Kodak Model 2 densitometer (X-rite 811) operation question

Discussion in 'Darkroom Equipment' started by tim_bessell, Apr 17, 2008.

  1. tim_bessell

    tim_bessell Member

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    Hi,

    I picked up a Kodak model 2 densitometer (X-rite 811) pretty cheap ($50USD). The read lamp was out. I soldered in a lamp from a Mag Lite and it works, well, it passes its self test and calibrates. The visual channel seems to work as expected, but the green channel always reads around 0.07. It also has some trouble reading very high densities over 3.07. I will have a new read lamp from X-rite tomorrow and hope it will improve the accuracy. As it is, I think it will work satisfactorily for B&W.

    Anyhow, my question concerning the correct operation is this. When using transmission mode, I lower the read head and the bottom opal lamp goes out. This seems to be the way it should work, since reading the calibration target verifies a good reading. Still, I would like to be sure.

    Can anyone verify this is the correct operation?

    Thank you so much!!!
     
  2. Otter

    Otter Member

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  3. tim_bessell

    tim_bessell Member

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    Thanks Otter, but I am not having any problems calibrating. Instead, I wish to know if the bottom lamp should go out when the read head is lowered to take a reading.
     
  4. Otter

    Otter Member

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  5. tim_bessell

    tim_bessell Member

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    Yes, I have both those documents, plus a calibration technique used for what appears to be a later model 811. I'm hoping someone with an 810/811 will jump in to tell me mine is working correctly. I guess I could give X-rite a call with my question.

    Thanks again.
     
  6. tim_bessell

    tim_bessell Member

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    Otter,
    You listed or started to list something from Kodak's site. Was that an error on your part or did you find something at Kodak. I could not find any info at Kodak for the Model 2 densitometer.
     
  7. Bob F.

    Bob F. Member

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    I have the 811. The bottom light goes out in TA and TM modes on mine.

    Cheers, Bob.
     
  8. jollyminter

    jollyminter Member

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    You can use pretty much any type of lamp to pass the calibration. Performing a calibration step does not mean your densitometer is working properly. Calibration means setting your device to a known state -- either right or wrong. There is a reason why some transmission densitometer cost significantly more than the others. The difference is accuracy and repeatability. A lamp must fire at approximately 2,856 degrees Kelvin to meet the ISO/CGAT standards. I doubt very much an off-the-shelf lamp can do this -- You can throw your accuracy out the window. Moreover, the visual filter on your instrument is probably deteriated (Wratten filter). A good transmission densitometer should read accurately between 5.0 density (0.0001% light transmission) to 6.0 density (0.00001% light transmission). There are three models that I know that reads properly in this range. They are: GretagMacbeth D200 II ($2,500.00), X-Rite 361 ($2,400.00) and Ihara T500 ($1,400.00). Good luck!
     
  9. epatsellis

    epatsellis Member

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    so, out of curiosity, with the typical b&w user measuring a density of under 2.00, is there a corollary to the Nyquist Theorom for denstitometers that I'm unaware of? Or is it only a valid test if it's calibrated traceable to NIST standards? Or would it be a good tool, regardless of what the actual reading is, if the relative measurments agree (over time as well) and allows the user to calibrate his exposure and processing to a personal standard (one a little more repeatable than "reading a newspaper through the densest parts of the negative"). Then again, it's your first post, I'm probably full of s#$t anyway.....



    erie
     
  10. tim_bessell

    tim_bessell Member

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    Bob,

    Thank you, that is the answer I was looking for.
     
  11. tim_bessell

    tim_bessell Member

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    I am sure that an off-the-shelf lamp is going to affect accuracy. I tried this just to be sure the unit was working before I spent $36.00 on the correct lamp from X-rite. We will see tomorrow when I get the right lamp.