Some reading on D65 vs. D50 on Cobalt's site ... so, it isn't like they aren't aware of D65's relevance ... so, why present the spectral response from D50 illuminant, instead of D65, when claiming how "inaccurate" different cameras are.
Shifting gears a bit ... so, am I to understand that basically Spectre ... is Cobalt doing for other cameras, an emulation of what Hassy is doing with HNCS (never mind the variance of D50 vs. D65 illuminants) to extract the most amount of spectral separation available to the specific camera.
This, then being different from Cobalt profiles where the intent is to emulate a series of different camera / film stock profiles.
@RustyBug I think the misunderstanding is simpler than it may appear.
Your red-light-on-a-green-object example is correct, but it does not describe how our sensor measurement is performed. We are not photographing coloured objects illuminated by a D50 lamp. The sensor is measured wavelength by wavelength with a monochromator, so the blue response is measured directly just like the green and red responses. No part of the spectrum is missing because D50 is “too warm”.
D50 is applied afterwards as a reference illuminant when calculating that particular score. Using D65 would change the weighting and could produce somewhat different results, so it may certainly be interesting as an additional benchmark. But it would not make the measurement more complete or intrinsically more correct: D50 and D65 are simply two different standard daylight distributions.
In short: D50 does not illuminate or limit the spectral scan. It is the reference used to interpret the already measured sensor response.
