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  1. #11
    m. dowdall's Avatar
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    Thanks guys

    The reflection density guide I have, has 12 steps from 0.0 to 1.75. So it looks like I'll pass on getting X-Rite's calibration tablets.

    Are the linearity values used just for checking the 'linearity' of the scale above and below the calibration high point? The manual doesn't mention linearity in the calibration steps.

    Michael

  2. #12

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    Hello Michael,

    I was wondering if you had any success using the Stouffer wedges. I just bought a model 810 and it has no calibration plates.

    I am assuming I should buy the calibrated reflection and transmission 21 step or 12 step wedges?

    Thanks,
    John

  3. #13
    m. dowdall's Avatar
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    John

    I've been using an uncalibrated Stouffer transmission step tablet. I checked it against a late sixties Macbeth densitometer and it's calibration transmission step tablet. The Stouffer step tablet is very close to the Macbeth one. So as far as I can tell the Stouffer works for transmission calibration.

    As for reflection calibration, the Kodak reflection density guide that I used is from the fifties. It's possible that it has faded some over the years. The values stated are linear but the readings are not. I've used the greater density as my calibration point and checked against the test prints made with the paper I use and the Stouffer tablet. Although I didn't plot them on a graph. The reflected values appear to fallow the appropriate curves for the papers different contrast grades. So the values for reflection are not set to a standard density. But all I need right now is to be able to measure the change in densities. In the future I’m going to get one of Stouffer’s reflection step tablets.

    Michael

  4. #14

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    Michael,

    Thanks for the information. I have a Stouffer 21 step transmission that Donald Miller was kind enough to measure and record the values for me. Looks like I should get the Reflection from Stouffer too.

    Regards,
    John

  5. #15

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    I have the 810 with reflective and transmission capability...(some do not have the reflective head). I have the Xrite reflective tablet and it is not as easy as taking one reading and transposing it to each of the channels. Each of the channels will have a different value for each of the three readings that are used to calibrate the instrument. Just wanted to mention this before someone goes crazy trying to figure why things aren't working as they should.

  6. #16
    m. dowdall's Avatar
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    Thanks for the heads up Donald. I only read the visual channel at the moment in reflective mode. The reflective step tablet I plan on getting from Stouffer is colour calibrated. I'm assuming that the transmisive step wedge is balanced for colour. I’ve checked it with an old Macbeth densitometer and it’s reads as balanced.

    Michael

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