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Thread: Calibrating a Zone VI compensating developer timer

  1. #1

    Calibrating a Zone VI compensating developer timer

    My zone vi compensating developer timer is running too fast at higher temperatures. It works well enough from about 66F to 70F. Inside the unit there are two adjustment screws labeled PCAL and RTCAL. Does anyone know what these do, and the method for calibrating?

  2. #2

    Re: Calibrating a Zone VI compensating developer timer

    Have you run test with test negatives and a densitometer at different temperatures to conform that it s running to fast.
    As the temperature goes up it is not a linear increase. Paper and film have different curves. Kodak has papers on this if you can find then.
    Richard T Ritter
    www.lg4mat.net

  3. #3

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    Re: Calibrating a Zone VI compensating developer timer

    Even without tests the standard calibration should match. I think film is calibrated to Tri-X. So your results should match the time/temperature chart for Tri-X

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    Re: Calibrating a Zone VI compensating developer timer

    Note for future reference: Picker writes about the compensating timer in newsletter number 41 December, 1984

    Should be good for all film, all paper. The paper curve is steeper than the film curve.

  5. #5

    Re: Calibrating a Zone VI compensating developer timer

    The timer was calibrated to film developers not film.
    Richard T Ritter
    www.lg4mat.net

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    Re: Calibrating a Zone VI compensating developer timer

    Quote Originally Posted by Edward Pierce View Post
    My zone vi compensating developer timer is running too fast at higher temperatures. It works well enough from about 66F to 70F. Inside the unit there are two adjustment screws labeled PCAL and RTCAL. Does anyone know what these do, and the method for calibrating?
    It sounds to me that it might be working correctly; as the solution in the tray warms up, the timer will go slightly faster in order to “compensate” for the higher temperature.

    One of the ones I still have, did run obviously faster - it raced, regardless of the temperature. Zone VI (they were still around) fixed it. I has worked fine ever since.

  7. #7

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    Re: Calibrating a Zone VI compensating developer timer

    Quote Originally Posted by RichardRitter View Post
    The timer was calibrated to film developers not film.
    Hi Richard,

    Was wondering if Paul Horowitz is still around?

    Thanks, Luis

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    Re: Calibrating a Zone VI compensating developer timer

    Quote Originally Posted by Luis-F-S View Post
    Hi Richard,

    Was wondering if Paul Horowitz is still around?

    Thanks, Luis
    https://en.wikipedia.org/wiki/Paul_Horowitz
    Keith Pitman

  9. #9

    Re: Calibrating a Zone VI compensating developer timer

    If he is, there is nothing he can do.

    When Calumet they took over Zone VI they thru out all the research material for the times and meter. It also included how to do the test to make sure the timers were running correctly. The timer were made with timing chips one for normal time the others where matched to the film and paper curves these are fixed curves and can not be changed. At 68 degrees all three setting run the same as the temp goes up on the paper setting and the film setting the timer changes the time to keep the density build up the same as running at 68 degrees.

    Changing the pods will not effect the run time at higher temperatures. It will only change the start point which is 68 degrees.

    I wish I have all the research material from Kodak and the other film makers. Someone with the knowledge could make an app to do the same thing on a cell phone. The important part is knowing the log equation for the film and paper curves.
    Richard T Ritter
    www.lg4mat.net

  10. #10

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    Re: Calibrating a Zone VI compensating developer timer

    Quote Originally Posted by RichardRitter View Post
    . . . Changing the pods will not effect the run time at higher temperatures. It will only change the start point which is 68 degrees.
    Richard, What are the pods that you refer to? Thx.

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