Throwing light on the subject

[unixronin]

I took down the two tacky fake oil lamps on either side of our kitchen window yesterday (they didn't really throw a lot of light anyway), and replaced them with overhead track lights throwing lots of good light down on the countertop where I need it.  As it happens, the two CFL bulbs I re-used from the old lamps were 3500K "bright white" bulbs, while the four new ones I installed were the default "soft white", simply because they're still a lot cheaper.

The difference is really very visible.  You look up at the lights, and the two 3500K bulbs are white, and the other four are ... sort of dingy yellow.

So here's the thing.  Now that we're finally moving away from incandescent bulbs, we don't have to settle for "soft white" any more.  It does not cost significantly more to line a CFL bulb with a 3500K phosphor than a 2700K phosphor.

So why is it that 95% of the CFL bulbs on the shelf are still that "soft white" crap, and the few 3500K bulbs cost five to eight times as much?  It's not "soft", it's DIM.  Nothing looks clean under that light.  Things look grubby and stained even when they're not.  Why should we have to continue to live with the visual limitations of an obsolescent lighting technology?

So anyway, the next time I'm by the hardware store, hang the extra $6 per bulb, I'm picking up four more 23W 3500K bulbs.  I have to work under that light, and I'm going to have it bright and white, dammit, because I want to be able to see properly what I'm doing.  It's the same reason I have 32W 5000K T8 tubes¹ in the shoplight over my workbench, and a 30W 5000K CFL hanging directly over my desk.

We don't have to settle for the poor visual quality of "soft white" dingy yellow any more, and I'm not going to.

[1]  T8 tubes are smaller diameter and more efficient than the old T12 fluorescent tubes.  A 48-inch, 5000K, 32W RE80 T8 lamp has a lamp efficacy of 92 lumens per watt, and a color rendering index of 86.  By comparison, a typical 48-inch "cool white" (4200K) 34W T12 lamp has a lamp efficacy of 78 lm/W and a CRI of 60; a "warm white" lamp has a marginally higher efficacy of 79.4 lm/W, but a CRI of only 53.  A 5000K 40W "full spectrum" T12 musters a CRI of 90, but manages only about 61 lm/W; a 5600K T12 pushes the CRI to 92, but at a relatively dismal 55 lm/W.  (Theoretically, even an incandescent bulb can achieve 52 lm/W, but that's at the melting point of the tungsten filament.  35 lm/W is a more realistic figure.) The newer T5 tubes are even more efficient; a 35W RE80 46" T5 tube can muster as high as 104 lm/W with a CRI of 85.  (T5 lamps can even be dimmable.)

Comments

[metahacker.livejournal.com]

Heh. And here I was just complaining how blue and glarey most of the CFLs we have are. O tempora, o mores...

[unixronin.livejournal.com]

The 5000K "daylight" bulb over my desk and the 5000K T8 tubes are a touch on the bluish side, yeah. But I don't have a problem with that. (Actually, I'm planning on tearing out the two existing T12 fittings in the workshop and replacing them with more T8 fittings. It's pretty hard to have too much, or too good, light in a workshop area.) The 3500K bulbs in the kitchen are just white to me, without any discernible color cast at all (though the first generation of 3500K bulbs I tried, two years ago, had a distinct — and rather odd — pinkish tinge).

[tomatoe333.livejournal.com]

Interestingly, once you've worked for a while under a 5000K or so lamps, you start to get used to it, and the "normal" lamps look too yellow and soft.

I have a 5000K "daylight" CF desk lamp that I use near my computer, and not only is it a better light to look at my photographic prints with, it helped a lot with my seasonal affective disorder this past winter.

[metahacker.livejournal.com]

Definitely a factor. I do like having a mix of colors for when I'm painting miniatures, for example, but strong light is essential in the winter. And hard to find. But blue-ish eventually actually hurts my eyes.

What I really want is the "LIGHT GUN" producing 100,000 lumens lux over a large area, that follows me from room to room...

[danjite.livejournal.com]

I thought CFLs were already facing obsolescence in the face of LED and OLED?

I mean, of course, in the decade time frame.

[unixronin.livejournal.com]

Not yet. They're getting better, but they have a long way to go yet. There are LED replacement bulbs on the market, but they're usually ten times (or more) the cost per lumen of CFLs, and generally only available in comparatively low light outputs. You can buy a commercial LED "bulb" that replaces a 40W bulb, for example ... for about $120. But, realistically ... does anyone actually even use 40W bulbs, other than five or six at a time in a chandelier?

At present, there's two problems with LED lighting. The first is heat dissipation. The second, and the part that really makes it hard to retrofit useful LED lighting into a building wired for incandescent light, is that the "a few big emitters" model of incandescent/fluorescent/CFL/metal-halide lighting really doesn't work well with LEDs. Part of this is that you can't build very-high-output LEDs without running into the heat dissipation problem mentioned above. So far, about the highest-output single LED emitter is the Luxeon Star 5, a nominal-5W LED with an output around 150 lumens. 30 lm/W is down in the incandescent range for luminous efficacy, but if they drive them any harder, overheating dramatically shortens the life of the LED. (At that, Luxeon-based flashlights are generally constructed to use the entire flashlight body as a heatsink. I have a 140-lumen Inova X0, and after about five to ten minutes of operation the entire flashlight starts to get noticeably warm.)

LEDs work much better when you can use either a large number of small emitters distributed over an area, or a large panel with an array of small emitters. They're great for automotive turn/brake/tail lights, and some companies are even trying to use LED arrays for automotive headlights, but for general home/office lighting they really aren't very suitable. There are other illumination technologies under development that look more promising, but they're still further off down the R&D pipeline.

[elegantelbow.livejournal.com]

Most consumers prefer the "soft white" lights and find the cold daylight colored lights to be too blue and too harsh for general lighting.

I've got a lamp right next to me with one bulb "warm white" and one "cool daylight". I'm amazed at the difference in color, but I think I prefer the warm white for diffused light and the cool daylight for task lighting.