color problem

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john37

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I have a question regarding Kelvin temperature and CRI I was hoping someone could help me out on.
I have a project that all the lamps were installed using 4100K temp but the CRI's are different from the 2x2's and cove strip lights. The cove T-5HO strips appear to be "white" but the 2x2's T-8 lamps appear to be more yellowish. Being that the CRI's are different would this make a difference in the color "appearance" of the lamps itself? I know the higher the CRI is better for color rendition but I thought the lamp temperature dictated the color of the lamps? The color difference is really noticable....
Any help would be appreciated. Thanks.
 
john37 said:
I have a question regarding Kelvin temperature and CRI I was hoping someone could help me out on.
I have a project that all the lamps were installed using 4100K temp but the CRI's are different from the 2x2's and cove strip lights. The cove T-5HO strips appear to be "white" but the 2x2's T-8 lamps appear to be more yellowish. Being that the CRI's are different would this make a difference in the color "appearance" of the lamps itself? I know the higher the CRI is better for color rendition but I thought the lamp temperature dictated the color of the lamps? The color difference is really noticable....
Any help would be appreciated. Thanks.
Click to expand...
Color temperature is more precise for incandescents. The incandescents generally have a smooth continuous spectrum. For a fluorescent, the energy spread across the spectrum may be different and two lamps with the same CCT may appear different in color. CCT and CRI are two different animals.

See if this helps:
http://www.gelighting.com/na/busine...ources/learn_about_light/color_specifying.htm

Pay attention to the discussion on the black body locus vs the correlated color temperature (CCT)
 
The temperature of the lamps can affect the color also. (By temperature, I mean the normal definition of temperature - how hot or cold the room is, or how hot or cold the lamps are.) I've seen projects where all the lights that have diffusers next to them look like they have a different color lamp.

And since T5 lamps like to operate at a different temperature than T8 (they like to run hotter), I doubt you will ever get the T5 lamps to look exactly the same as the T8's no matter what type of lamp you use.

Steve
 
A 4100K T8 is very close to the white of a 4100K T5, but not perfect. The CRI doesn't make the lamp look different, what is under the lamp looks different. The lamp temp determines the color of the lamp.
 
Color is determined by the (visible) spectrum of emitted radiation, the relative strengths of red, orange, yellow, green, blue, violet. White is all colors together.

Above some minimum temp, hotter things are brighter. A carbon arc is at 10,000 F, and I guess it appears white.

I'd think different substances at the same high temp could have way different spectrums (mercury vapor, sodium vapor, projection lamps, arc lights).

I'll look it up, but I think the connection between the emitted spectrum and the stated temp is complicated.
 
You'll need your hip boots to wade through this, but they do talk about incandescents and flourescents.

http://en.wikipedia.org/wiki/Color_temperature

A black body absorbs all light; I still don't understand why it can also be an efficient emitter.
More research needed!
How 'bout a research grant?
 
langjahr@comcast.net said:
A black body absorbs all light; I still don't understand why it can also be an efficient emitter.
Click to expand...

It's a reciprocal thing - much like the pattern of radiation of a transmitting antenna is exactly the same as its receive pattern. If a material could absorb a higher percentage of incident radiation than it radiates, call the thermodynamic police!
 
It's a reciprocal thing

It's a reciprocal thing

I've called them several times over the years, and it always turned out to be a false alarm.
How am I ever going to get rich if I have to obey those pesky laws of physics?
 
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