Spectral emissions from modern light sources (more graphs added)

color

#41

The CRI of a light source does not indicate the apparent color of the light source; that information is given by the correlated color temperature (CCT). The CRI is determined by the light source’s spectrum. An incandescent lamp has a continuous spectrum, a fluorescent lamp has a discrete line spectrum; the incandescent lamp has the higher CRI.

CIE Ra’s ability to predict color appearance has been criticized in favor of measures based on color appearance models, such as CIECAM02 and for daylight simulators, the CIE Metamerism Index.[3] CRI is not a good indicator for use in visual assessment, especially for sources below 5000 kelvin (K).[4][5] A newer version of the CRI, R96, has been developed, but it has not replaced the better-known Ra general color rendering index.[6]

Source: https://en.wikipedia.org/wiki/Color_rendering_index


(Graeme W. Gill) #42

The latest proposed standard seems to be gaining a bit more support:
IES TM-30-15


#43

I don’t really notice the CRI, etc., markings on the specialty bulbs in the local big box stores. Does it depend on the country and / or manufacturer? Or maybe I need to go to a specialty store.


#44

Do a web search for High CRI.
In ordinary stores, you will probably find LEDs with Ra = 90.
Look for “filament” LEDs. The last two types I have measured
have an Ra of 92.4 (the R9 value is just 67.2, though, but still),
TLCI = 89.8 (not bad!) and CCT=2727K.

Great fun!

They look like this:
9615531704350


#45

Lost half the readership: you better define those terms. :wink:


#46

I am working on it. Started with a single page.
Wasn’t sufficient. Will take time. Patience, please.

In short: R9 is a dark red patch, which is
very tricky to reproduce. A TLCI in the 90s is
good; 89.8 is close enough. TLCI is what
television camera men talk about.


(Ted Cousins) #48

Excellent series - well done. I remember making a spectroscope (slit and diffraction grating) just because a camera was giving me brown instead of red under a compact fluorescent lamp.

If I had known a ColorMunki could do it, I would have bought one.

Thanks …