[opendtv] Re: News: Will LEDs Light Your Productions?




Dear Alan,

> And I'm just fine with the theory, I've been investigating and using it
for
> 25 years, and make a reasonable living in teaching it to others. I've
been
> trying to teach it to you for some years now, but I don't seem to be
having
> much success :-)

I know that...  I was just teasing you to try to get you to be
a little bit more accurate in what you say or how you say it.
I was afraid that you meant to say that spiky spectra are okay.

I am happy that this is not the case, that we agree that a white
lamp must have a fairly wide spectrum. Not entirely flat, but
good enough that it won't interfere with aspects of the camera
that would make it see a different picture than what the eye sees.
It also depends on how sharp the reflection spectrum of coloured
surfaces is. For a grey/white surface it would not matter at all.

Interesting what you say about monochromatic primaries, that they
would reveal differences in colour perception between observers.
I suppose that the same could be said of cameras then, if you fed
them with monochromatic light sources ? They would become super-
critical ? Fortunately this is not a realistic use case.

About these LEDs: theoretically an LED could be sold as a "white
lamp" if it produced only a line of yellow and a line of blue on
opposite sides of a white point. If you shine it directly into
your eye then you will certainly see white light. But it is still
useless as an illuminator for surface colours. Who will guarantee
me that these LEDs that this thread is about have anywhere near a
flat spectrum ? I would like to see some evidence for that...

Best regards,
-- Jeroen

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