Re: [APD] Coral Sun Lights

[Jerry Baker <jerry at bakerweb_biz>]

Wright Huntley wrote:
> In colorimetry it describes the APPEARANCE (i.e., color perception), and 
> in no way describes the spectrum or a real temperature. It simply is 
> supposed to say what the light looks like to a "standard observer."

The way I learned it, Kelvins always refers to a temperature. A 
theoretical black body heated to 6000°K will emit a very specific 
spectrum of light 
(http://hyperphysics.phy-astr.gsu.edu/hbase/bbrc.html). In colorimetry, 
a color can be said to be 6000K if it matches the appearance of a that 
black body. Therein lies the rub. We've switched from empirical 
measurement to subjective perception. The human eye is totally incapable 
of judging the spectral quality of light. We can't tell whether a light 
is simply yellow, or has a broad spectrum of wavelengths that taken 
altogether appear yellow. The problem for us in the hobby is we can't 
tell what a Kelvin rating on a light bulb refers to for certain. Does 
the manufacturer mean that this 6500K bulb nearly duplicates a 6500K 
black body spectral emission curve (like Iwasaki 6500K MH bulbs), or do 
they mean that the bulb only emits essentially one color that happens to 
appear to our eyes the same color as a 6500K black body?


-- 
Jerry Baker

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