I have a Sekonic C700 spectrometer. I notice that when I makes a measurement even of a colored test card illuminated by an incandescent light, it still looks like the normal tungsten curve:
It looks like the upper histogram in the picture above. If I test a blue or a red card, it looks virtually the same. There are only slight differences. I assume this is because the spectrometer is not "focusing" on the card, so it sees the ambient light, not the light coming from the card.
But I don't really understand this because I am holding the meter right up to the card, so the only light it should be getting should be light coming from the card. Therefore, I would have expected the red or blue color to be more clearly shown, but this is not happening. Why not?