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To: KarlInOhio
A friend put in a set of 5 6500 Kelvin daylight CFLs in his dining room. They are painfully bright.

Luminosity (in candelas or foot-candles), power consumption (wattage), and color (Kelvin number) are all separate concepts.

The color of traditional incandescent lighting is about 3300 Kelvin; halogen lamps at full power are more like 3800. The hottest halogen Osram and Sylvania Silverstar headlight bulbs are right at 4100K, just below the 4200K lower end of the high-intensity discharge (Sylvania's name: Xenarc) arc-type lamps, which go up beyond 10000K (violet and ultra-violet).

Those dining-room CFL's are supposedly "daylight" lamps and probably totally inappropriate for dining. A morgue would be more like it.

Then there's the problem of steadiness of the light source. Halogen bulbs on AC current and fluorescents tend to flicker invisibly at 50Hz or 60Hz, which causes eyestrain as the iris tries to follow the flickers and adjust. We're unaware of this losing battle, until we develop eyestrain, fatigue, and presbyopia.

I'm not sure how LED lamps perform on AC house power. I suspect they'd produce the same eyestrain as halogens.

The very best reading light is halogen bulbs on straight DC current. Incandescents are a good compromise, since their tungsten filaments heat and cool more slowly than halogen filaments, suppressing the flicker effect. My den uses recessed floodlights and spots (the spots look better); I'm stockpiling them. Ozero can sue me.

64 posted on 01/21/2011 9:51:03 PM PST by lentulusgracchus (Concealed carry is a pro-life position.)
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To: lentulusgracchus
Halogen bulbs on AC current and fluorescents tend to flicker invisibly at 50Hz or 60Hz, which causes eyestrain as the iris tries to follow the flickers and adjust.

Obviously you have NO idea how flourescent bulbs operate. Go google and read the description of the operation of the ballast. You will see that they DO NOT have a 60hz component, it is more like 40Khz!

69 posted on 01/22/2011 12:37:39 PM PST by SeeSac
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To: lentulusgracchus
The color of traditional incandescent lighting is about 3300 Kelvin; halogen lamps at full power are more like 3800. The hottest halogen Osram and Sylvania Silverstar headlight bulbs are right at 4100K, just below the 4200K lower end of the high-intensity discharge (Sylvania's name: Xenarc) arc-type lamps, which go up beyond 10000K (violet and ultra-violet).

Typical halogen lamps are about 3000k. I don't understand why you say 4100k is hotter?

70 posted on 01/22/2011 12:47:57 PM PST by SeeSac
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