THE LOW-DOWN ON
Widely used by lighting manufacturers, the
Color Rendering Index was devised by the CIE
(Commission Internationale de l’Eclairage)
during the 1960s to assess and quantify color
fidelity. It evaluates how a light source renders
eight standard color swatches, in comparison
to a perfect illuminant with the same color
temperature. How well the light renders each
color swatch is rated on a scale from 0 to 100,
and then the average is calculated to produce
the CRI number. Look at most lights sold to
photographers and you’ll find a CRI number
in the 90s, which in principle indicates
excellent color rendition.
But the devil is in the details. To begin
with, producing an average number can mask
important differences in the individual colors.
“Consider two hypothetical lights,” says Fiilex
optics engineer Sean Inaba. “One scores
0 on the first four samples and 100 on the
second four. The second light scores four 100s
followed by four 0s. These two lights would
be completely different from each other, but
both would have average CRI ratings of 50.”
CRI is a much more subtle measurement
than a single number; it’s an average across
multiple color measurements.
Another problem is that the eight colors,
named R1 through R8, are fairly easy to render.
“All the CRI score tells you is how well you
reproduce eight pastel colors,” says Cineo Chief
Technology Officer Chuck Edwards. Those hues
are not very relevant to many videomakers’ or
GEaR & TECHNIquEs FRaMEs PER sECOND
LEFT a ND OPPOsI TE: The Color Rendering Index was
originally designed around eight standard colors.
It has since expanded to encompass more colors
for greater accuracy.
BELOW: All LEDs advertise a CRI score, but you’re not always getting an apples-to-apples comparison.
CONTINuOus LIGHTs aND THEIR
can help you choose
the right light for
your video work.
BY aIMEE BaLDRIDGE
LEDs offer filmmakers and photographers working on combined still-plus-video
shoots a versatile, portable light source. However, after using LEDs, you may have
reviewed footage and found that your main character in a scene looks sickly. The light
on the subject’s face looked crisp and clean on location. Maybe you even checked its
Color Rendering Index (CRI) rating before you rented the light, to make sure it would
render colors accurately. Where did you go wrong?
Before you blame your grip or the rental house where you got the lights, it’s helpful
to take a deeper look at what that CRI means.
CRI numbers don’t tell the whole story about color rendition when it comes to LEDs.
Even your eyes can be fooled. To get the details on what CRI ratings can (and can’t)
tell you about an LED, and how to choose a light that will let you capture natural-looking skin tones, we talked to engineers at LED manufacturers Cineo and Fiilex.