The brave new world of CFL and LED lighting.

Incandescent is not dead, only the older versions. Look into the energy efficient versions which will continue to be manufactured.

CHEERS...Mathew

If you google (or your choice of search engine): Color Rendering Index, and Spectral Power Distribution for CFL / LED, you will see what your sensor or film is up against.
At least one company is actually using multiple color LEDs in their replacement recessed light units. That should give them a less spiky SPD along with a higher CRI.
I have started to change from CFL to LED in my home, mainly to be able to use dimmers again, and will try a simple straight lit color chart shot to see what that ends up looking like.

It is my understanding that there are no TRUE white LEDs currently in production. The ones that appear white are typically blue LEDs filtered through a yellow filter within the LED assembly. Thus, their spectra is still very peaky.

Jim M

White LEDS are not the same as Red + Blue + Green LEDs. All LEDs are essentially monochromatic (or at least they produce light in a fairly narrow spectral region).

LEDs generate light through a quantum process involving transitions between discrete energy levels. They are therefore intrinsically narrow band emitters. Not as narrow as a laser, but still pretty narrow.

You can't make a white LED by filtering. There are two ways to do it. You can mix red, green and blue leds of the correct intensity to give something that resembles white light. You can also use a phosphor which is excited by a deep blue/near UV LED and which then fluoresces over a broad (white) spectrum. Both look "white" but in fact may have a significantly different spectral distribution. The phosphor based "white" LEDs usually show a strong peak in the blue and/or near UV and a continuous band with a maximum around 550nm. The R+G+B "white" LEDs (which are uncommon) show red, green and blue peaks with deep dips between them.

Some colors can look quite different under the two types of "white" LED illumination.

When shooting under LED lights, I'd do a custom white balance if I had only JPEGs, but I'd always shoot RAW if that was available.

It is my understanding that there are no TRUE white LEDs currently in production. The ones that appear white are typically blue LEDs filtered through a yellow filter within the LED assembly. Thus, their spectra is still very peaky.

Actually all white LEDs use z a blue LED that is coverd by phosphor. The phosphor converts the blue to multiple colors needed to get white. A yellow filter over a blue LED won't get you whilte light. Cheap white LEDs use very little or low quality phosphor which allows a lot of blue through. Quality LEDs use a much better phosphor allowing for a more uniform white "less spiky" in your words. CFL lights do the same but use UV light that is converted by phosphor to white.

When buying a LED or CFL light you want to look at:

1. color rendering index (0-100 with 100 being about what a tungstan bulb does), Most good LEDs and CFLs have a CRI of 85.
2. Color temperature, 2700 is a yellowish white commonly refered to as soft white while 3000 is often refered to as bright. Anything higher than 3000 will have a lot of blue
3. LUmens. The the brightnes of the bulb. Most packages will say equivent to 40W or 60W etc. Don't trust the wattage equivelent. compare the lumens of the bulbs.

I have had very good luck with LEDs from Fiet electric or Sylvania. both are available at Lowes home improvement stores.

"We have a lot of artwork hanging in the house, and I want it to look good (color-rich), while at the same time shaving our energy budget ."

The expense might outweigh the energy saved depending on how critical you are. An alternative might be to use (conventional) directional spot lights to selectively light the artwork.

The Smithsonian Institute has a slideshow presentation on their transition to energy efficient lighting which might answer many of your questions:
[Link]

Any neutral-ish light be it CFL, LED or tungsten (Solux 4700K 50 watt) is going to deliver good enough color rendering for viewing artwork. The only way to see the holes in the spectra among these type of lights is by comparing them side by side.

The human visual system is very good at adapting and filling in these spectral reflectance holes as long as they don't have some other light with a different spectra staining the results.

I haven't yet found an LED that is affordable and delivers good color rendering. The only one I do have is a military grade flashlight JetBeam II using a Cree Q5 LED filament. I chose this one because online reviews found it to be the most neutral looking which it is, but renders flesh tones and most other warm hues ashen with a slight cyan cast with cadmium yellows turning a bit green.

Thanks, guys! You've given me some great information. From what I can tell after reading a few articles, a spectrum can be somewhat spikey and still have a good CRI, so long as it doesn't have outright "holes" in the spectrum. Tim, what you say about the visual system filling in the gaps in color information seems to be spot-on. If this is true, then I might be able to throw that essential lick of full spectrum lighting onto the artwork (Michael's suggestion) with small, lower-wattage tungsten spots, which would work in conjunction with the CFL or LED main lighting. Of course I'd have to be careful about mixing color temperature.

Although there are still incandescent lights available, they will continue to disappear, and they probably should. I will miss them dearly, but I cannot personally justify their use, with global warming and with wars being fought essentially over energy. In our household, we continue to look for ways to shave our energy usage however possible. In fact we will be taking the next bold step forward very soon with a rooftop of solar panels. We look forward to making ourselves energy-neutral. We don't want another young person to die to feed our energy needs. Of course in all this mix, I do have to carve out an energy budget for artwork, because I will always feel that artwork is a necessity. We'll just feed that budget with solar energy. ;-)

One thing I will be watching in the years to come is how the longevity of the color spectrum compares between CFL and LED. I know that white LEDs don't die, so much as fade away. Eventually the phosphors deteriorate, such that the longer wavelengths aren't produced. Thus, they get dimmer and bluer, until they are discarded because of their poor light quality. And of course fluorescents eventually die when their trace amounts of mercury (yikes!) eventually gets absorbed into the glass. At that point they just flicker and look miserable. I suspect high quality fluorescents will prove to be the more color stable solution, eventually supplanting incandescents in color critical applications, despite their higher energy usage than LED.

Anyway, thanks for getting me jump-started on this issue! :-)

Sarah, good to know you're wanting to do the right thing and save on energy. I have a similar mindset. However, I have developed an affinity for photographing under regular 100 watt GE Soft White bulbs due to the way my camera's "Tungsten" WB preset renders white with a pleasing off white creamy hue.

If you're concerned about fluorescent's longevity with regard to aging phosphors affecting color rendering, that GE Sunshine shot is from a T8 tube that's been on in my home going on about 5 years at 12 hours a day, everyday. With that length of time I can't tell if the phosphors have deteriorated. Colors still look good enough for reasonable screen to print color matching.