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Thread: rangefinder loses infinity

  1. #1
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    rangefinder loses infinity

    just found my rangefinder won't superimpose on very distant objects although the lens is up to the inf stop. happens with all my lenses. images seem to be in focus at inf, just not indicated so in the rangefinder. never bumped the camera; had it checked out in NJ several months ago and it was fine then. anyone seen this loss of range finding?

    jm

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    Sr. Administrator Jack's Avatar
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    Re: rangefinder loses infinity

    John:

    Sounds like you need to set the infinity adjustment on your body. It is pretty common to have this change over time in M bodies, especially if you change lenses a lot. Fortunately, this is also the easy one to do It is the small roller right at the throat of the body; a 2mm allen adjusts the eccentric the roller is mounted to. Tiny adjustments are usually all that are required, like moving the end of the wrench 1mm at a time or like one minute on a 60 minute clock face. Try CCW first if you're not quite hitting infinity. However, be advised that adjustment may alter the total focus arm length pushing close focus off, though not likely to be a significant change unless your infinity is way off to begin with. (The arm pvot adjustment is back inside the camera at the other end of the arm and more difficult to make.)

    FWIW, I use a star as my "infinity" reference point as it's really easy to see mis-alignment. A light or vertical tower a mile or more away also works.

    Cheers,
    Jack
    home: www.getdpi.com

    "Perfection is not attainable. But if we chase perfection, we can catch excellence."

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    Administrator Bob's Avatar
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    Re: rangefinder loses infinity

    John:
    Note that Jack said tiny adjustments. He really meant TINY.
    I carefully sight along the arm of the allen wrench to gauge the amount of adjustment being applied. I suggest perhaps 0.5 mm of motion at the end of a typical 75mm long allen wrench. More than that, and you are liable to completely overshoot the mark.
    -bob

    p.s.
    be careful not to mar the flat black paint at the end of the roller lest the next time you send it into Leica they charge you $94.00 for a replacement arm.

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    Re: rangefinder loses infinity

    saw this in another thread:
    http://www.dantestella.com/technical/leicadjust.html

    seems like an informed review...doesn't mention the tendency for the RF to get out of whack however, from simply switching lenses.

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    Administrator, Instructor Guy Mancuso's Avatar
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    Re: rangefinder loses infinity

    John if it is infinity if you have the camera upside down to make the adjustment go RIGHT with the allen wrench a fraction, than check it
    Photography is all about experimentation and without it you will never learn art.

    www.guymancusophotography.com

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    Subscriber robsteve's Avatar
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    Re: rangefinder loses infinity

    How are your lenses focusing? Did the images ever align at infinity?

    When Leica sets up the rangefinder, they use a target with reticle lines offset a bit to simulate infinity. They also need to balance the near focus adjustment to the infinity focus and make sure the 10m distance is accurate. At either either end of the adjustment range there is a tollerence of a reticle line thickness. In other words, when you are looking at a very distant object, the infinity may be very slightly off, but the techinician had to set it that way to get the 10m and near focus right.

    Robert

  7. #7
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    Re: rangefinder loses infinity

    Recently I receive my Black M8 back for NJ and while it was there I ask them to check the focusing.
    When I got it back I mounted my 50 Summilux on it and found that it DID NOT focus correctly, it backfocused. I then set out to find out why becasue on my Chrome M8 the 50 Lux is fine.
    Doing the infinity focus with the 50 Lux and 75 Cron showed that the images were not lining up, IE they did NOT get TO each other. This means that you had to turn the lens to a father distance setting to get the Range/Viewfinder images to coincide which will give you backfocus. So I adjusted it, got it to where I think the images are lined up, and then did some minor tests checking more for sharpness of focus point then worrying about how much in front of or in back of the focus point the DoF covered.
    Then last night it was incredibly clear here in Atlanta with a nearly full moon. So I set out to mount every lens I have on the black body and check infinity focus, in repect to how the the images lined up in the View/Rangefinder. The results were startling.
    With every lens I own, except the 50 Lux and 75 Cron, the Range/Viewfinder images went PAST each other to some degree, more with some then with others and my 50 Cron was about as close as the 50 Lux and 75 Cron but still past slightly.
    I then set out to do some focus test with all lenses on both bodies.
    I didn't try to be to precise with the focusing. I'd mount the lens, adjust the focusing ring and when my test target image came into what I thought was good focus I took the shot. Only a few time did I go past focus and then back and then back again.
    The result from the focus tests showed that all my lenses had GOOD FOCUS @ the POINT i was focusing on.
    So it seems that Leica lenses are not all calibrated to set the range/viewfinder to true overlapping images when they are set to infinty.

    So John I would do some test with your various lenses at different focusing distances to see if the images they produce are acceptable, and of course do some near controlled focus tests to see if they are really focusing correctly, before I'd adjust the infinity focusing cam.

    My test opened my eyes as to what can happen with a multiple lens Leica M kit.

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    Subscriber robsteve's Avatar
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    Re: rangefinder loses infinity

    Leica uses a jig to set up the focusing distances. It mounts like a lens and has the three focusing distances on it. If you don't have this tool, a Leica tech told me the 90mm lenses are the best to use for setting the infinity setting.

    Robert

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    Re: rangefinder loses infinity

    i did reset mine using the allen and got objects at infinity to superimpose and be in focus as they used to. I bums me out this setting can go out with normal use.
    I seems that if was good once, if it goes out, you get back without causing other complications.

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    Subscriber Member jaapv's Avatar
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    Re: rangefinder loses infinity

    Quote Originally Posted by jlm View Post
    i did reset mine using the allen and got objects at infinity to superimpose and be in focus as they used to. I bums me out this setting can go out with normal use.
    I seems that if was good once, if it goes out, you get back without causing other complications.
    Hey man! it is a mechanical design from the fifties!It needs some maintenance.
    JAAP
    http://www.jaapvphotography.eu
    The colours of my generation are black and white.

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    Re: rangefinder loses infinity

    me too, but from the forties

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