Index (CRI) A key performance characteristic, color rendering, is the
ability of the light source to represent colors in objects. The relative measure of this
ability is color rendering index or CRI which rates the light sources on a scale of 0 to
The higher the CRI, the more vibrant or close to natural the
colors of objects appear. Natural daylight has been assigned a CRI of 100 at a Kelvin
temperature of between 5000-7500K. The Spectralite performs at 90 CRI which produces
excellent color rendition when color matching is critical.
Color Temperature(Kelvin), Color temperature or chromaticity
refers to the color appearance of the light that comes from a light source. Also referred
to as Correlated Color Temperature (CTT), the apparent color of light source is measured
in Kelvin or "K".
Imagining a piece of iron (a horseshoe, for instance) in a fire
can help you visualize color temperature in lamp types designated as "warm" or
"cool". At first the iron becomes "red-hot". Red is the color of light
be generated by the metal at a certain temperature. Continuing to heat the metal makes it
"white-hot", and heating it further would cause it to become
"blue-hot" (like flash bulbs or stars).
In describing color temperatures a low color temperature
corresponds to a "warm" or a red yellow appearance like incandescent lamps at
2700 Kelvin. "Cool" light comes from light sources like cool white fluorescent
lamps operating at 4100 Kelvin. The higher the Kelvin temperature, the whiter and then the
bluer the light. In the case of the Spectralite at 5900 Kelvin this produces a color on
the blue spectrum very close to natural daylight.
Lumen is the unit
that expresses the total quantity of light given off by a source, regardless of direction.
A lumen is defined as the amount of light falling on a surface of one square foot, every
point which is one foot away from a source of one candlepower. A uniform source of one
candlepower placed in a sphere emits 12.57 lumens.