Starstruck8
Brilliant_Rock
- Joined
- May 13, 2021
- Messages
- 753
Kenny: You have finally persuaded me to sign up after years of lurking.
I have started this new thread because I don’t want to further derail Voodoo Child’s.
Voodoo Child, LD and the author of the note LD linked to all note that daylight balanced photos of alexandrite under incandescent light are truer to what they see than correctly balanced ones. I can add that for my blue-to-red colour change garnet, correctly balanced photos taken under incandescent light look about right, but correctly balanced photos taken in daylight are way off – the stone looks blue, the photos turn out purplish red. (Before you ask: I shot raw, balanced from a white reference, and made sure that no channel was maxed out.) This is not ‘faith’ or ‘religion’: it’s what I have seen with my own eyes.
There is a scientific explanation. Ordinary cameras are not ‘tristimulus colorimeters’. The spectral sensitivity curves of their photosites do not match those of our cone cells. (Strictly: they don’t meet the Luther-Ives condition.) So they cannot, even in principle, even with correct white balance, capture colour exactly as our eyes see it. In practice, they do an adequate job for most everyday subjects. But they can fail badly for gemstones, which may have strong narrow transmission and absorption bands with sharp fall-offs.
The moral: You may regard any colour adjustment other than correct white balancing as ‘cheating’ or ‘photographic blasphemy’. But with coloured stones, it is sometimes the only way to make photos look like what we see. To be sure, if you accept that doctoring may be necessary, you have to take people’s word that the doctored photos reflect what they see. Such is life.
I urge you to get hold of an alexandrite or colour-change garnet and photograph it for yourself. It’s quite fascinating – what you see isn’t what you get.
I have started this new thread because I don’t want to further derail Voodoo Child’s.
Voodoo Child, LD and the author of the note LD linked to all note that daylight balanced photos of alexandrite under incandescent light are truer to what they see than correctly balanced ones. I can add that for my blue-to-red colour change garnet, correctly balanced photos taken under incandescent light look about right, but correctly balanced photos taken in daylight are way off – the stone looks blue, the photos turn out purplish red. (Before you ask: I shot raw, balanced from a white reference, and made sure that no channel was maxed out.) This is not ‘faith’ or ‘religion’: it’s what I have seen with my own eyes.
There is a scientific explanation. Ordinary cameras are not ‘tristimulus colorimeters’. The spectral sensitivity curves of their photosites do not match those of our cone cells. (Strictly: they don’t meet the Luther-Ives condition.) So they cannot, even in principle, even with correct white balance, capture colour exactly as our eyes see it. In practice, they do an adequate job for most everyday subjects. But they can fail badly for gemstones, which may have strong narrow transmission and absorption bands with sharp fall-offs.
The moral: You may regard any colour adjustment other than correct white balancing as ‘cheating’ or ‘photographic blasphemy’. But with coloured stones, it is sometimes the only way to make photos look like what we see. To be sure, if you accept that doctoring may be necessary, you have to take people’s word that the doctored photos reflect what they see. Such is life.
I urge you to get hold of an alexandrite or colour-change garnet and photograph it for yourself. It’s quite fascinating – what you see isn’t what you get.
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