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  1. #11

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    Quote Originally Posted by Ian Grant View Post
    It's the aperture blades Brian
    Ian, please help me understand because I don't seem to know what folks mean when they say "have the aperture blades adjusted" or "calibrated". My experience on both old and new shutter is that they either work or don't (are broken) and they either accurately represent the indicated aperture number or don't (in which case I assume the scale is "adjusted" rather than the aperture mechanism itself). Please help me understand.

  2. #12

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    Quote Originally Posted by malcao View Post
    There is no problem having my Leica M4 checked and fixed, I had some Gossen Bisix and Sixon2 fixed without any problem. So there are companies out there that fix products that is "outdated".
    OK, I stand corrected. But that is why I said "generally".

  3. #13
    Ian Grant's Avatar
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    Quote Originally Posted by BrianShaw View Post
    Ian, please help me understand because I don't seem to know what folks mean when they say "have the aperture blades adjusted" or "calibrated". My experience on both old and new shutter is that they either work or don't (are broken) and they either accurately represent the indicated aperture number or don't (in which case I assume the scale is "adjusted" rather than the aperture mechanism itself). Please help me understand.
    I think it's the way we use English, Europeans in general seem to use language far more precisely than most Americans, I'd add Canadians to the European side. It's maybe because the US was and still is such a melting pot mainly of immigrants from all over the world.

    The OP says "adjust the aperture blades" the word blades in this case adds the detail, if he'd said adjust the aperture that would have been ambiguous and we'd assume the calibration.

    Yes you're right normally an LF shutter's aperture blades usually work or are broken, sometimes a blade pops out of place, they are known to physically break as in lose a bit of the blade. This particular shutter's unusual because the aperture part is accessible, normally with Compur's and Copal's it's behind the shutter mechanism which has to be removed first. So the OP was lucky he could repair it.

    But then OP strictly hasn't adjusted the aperture blades, there is no adjustment, they are either in or out of place, he's tightened up the parts that house them, and tightening is an adjustment.

    Aperture scales aren't usually adjustable, the adjustment/calibration comes in when there's the wrong or no scale for a particular lens/shutter combination.

    Hope that helps

    Ian

  4. #14

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    Quote Originally Posted by Ian Grant View Post
    ...
    Thanks... I have a better understanding now. Thanks.

  5. #15
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    If I had used an instrument to adjust the aperture blades I would have called it calibration, but since I didn't I used the word adjustment.
    Here are some photos
    Photo 1: Cam adjustment when the lens is wide open.
    Photo 2: Stop screws. My lens is 6.8 and when used here I could notice the aperture blades looking into the lens, I moved the screw one stop and no aperture blades could be seen, I suppose this is 5.6.
    Photo 3: Here you can loosen the screws and adjust how big or smal the aperture will be and the just tight the screws.
    I don't know if these possibilites are on all LF lenses, I think they are great features.


    http://gallery.me.com/ifotograf#100059

  6. #16
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    Thanks for clarifying, I have a Prontor Press and and a couple os Ibsor's (previous version) but there's no adjustments, same as the Compur & Copal's.

    Prontor shutters are not as common as Compur/Copal particularly the newer ones.

    Ian

  7. #17

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    Quote Originally Posted by malcao View Post
    Here are some photos
    My, my... that was educational. Thanks very much; I learned something new today!

  8. #18
    Ian Grant's Avatar
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    Brian & malcao, I wonder if that adjustment is to make sure the shutter's aperture blades can be adjusted to match the extra Adjusters that can be added. (Scroll down the page)

    With Copal's and Compur's the widest aperture is often controlled by the diameter or the inner elements, and the minimum will go past the smallest stop. A classic example is the 90mm Angulon where the aperture opens way past f6.8, in fact it's nearly half way before you rach that aperture. But with an additional device like the Prontor takes you need that more definite control of Min & Max apertures, particularly as the same shutter would be used by manufacturers with different lenses and need adjusting appropriately.

    Just a thought.

    Ian

  9. #19
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    contact skgrimes.com

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