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Re: Algae and Incandescent Lighting



I wrote:
The color rendering index (CRI) of most low light temperature lamps is not
good compared to lamps in the 5000-6500K range lamps. So a mix of both is
the solution that is frequently used.

David wrote:
It's my understanding that incandescent lamps, despite having a
significantly lower light temp than, say, cool-white NOs, have CRI at or
near 100. So if people opt for fluorescents over incandescents, or if they
add in some  fluorescents to a previously incandescent-only fixture, then
it's for some other reason than CRI (e.g. operating cost, cooler tanks,
<esthetic>, superstition, whatever's-on-hand, etc.). I've read that we
should try and think of CRI and light temp K as uncorrelated. <my emphasis>

but David also wrote:
On a personal note, I'm a little saddened to think 6700K CFs, whose
spectrum I prefer on <esthetic> grounds, may end up giving algae a better
chance in life. <my emphasis>

and then Ivo wrote:
(ii) color temperature - incandescents have a too low color temperature, so
even with a CRI of 100 the resulting colors that we
see look <unnatural> when compared with the same colors viewed under
sunlight. <my emphasis>

> I've read that we should try and think of CRI and light temp K as
uncorrelated.

They are uncorrelated.
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So now I'm confuzzled. I thought CRI was an attempt to quantify an esthetic
parameter of the light source. If the CRI is at or near 100, but you still
think the colors are not esthetic (David), or are unnatural (Ivo), then why
bother with CRI at all? I guess what I was saying was that the lower Kelvin
lamps that the plants prefer are not compatible with the higher Kelvin that
our eyes prefer. Which is what I thought CRI is supposed to
measure...grumble.

Tom