Andrew Rodney's excellent Youtube video has encouraged me to use camera profiling. I had thought that there was little point as the light varies so much from hour to hour and season to season; but Andrew makes a compelling case that it's the general shape of the light spectrum that we need to look at, that the daylight spectrum varies little between dawn,noon and dusk or summer, winter; and that what we are doing is essentially calibrating our individual camera sensors to a generalized lighting condition.
I've played around a little with camera profiling and what certainly seems to be true is that I get more color fidelity if I use an ACR profile created using DNG Profiler or ColorChecker Passport rather than the Adobe Standard profile, irrespective of the outside light. That makes sense to me because the profile I generate is for my camera whereas the Adobe profile is a generic (average?) one.
However, I'm not so convinced about the time of day. Here is a plot of the spectra at my house yesterday: mid-day cloudy, early evening with a blue sky, and sunset with a slight haze:
It seems to me that the early evening, blue sky has significantly less green and red, whereas the sunset slight haze has a dip in the yellows and a peak in the red, and the mid-day cloudy is overall flatter than the other two (nearer D50).
The thing that's a bit concerning in terms of camera calibration is that there was only about 20 minutes between the Early Evening Blue Sky and the Sunset Slight Haze - and there is a big peak in the reds in the latter case (together with a significant drop in luminance). I can't see how only adjusting the white balance of an image would compensate for this ... but, hopefully I'm wrong.
Advice welcome!
Robert