Mounting Lens to Lensboard

Discussion in 'Large Format Cameras and Accessories' started by Marvin, Jun 18, 2011.

  1. Marvin

    Marvin Member

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    Is there anything special about mounting a lens to a lensboard other than having the right tool to tighten it?
     
  2. Ian Grant

    Ian Grant Subscriber

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    Not really except some lenses have a locating pin that fit's into a small slot cut into the circular hole. You don't really need a lens spanner you can tap the retaining ring tight with a little piece of hardish wood/dowelling cut to a point.

    Ian
     
  3. Leigh B

    Leigh B Member

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    I always use the anti-rotation pin. Its purpose is to keep the shutter from rotating and possibly coming loose due to frequent manipulation of its controls.

    The pin is 2mm (0.080") in diameter. Its hole is located on the shutter mounting hole circle, extending 1mm outward from it, usually at the 12 o'clock position. The diameter and depth (radial) of the pin hole are not at all critical. You can use a small triangular file to cut it.

    Correct shutter hole diameter is important. The hole is a bit larger than the shutter mounting thread, to accommodate the locating ridge on the inner surface of the retaining ring. I don't know why they did it this way, possibly to prevent damage to the shutter threads.

    The correct hole diameters are:
    Copal 0 - 34.8mm
    Copal 1 - 41.8mm
    Copal 3 - 64.2mm (has no anti-rotation pin)

    The shutter hole should be bored (not drilled) by a machinist, or finished by someone with the proper tools to ensure that it's round, not scalloped.

    Some suggestions for mounting shutters:
    1) Open the shutter blades using the preview lever.
    2) Open the aperture fully using its control lever.
    3) Remove both front and rear cells. Be careful to locate and save any shims that might be present.
    4) Whenever possible, hold the shutter with its threads downward, to prevent junk from falling into it.
    5) Make sure the pin is seated and the retaining ring ledge is in the mounting hole before tightening.
    6) Remount both cells (with shims if present).

    nb - NEVER put your fingers or anything else in the shutter throat. You could damage the blades.

    If you need an anti-rotation pin, you can buy one for $1 from SK Grimes http://www.skgrimes.com


    - Leigh
     
    Last edited by a moderator: Jun 19, 2011
  4. Martin Aislabie

    Martin Aislabie Subscriber

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    Its worth working out what orientation you want the lens to be at before you mount it.

    Personally, I prefer my main controls to be be mounted at the top of the lens - while others prefer them mounted to one side.

    Its a personal choice - no right or wrong way - just what ever works for you.

    If you have never thought about it - just check your other lenses - its easier to operate them blind (by feel) from beneath the darkcloth if they all share the same basic positioning of the controls.

    Martin
     
  5. Leigh B

    Leigh B Member

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    Good point. I meant to mention shutter orientation in my previous post but forgot. :sad:

    The 12 o'clock position for the anti-rotation pin will put the normal shutter controls on the top, with the cable release on the left and the preview lever on the right (looking from in front of the camera).

    I'm able to rotate my lensboards when mounting to the camera, to change the shutter orientation as desired. I usually put the controls to the left and the cable release on the bottom.

    If you can't rotate your board when mounting, you'll need to choose a location for the anti-rotation pin.

    - Leigh
     
    Last edited by a moderator: Jun 19, 2011
  6. Sirius Glass

    Sirius Glass Subscriber

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    The orientation is probably specific to each camera. For my Pacemaker Speed Graphic the shutter needs to be at 9 o'clock to use the body shutter release. For the Graflex Model D the f/numbers need to be in the 6 o'clock position for access because of the folding lens hood.
     
  7. darinwc

    darinwc Subscriber

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    Also, press cameras may only close if the shutter is in a certain position. Just something to be aware of..
     
  8. Leigh B

    Leigh B Member

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    Good point.

    If you expect the camera to close with the lens mounted, your options for both lens and shutter may be quite limited.

    - Leigh