G-Claron spacing...

Discussion in 'Large Format Cameras and Accessories' started by ruilourosa, Jul 25, 2012.

  1. ruilourosa

    ruilourosa Member

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    Hello


    Has anyone has done some experiments adding some spacing between g-claron´s lens groups and checked for improved shapness?

    just to know if it´s worth the ride...
     
  2. pgomena

    pgomena Member

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    Mine came with a brass spacer. I've not experimented with it further because it's sharp as is with the spacer in place. I figured someone before me knew more about the need for it than I did, and I left well enough alone. It sits in front of the rear element.

    Peter Gomena
     
  3. E. von Hoegh

    E. von Hoegh Member

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    Do you have an optical bench with the skill and experience to use it? if "no", just trust Schneider.:smile:
     
  4. ruilourosa

    ruilourosa Member

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    hello

    i asked beacause i heard that incresed spacing could benefit infinity sharpness at wide apertures!
     
  5. E. von Hoegh

    E. von Hoegh Member

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    It might. I've heard it was decreased spacing, though. It can't hurt to experiment, as long as you don't damage any threads or lose any spacers that might already be there.

    Clarons are very sharp lenses and you'll be hard put to see any difference with standard film holders.
     
  6. ic-racer

    ic-racer Member

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    If you have a way to check the corners for focus, then just unscrew the lens and test. If you know the pitch of the threads, you know how far out the lens comes with each revolution. I did some film tests with my Angulon 210 at various front/rear cell spacing. but went back to the factory specs. With that lens I it appeared that the focal "plane" was not so much a dish shape but more like a sinusoidal pattern of concentric rings like a drop of water in a puddle. As I got the very far corners to match the center, other areas of altered near or far focus would crop up at intermediate distances from the center. The factory spacing gave the best compromise.
     
  7. pgomena

    pgomena Member

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    At f/9, my 305 G-Claron does not have a particularly wide aperture at all. It also is not at its sharpest wide-open, but if that's due to cell spacing or to lens aberrations characteristic of the lens design, I have no idea. I do know that at f/16, it becomes very sharp.

    I once used it wide-open on my 4x5 to photograph distant fireworks. Focused at infinity, it was able to resolve the fireworks adequately for a nice 11x14-inch print. I can think of no other time I've used it at f/9.

    Peter Gomena
     
  8. ChuckP

    ChuckP Subscriber

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    Does anyone know if the spacing is the same for factory mounted shutter and barrel lenses? I see that Red Dot Artars did vary the spacing for shutter lenses. See http://www.cameraeccentric.com/html/info/schneider_4.html You have to go to the Red Dot Artar page to see what I'm referring to.
     
  9. ruilourosa

    ruilourosa Member

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    the spacing is exactly the same, barrel or shutter (compur 1) measured with a digital precision vernier! maybe someone with a digital adaptor (i am building one!!!) or digital back is willing to do some testing...
     
  10. E. von Hoegh

    E. von Hoegh Member

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    You'll need to check the corners, as well.
     
  11. ruilourosa

    ruilourosa Member

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    yes! i´m aware of that, thanks! but that way i can check some lenses fast!
     
  12. E. von Hoegh

    E. von Hoegh Member

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    And inexpensively.
     
  13. Leigh B

    Leigh B Member

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    More correctly... The NOMINAL spacing is the same. The actual spacing is a variable, not a constant.

    All manufactured items are built to tolerances. Lenses are no different.
    The parameters of each individual lens element all have tolerances,
    as do the dimensions of all the aluminum components.

    Front and rear lens cells are matched at the factory to achieve the desired functional specs,
    but those are also subject to tolerances.

    The cells are mounted at the factory, matched to the particular shutter, which also has tolerances.

    Since you don't have access to a large selection of cells to match to the particular shutter,
    I suggest it's highly unlikely that you'll improve on the performance of a factory-assembled lens.

    - Leigh