copy of my reply to other discussions...( I know this is against rules etc... but....)
Sent an email to QPcard to ask about their product referring to discussion on this site.
specifically I asked about capturing the right data for original artwork as compared to photos...
below is their second email... I will be buying one of their charts as I find passport colours too bright/gaudy in colours.. ( or is it me?)
Lars already wrote a few things, but I though that some things were maybe still a bit unclear.
1) 203 is most probably better for you, since the 202 is slightly more sensitive to specular reflections. The 202 IS larger and easier to incorporate in larger works though, so as long as you have a reasonable control over lighting angles (and I guess you do, since you're into art-repro) 202 should not be a problem in your case.
2) The exposure has to meet those requirements:
-no colors overexposed in the raw file. When you open a file, no "blinkies" should be seen in the raw converter
-not severely underexposed. If you can add more than +2Ev exposure without getting blowing the "white" patch, you've probably lost some profiling accuracy.
There's a +/- 1Ev "window" of optimal exposure for the software to work with, and generally this is not very hard to satisfy. It WORKS with -3Ev exposure too, but the result is less accurate.
For your type of work (art-repro, of which I have done my fair bit...) often the exposure curve tends to mess things up a lot. The calibration gives you "accurate color" when everything is set to "zero", i.e no added contrast, no s-curve in the shadows and so on. When you add those things in, you oversaturate the midtones - where the exposure curve of a normal S-shaped type is at its' steepest.
steep curve - midtones - saturation increases
shallow curve - shadows and highlights - saturation decreases
When the RGB values has "one leg in the highlights and one leg in the midtones" you get a hue shift.
All of those things has to be adjusted for with human interaction, since there's no "perfect" exposure curve for any given type of art. But if you know the effect things have on your colors, they are quite easy to correct for. And when you have one good "oil, with semi-matte surface structure" setup, then this works for most pieces of similar qualities, regardless of artwork color constitution.
Feel free to as any more questions you might have, I will help you with setup of the calibration (via email of course...) :-) if you want some hints.
Greetings from Sweden
Senior developer, QPcard.com