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Thread: 355 G-Claron Lens Cell Spacing

  1. #1
    funkadelic
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    355 G-Claron Lens Cell Spacing

    I was able to source a Copal 3 shutter for my 355mm G-Claron which as been living in a barrel mount. The lens cells fit the Copal 3 shutter the same as the barrel.
    I recall reading somewhere that the spacing is different between the two versions, but can't seem to find any reference online.
    I'm looking for the distance from the front of the front element to the back of the rear element. In barrel mount, it is 80mm for this distance.
    Do any of you have a factory mounted 355 G-Claron in shutter that you could measure for me?
    Thanks,

    Chris

  2. #2
    Tracy Storer's Avatar
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    Re: 355 G-Claron Lens Cell Spacing

    Measure the length of your barrel, if it's different from the thickness (at the threads front and back) of a Copal #3, you have your answer.

    Mine in Copal is 79.6+mm, but I don't think it's an original factory mount and my current measurement method isn't ideal.
    Tracy Storer
    Mammoth Camera Company tm
    www.mammothcamera.com

  3. #3
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    Re: 355 G-Claron Lens Cell Spacing

    I have a PDF downloaded from the Schneider Archive site for these lenses in shutters. It gives the overall length as 79.7mm. The printing date was August 1998. It's here:

    http://www.schneider-kreuznach.com/archiv/pdf/gcn.pdf

    An older (1982) brochure for barrel mount versions also gives 79.7mm as the length. That's this one:

    http://www.schneider-kreuznach.com/a...pdf/gcn_82.pdf

  4. #4
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    Re: 355 G-Claron Lens Cell Spacing

    When I looked at the older brochure a little more closely I noticed that it actually gives data for both barrel and shutter mounts. The shutter-mount lengths match those in the 1998 publication. The only lens that has different lengths for the two mounts is the 150mm, all the other focal lengths list the same overall length for either mount.

    150mm: shutter = 34.7mm, barrel = 36.2mm

    210mm: shutter = barrel = 49.0mm

    240mm: shutter = barrel = 53.5mm

    270mm: shutter = barrel = 60.8mm

    305mm: shutter = barrel = 68.9mm

    355mm: shutter = barrel = 79.7mm

  5. #5
    Tracy Storer's Avatar
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    Re: 355 G-Claron Lens Cell Spacing

    Good get, Steve.
    Tracy Storer
    Mammoth Camera Company tm
    www.mammothcamera.com

  6. #6
    funkadelic
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    Re: 355 G-Claron Lens Cell Spacing

    No doubt... and a good one for the archives.
    Thanks Steve!

  7. #7
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    Re: 355 G-Claron Lens Cell Spacing

    One thing to keep in mind is that the documents don't say anything about whether a spacer is needed for one mount or the other to achieve the correct overall length, or possibly the spacing(s) to the iris.

  8. #8
    Lachlan 717
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    Re: 355 G-Claron Lens Cell Spacing

    Chris,

    I'll get the digital calipers onto mine today to show you the ring-to-ring distance. It might help...
    Lachlan.

    You miss 100% of the shots you never take. -- Wayne Gretzky

  9. #9
    funkadelic
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    Re: 355 G-Claron Lens Cell Spacing

    I was reading an analog caliper. I'm sure it's good at "80ish". It would be hard to get fractions on it.
    Thanks anyway.

  10. #10

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    Re: 355 G-Claron Lens Cell Spacing

    Chris, your 355/9 G-Claron is probably a plasmat type. If so, you shouldn't worry.

    A while ago I innocently mounted a set of 150/5.6 Boyer Saphir BX cells in an ex-Polaroid CU-5 Copal Press shutter. Turns out that these shutters don't conform to the Compur/Copal/Prontor #1 shutter standard, their tubes are around 0.3 mm longer than the standard.

    When I measured and found this out I asked my friend Eric Beltrando to see what that increase in cell spacing would do to the lens' performance. Eric has written a ray tracing program, you can read about it and many lenses on his site www.dioptrique.info. He replied that the error in spacing was 0.2% of the lens' focal length, that plasmats -- that's what the BX is -- aren't very sensitive to small spacing errors, and that I shouldn't worry.

    So enjoy your lens and stop worrying.

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