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Thread: Calibrate a densitometer?

  1. #1

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    Calibrate a densitometer?

    Hi

    Is there a simple and easy way to calibrate a densitometer? Any suggestions?

    Thanks

  2. #2

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    Re: Calibrate a densitometer?

    Hi Matthew,

    The exact procedure depends on the model. But essentially, there are two steps to it:

    1. Set the zero point - take a reading with no film, just the light itself and set the scale to zero. If your model comes with separate color channels and a composite one, zero out each channel.

    2. Calibrate to a known standard - measure a previously calibrated sample and set the instrument to that value. Normally, it would be the "calibration chip" that originally came with the device, but if you don't have it, you can order a calibrated transmissive wedge from Stouffer and use the densest step for this.

    Recommended practice is to turn the densitometer on at least one hour prior to use (to let the light source filaments to heat up and stabilize) and to calibrate before each session.

    Hope this helps.

    Marko

  3. #3

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    Re: Calibrate a densitometer?

    Quote Originally Posted by Matthew Rolfe View Post
    Hi

    Is there a simple and easy way to calibrate a densitometer? Any suggestions?

    Thanks
    You really need the manufacturers calibration references for reflective and/or transmissive readings to ensure you get consistent readings and to know that your instrument is working properly.

    At the very least get a copy of the instruction manual and purchase a Stouffer's calibrated (reflection and/or transmission) step tablet with the proper density range required for calibrating your machine.

    Don Bryant

  4. #4
    ic-racer's Avatar
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    Re: Calibrate a densitometer?

    A generic calibrated step wedge is a little on the expensive side, but it will have an appropriate density strip that can be used for the "high density" calibration. On my unit it specifies using a density standard around 1.8 log d.

    Which densitometer do you have? If you don't have the manual, maybe someone can help you out.

  5. #5

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    Re: Calibrate a densitometer?

    Marko, Don and IC, thankyou for your responses.

    I don't have the instruction manual or the calibration chip so I am a bit stuck there. The make and model is;

    Melico PhotoLog B/W Transmission

    I will have a look for the manual on the internet. I will have a look at the step wedges, prices etc, I hadn't heard of them until you replied to my post, so thanks for bringing them to my attention.

  6. #6

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    Re: Calibrate a densitometer?

    WFIW, I am using Stouffer TP4x5-21C step wedge, which stands for Transmissive Projection 4x5 21-step Calibrated with the Eseco TRC-60D densitometer. Here's the link:

    http://www.stouffer.net/Productlist.htm

    The important part is to get the Calibrated version (a C version) rather than non-calibrated, even though it is a bit more expensive (but still very reasonable).

    I bought my densitometer on eBay for a song, but it came with no manual and no calibration chip. I tried buying the missing parts from Eseco first, but they didn't seem at all interested and at my insistence quoted a truly ridiculous price.

    Stouffer, on the other hand, was very reasonable and nice to deal with. I got the manual for free from another member, and it's been working fine ever since.

    Marko

  7. #7

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    Re: Calibrate a densitometer?

    Dear my friends,

    I have a GAM densitometer standard. (Reflection densitometer)

    Please share with where should I send the standard sample for re-certificate.

    I can be contacted by tkcheah@pioneerstd-ap.com

  8. #8
    ic-racer's Avatar
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    Re: Calibrate a densitometer?

    I'd just buy a new sample if you think yours is no longer correct.

  9. #9
    Peter De Smidt's Avatar
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    Re: Calibrate a densitometer?

    X-rite makes calibration plates for reflection densitometers. Another option would be to someone who has a good reflection densitometer, as well has the correct calibration plates, takes readings of your plates. You would then know the numbers that you'd need to enter into your densitometer to use your plates for the calibration routine.
    “You often feel tired, not because you've done too much, but because you've done too little of what sparks a light in you.”
    ― Alexander Den Heijer, Nothing You Don't Already Know

  10. #10

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    Post Re: Calibrate a densitometer?

    Dear Peter,
    I'm from service company. The densitometer belong to customer.
    They requested to do re-certification on the standard plate.

    I guess confirmation with a good densitometer may not acceptable as they was requested by the auditor to re-certify the standard sample.
    Do you know someone can do re-certification for this standard sample Click image for larger version. 

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    I get your idea, maybe look for X-rite to get a new calibration plate.

    Quote Originally Posted by Peter J. De Smidt View Post
    X-rite makes calibration plates for reflection densitometers. Another option would be to someone who has a good reflection densitometer, as well has the correct calibration plates, takes readings of your plates. You would then know the numbers that you'd need to enter into your densitometer to use your plates for the calibration routine.

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