Consistency using spectrometer with ArgyllCMS

Hello,

I recently purchased an Xrite ColorMunki Photo, and have set it up to be used with ArgyllCMS and Osram Color Calculator. The TM-30 reports I’ve generated seem to be in range of what I could expect, but I wanted to ask how people using these tools ensure consistency/accuracy? I have my spectrometer placed on the floor beside my pc under my desk, and when I run a spotread the only light source on in the room is my monitor. Does that even matter considering ArgyllCMS requires a calibration before use? Any advice would be greatly appreciated!

Here are three reports of my Zebralight SC65C HI; levels L1, M1, H1.



Repeatability is easy to test, as for accuracy, can’t really know for sure without a fully known reference light. There is a partially known reference : an incandescent bulb (or any incandenscence, e.g. a candle), of known duv of 0 and CRI of 100. If the spectrometer is close to that it’s already a good indication of accuracy.

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I thought the colormunki photo does calibration via an internal light source, which is why the sensor is rotated and unexposed to ambient light during calibration. I could be entirely wrong about the internal light source, but I think I am at least correct that the sensor is not exposed to ambient light during calibration.

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Thank you for this, I’ve seen data of a candle using a spectrometer (one of your replies somewhere lol). I didn’t think to use that myself to check accuracy. I’ll test a candle tonight and take a look at the result. I’ll upload the report here for fun :grin:.

Got home and did a candle test, looks pretty good overall. I’m still curious as to accuracy, but I’m happy it seems to be in working order.

Looking at the colormunki photo the sensor does get shielded when set to calibrate. Thanks for pointing that out.

This is what I got from a birthday candle using the same equipment:

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Thanks for checking, honestly I’ve been having fun testing anything and everything with this spectrometer.

It would be interesting to compare tests from a nearly identical source, such as the same model of Maglite bulb powered at the same voltage, with the sensors placed the same distance from the source.

I’d be interested to see that, i did find an old maglite in a closet the other day. Or a incandescent AAA maglite maybe?

Or are you suggesting to use a maglite bulb connected directly to a fixed power source, not powered by a battery in host?

Yes. A steady fixed voltage is necessary for a reference test because the CCT will vary with the operating voltage of the bulb.

I’ve got benchtop power supplies, and various kinds of maglite bulbs. I could just test all of them at their rated voltage. Larger maglites have a spare bulb in the tailcap, so using the spare would avoid runtime hours having an effect on the results.