Adjusting Compur/Copal shutter speeds

Discussion in 'Camera Building, Repairs & Modification' started by paul_c5x4, May 11, 2009.

  1. paul_c5x4

    paul_c5x4 Subscriber

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    Testing the shutter speeds on my (small) collection of shutters, I find the speeds faster than 1/100 sec are way out. For example, Copal:

    1/125 measured at 1/83
    1/250 measured at 1/166
    1/400 measured at 1/166

    Syncro-Compur

    1/100 measured at 1/86
    1/250 measured at 1/123
    1/500 measured at 1/117

    Compur-Rapid

    1/10 measured at 1/15
    ....
    1/100 measured at 1/80
    1/200 measured at 1/107
    1/400 measured at 114

    Most of the other speeds were within 10%, and a few, spot on. Apart from the fastest speed on each shutter, I'd kinda hoped for reasonably accurate timings - Not wanting to send the mechanisms away for a CLA, is there anything that I could do to improve the speeds ?
     
  2. ic-racer

    ic-racer Member

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  3. jon koss

    jon koss Subscriber

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    Sometimes bad results implicate the test and not the subject. Are you certain that your test method is reliable?

    Best,
    J
     
  4. paul_c5x4

    paul_c5x4 Subscriber

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    Repeated the tests again this morning, and the results are within 2% or so.

    Seems there are quite a few places selling the Rollie manuals. Reluctant to shell out $35+$13 without knowing if the required information is included. Looks like ebay #360153020687 would cover two of the shutters in question.

    Googling with a better search parameter, I found http://www.suaudeau.eu/memo/rep/Compur-shutter-repair-manual.html.

    I would imagine Copal shutters would be similar in terms of cleaning and adjusting.
     
  5. jfdupuis

    jfdupuis Member

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    When you measure high speed leaf shutter opening time, you need to think about the effective opening time. For that, I think you need to integrate the amount of light that pass through and not just looking at the opening and closing time.

    When calibrating my shutter using a phototransitor and my sound card, I realized that the highest speed are off quite a bit. About 0.20 stop at 125, 0.5 stop at 250 and about a full stop at 500. The other speeds are within 0.10 of a stop. Since I'm not able for now to get the DC component of the signal, I can't validate my assumption. As soon as I can get my hands on a DAQ card, I will check if integrating the signal make a more sense.