|
What is Color Temperature?
The color temperature of a lamp (bulb) describes how
the light appears when the human eye looks directly
at the illuminated bulb. Color temperature is measured
by a unit called the Kelvin (K). The Kelvin thermodynamic temperature scale is defined so that absolute zero is 0 kelvins (K). (Note: The Celsius and Fahrenheit scales are defined so that absolute zero is −273.15 °C or −459.67 °F). Imagine heating
a bar of steel and observing the color of the bar at
increasing temperatures. At some point the bar will
appear to glow a dull red. As heat is added, the dull
red turns to yellow, then to white, then to bluish white,
finally to blue.
A light bulb that produces light perceived as yellowish
white will have a color temperature of around 2700K.
As the color temperature increases to 3000K - 3500K,
the color of the light appears less yellow and more
white. When the color temperature is 5000K or higher
the light produced appears bluish white. The color temperature
of daylight varies, but is often in the 5000K to 7000K
range.
When the desired lighting effect is "warm",
use light sources in the 2700K - 2800K range. Most common
incandescent light bulbs will produce light in this
color temperature range. An exception is the incandescent
light bulb with a neodymium coating. The neodymium filters
out the yellow and red wavelengths of the visible spectrum
leaving predominately blue wavelengths. So even though
neodymium light bulbs have a 2800K color temperature,
the light they produce appears to be bluer - similar
to daylight and to other light bulbs that product light
with color temperatures in the 5000K or higher range.
When the desired effect is neutral or white, use light
sources in the 3000K - 3500K range. For a slightly bluer
effect use 4000K.
What Color Temperature Simulates Daylight?
To give the perception of daylight (bluish white light),
use light sources with a color temperature of 5000K
or higher. Above are links to light bulbs available
from Topbulb with a color temperature of 5000K or higher.
It is important to note that color temperature is not
the same as color rendering. The color temperature of
a light source does not describe or predict the ability
of that light source to render color accurately. For
more on this topic, go to the explanation of color
rendering. |
