:16 AM   #2
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You can directly estimate the offset by comparing the amount you have to turn the lens to get focus on the focusing screen versus focus on a piece of groundglass held against the film plane with the shutter locked open.

For simple prime lenses, each mm of turning of the circumference of the barrel shifts the lens by a tiny fraction of a mm (that fraction can be estimated by careful measurement of distances of turning versus distance of lens shift over the focusing range).

Next, focus carefully (on anything) using the viewfinder and note the exact barrel location.

Then, lock the shutter open (e.g., use bulb mode and a shutter release cable with lock screw), open the back of the camera, hold a sheet of ground glass (e.g., another focusing screen) against the film gate, refocus of the lens (a 10X loupe might help you seen the sharpeness of the image on the groundglass), and careful note the difference in barrel rotation between viewfinder and filmgate focus.

A bit of math and logic will tell you the bumper thickness difference you need to get the mirror in the right location.
05-09-2017, 08:45 AM   #3
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Many thank for that I didn't think of doing it taht way, it certainly seems better than the trial and error method !
05-09-2017, 09:09 AM - 1 Like   #4
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Another method that works well requires two things: 1. a lens that focuses exactly at infinity (50mm's are usually calibrated perfectly, test them on another body). 2. a view of a distant object (I use a church steeple a few blocks away).

With the lens and camera aimed at the distant object, your split image on the LX should show you how much adjustment you need to get the mirror perfectly aligned, either through bumper thickness, or adjustment.

If your lens is focused at infinity and your split image agrees, then you're done!

05-09-2017, 09:56 AM - 1 Like   #5
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QuoteOriginally posted by Ontarian50 Quote
Another method that works well requires two things: 1. a lens that focuses exactly at infinity (50mm's are usually calibrated perfectly, test them on another body). 2. a view of a distant object (I use a church steeple a few blocks away).

With the lens and camera aimed at the distant object, your split image on the LX should show you how much adjustment you need to get the mirror perfectly aligned, either through bumper thickness, or adjustment.

If your lens is focused at infinity and your split image agrees, then you're done!
Speaking of, you can bypass the physically clear distant object with this method: Camera repair pages
05-11-2017, 05:06 AM   #6
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I also noticed the the manual shows a tool used to set the mirror to 45 degrees which kind of makes sense. Although I would guess that is to provide a starting point only unless the tolerances in the rest of the camera are very tight ?

So far I've done it by using a lens trusted to be accurate at infinity (and verified mounted on the MX). Later I will compare it with the other methods to see how they all compare.

I started with a 200mm lens but that seemed to produce to big a tolerance when I then compared to the 50 and 28 mm, so in the end I primarily set to the 50mm and then just checked the 28 and 200 agreed.

Had to rob the mirror rest off another faulty body and felt gutted but still hope to get that one going too in time. May actually make a new bracket if I can't buy one.
02-04-2021, 09:26 AM   #7
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I know this is old, but how do you adjust the mirror?
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