| The CRI (color
render index) rating of light sources, is an old standard developed by the
International Commission on Illumination (CIE) in the 50's. It is a
relative index which compares the relative color reproduction ability of
one light source to another. The maximum value of 100 is given to Tungsten
light sources, therefore all other light sources including sunlight will
have values less than 100. This was an important reference for film
photography because tungsten balanced film rendered perfectly in
tungsten light and color shifted for almost all other light sources
that have lower CRI values.
The CRI light valuing method is mostly irrelevant to video cameras because
of "white balance" compensation for color temperature. In reality tungsten
light has an abundance of red and infrared (heat) and is relatively weak
in the blue part of the spectrum. HMI light sources produce a visible
light spectrum similar to sun light, yet when compared to Tungsten light
they have a lower CRI.
Conclusion: We include CRI ratings in
our product descriptions because some of our customers are film users. We
are anxiously waiting for the CIE to develop a better index that address
the many light generation technologies present today that are far better
than Tungsten sources.
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