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  1. #11

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    Hi

    Shoot some film before worrying about shutter speed, the shutter speed of the Leica three post shutter is much less critical than uneven exposure across the frame which can be intermittent..., e.g. dependent on temperature.

    Taking any camera back to a shop staffed by 'cowboys' is untoward.

    Noel

  2. #12
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    I sent an e-mail to the camera shop after fielding comments from here, Rangefinder Forum, and the Zorki Flickr group. They sent back an email explaining that there wasn't any risk in changing the shutter speeds—which is correct for this camera. I responded by explaining if it were the model with the slow speeds, they might have busted it (and the underlings didn't know there was a difference in the first place). Best case scenario, they didn't know what speeds they were testing, so I didn't even know what they were testing.


    The shop owner responded: "I'll make sure they test by changing the shutter speeds first from now on—there's no extra effort in doing it, so we might as well." He asked me to bring the camera in so he could test it himself. When he did, he got stable enough shutter speeds for his taste (he thought the 1/500 was going too fast until I told him there was a mystery 1/1000 right next to it).


    He did tell me, however, that the shutter curtains are timed so that there is uneven exposure across the frame by ±1/3rd of a stop. He said it's probably something that cannot be adjusted out (changing it at one speed would make the problem worse on other speeds), and it shouldn't show up too much in pictures.


    I emailed Yuri at Fedka.com, and he said he agrees: that's about as good as it gets. I'm inclined to agree, but I don't know squat about cameras.


    What do you guys think? (;

  3. #13

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    Had a Zorki 4 several years back. I only used the wrong sequence once, and it jammed the camera. Rendering it unusable. It took several good minutes of playing with the settings to fix. But, you live & you learn.

  4. #14

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    Hi, the way the Lieca shutter is designed takes care of the 'uneven' exposure. Basically the gap of the shutter increases slightly as it runs off, thereby increasing exposure - this is because the shutter blinds accelerate from a standing start so are travelling faster when the reach the other side of the frame, and if the gap remained the same, under exposure of the last part of the negative would occur.. If you take the back off the camera and slowly wind the shutter, you will see the opening curtain capping increases as the shutter is wound.
    The Contax, on the other hand, does not need this feature as the blinds run vertically and the difference in exposure is comparatively much less and can be tolerated.

    Hope this helps,

    Steve

  5. #15
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    Quote Originally Posted by Kiev88user View Post
    Hi, the way the Lieca shutter is designed takes care of the 'uneven' exposure. Basically the gap of the shutter increases slightly as it runs off, thereby increasing exposure - this is because the shutter blinds accelerate from a standing start so are travelling faster when the reach the other side of the frame, and if the gap remained the same, under exposure of the last part of the negative would occur.. If you take the back off the camera and slowly wind the shutter, you will see the opening curtain capping increases as the shutter is wound.
    That's the way the Zorki 4 curtains work also, right? I can see the capping increase as I wind it. Why is it more of a problem for Leica III-inspired Russian RFs than actual Leica IIIs? Just better workmanship?

  6. #16

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    Yes, it is down to quality. Leica used ball bearings and well machined bushings whereas the Russian copies do not. These copies also used poor quality lubricants which separate into grease and oil. All this causes wear and increases friction, making shutter fade more likely. Often people try to compensate by over tensioning the opening curtain, or both curtains to overcome the friction. This just increases the wear. I'm just trying to fit new curtains to a Zorki 3M (wish I'd never started) - the wear on the bearing surfaces is clear to see. The problem with the 'new old stock' curtains is that they have stiffened and do not want to wind around the drums, making this a nightmare job. Think I'll stick with my Contax II !!

    Cheers,

    Steve

  7. #17
    AgX
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    Quote Originally Posted by ntenny View Post
    I've been inside a Mir shutter,...
    Could you explain what lies behind that warning technically?

  8. #18

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    (in response to my experience of working on a Mir shutter)

    Quote Originally Posted by AgX View Post
    Could you explain what lies behind that warning technically?
    Not really, because the Mir doesn't have the slow speeds, and it seems the slow-speed escapement is what can really be damaged.

    The shutter-speed dial is on a shaft that rotates with the movement of the shutter curtains, so it spins when you cock the shutter and then spins back in the other direction at release (you can see this from the outside). In the cocked state, the shaft is aligned so that the speed dial will point to the right value on the surrounding ring (which doesn't move with the shaft). So if you set the speed to read to, say, 1/50 in the *uncocked* state, the actual orientation is basically some random position.

    It's been years since I was doing this, but as far as I remember, the only thing that the speed setting changes is the angle of a little cam on the shaft. The release is a two-step process: when you press the button it fires the first curtain, and when that little cam comes around to a certain point in the rotation of the speed shaft, it trips a release for the second curtain. The shorter the rotation to bring the cam into contact with the release, the faster the shutter speed. There's an explanation at http://rick_oleson.tripod.com/index-131.html, which indicates that the Leica II used the same basic mechanism.

    As far as I could tell, you couldn't actually damage anything by misaligning the speeds this way on a Mir (or a FED-2, which also doesn't have any slow speeds); you'll just get the dial in the wrong position and shutter speeds that have nothing obvious to do with the reading on the dial, and setting the speed while the shutter is cocked should fix that misalignment. I didn't understand every bit of the workings, though, and I certainly didn't make any exhaustive search for ways to break the mechanism---but I *think* actual mechanical damage is not readily available.

    By all accounts the models with the slow-speed escapement are another kettle of fish and you *can* break them by setting the shutter at the wrong time, but I don't know what the failure mode is.

    -NT
    Nathan Tenny
    San Diego, CA, USA

    The lady of the house has to be a pretty swell sort of person to put up with the annoyance of a photographer.
    -The Little Technical Library, _Developing, Printing, And Enlarging_

  9. #19
    AgX
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    Many thanks for that explanation!

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