Reducing power consumption is a worthwhile goal. But before telling people what light sources they can and cannot use, we should consider the effect those light sources have on human visual development. (“Think of the children!”) I’m surprised I haven’t heard anyone mention the spectral power distributions (SPDs) of light sources in this debate.
You can compare SPDs of different light sources at The National Gallery's SPD Curves web site. Select “Update selection” to choose the data series to chart. You can overlay multiple SPD curves for comparison. The curves are all normalized sensibly.
Among the data sets provided there, these light sources seemed closest to daylight in their classes, in decreasing order of daylight approximation:
Compare them and decide which light source you’d choose to supply to a human vision system that evolved under daylight.
The Solux’s (tungsten halogen) SPD looks great, but Solux lamps are only available as 120 VAC PAR and 12 VAC MR16.
The LSI’s (LED + cold phosphor) SPD looks good, but it’s a big museum light fixture.
The Leelium’s (tungsten halogen) SPD looks OK, but it’s a big ballooon used for movie lighting.
The Philips’s (tungsten halogen) SPD looks OK. Tungsten halogen lamps are widely available in a bunch of common form factors.
The CRS’s (LED) SPD looks mediocre. It’s a 12 VAC MR16.
The GE’s (fluorescent) SPD looks bad.
The Pro-Lite’s (compact fluorescent) SPD looks terrible.
In short: tungsten halogen > tungsten > LED > fluorescent.
I wouldn’t be in a hurry to eradicate tungsten lamps. LED and fluorescent lamps have a ways to go before approaching the SPD of tungsten lamps.
My wife and I are engineers. We have young children, and we're concerned about the effect the light sources we use in the house have on their developing visual systems. The human visual system evolved under daylight. It seems reasonable to prefer light sources that more closely approximate the SPD of daylight. So we use tungsten halogen lamps throughout the house. We won’t change over to LED or compact fluorescent lamps until they offer SPDs substantially closer to daylight’s.
Reducing power consumption is a worthwhile goal. But before telling people what light sources they can and cannot use, we should consider the effect those light sources have on human visual development. (“Think of the children!”) I’m surprised I haven’t heard anyone mention the spectral power distributions (SPDs) of light sources in this debate.
You can compare SPDs of some different light sources at, for example, SPD Curves. Select “Update graph” to choose the data series to chart. You can overlay multiple SPD curves for comparison. The curves are all normalized sensibly.
Among the data sets provided there, these light sources seemed closest to daylight in their classes, in arguably decreasing order of daylight approximation:
Compare them and decide which light source you’d choose to supply to a human vision system that evolved under daylight.
The Solux’s (tungsten halogen) SPD looks great, but Solux lamps are only available as 120 VAC PAR and 12 VDC MR16. The LSI’s (LED + cold phosphor) SPD looks good, but it’s a big museum light fixture. The Philips’s (tungsten halogen) SPD looks OK, and tungsten halogen lamps are widely available in a bunch of common form factors. The Cooper’s (LED) SPD looks mediocre, and it’s another exotic lamp form factor. The GE’s (fluorescent) SPD looks bad, and the Pro-Lite’s (compact fluorescent) SPD looks terrible.
In short: tungsten halogen > tungsten > LED > fluorescent.
I wouldn’t be in a hurry to eradicate tungsten lamps. LED and fluorescent lamps have a ways to go before approaching the SPD of tungsten lamps.
We have young children, and I’m concerned about the effect the light sources we use in the house have on their developing visual systems. The human visual system evolved under daylight. It seems reasonable to prefer light sources that more closely approximate the SPD of daylight. So we use tungsten halogen lamps throughout the house. We won’t change over to LED or compact fluorescent lamps until they offer SPDs substantially closer to daylight’s.
Slashdot Mirror
You can compare SPDs of different light sources at The National Gallery's SPD Curves web site. Select “Update selection” to choose the data series to chart. You can overlay multiple SPD curves for comparison. The curves are all normalized sensibly.
Among the data sets provided there, these light sources seemed closest to daylight in their classes, in decreasing order of daylight approximation:
1. Nature Studio2 Filtered Daylight [daylight baseline]
2. Solux 12V Dichroic [tungsten halogen MR16]
3. LSI LumeLEX 2040-C4M2-6S [LED + cold phosphor fixture]
4. Leelium Daylight MSR [tungsten halogen balloon]
5. Philips 50Par30L-WFL40 [tungsten halogen PAR30]
6. CRS SP12 WW [LED MR16]
7. GE F40W/AD [fluorescent T12]
8. Pro-Lite Daylight SRI-30W [compact fluorescent PAR30]
Compare them and decide which light source you’d choose to supply to a human vision system that evolved under daylight.
The Solux’s (tungsten halogen) SPD looks great, but Solux lamps are only available as 120 VAC PAR and 12 VAC MR16.
The LSI’s (LED + cold phosphor) SPD looks good, but it’s a big museum light fixture.
The Leelium’s (tungsten halogen) SPD looks OK, but it’s a big ballooon used for movie lighting.
The Philips’s (tungsten halogen) SPD looks OK. Tungsten halogen lamps are widely available in a bunch of common form factors.
The CRS’s (LED) SPD looks mediocre. It’s a 12 VAC MR16.
The GE’s (fluorescent) SPD looks bad.
The Pro-Lite’s (compact fluorescent) SPD looks terrible.
In short: tungsten halogen > tungsten > LED > fluorescent.
I wouldn’t be in a hurry to eradicate tungsten lamps. LED and fluorescent lamps have a ways to go before approaching the SPD of tungsten lamps.
My wife and I are engineers. We have young children, and we're concerned about the effect the light sources we use in the house have on their developing visual systems. The human visual system evolved under daylight. It seems reasonable to prefer light sources that more closely approximate the SPD of daylight. So we use tungsten halogen lamps throughout the house. We won’t change over to LED or compact fluorescent lamps until they offer SPDs substantially closer to daylight’s.
Reducing power consumption is a worthwhile goal. But before telling people what light sources they can and cannot use, we should consider the effect those light sources have on human visual development. (“Think of the children!”) I’m surprised I haven’t heard anyone mention the spectral power distributions (SPDs) of light sources in this debate.
You can compare SPDs of some different light sources at, for example, SPD Curves. Select “Update graph” to choose the data series to chart. You can overlay multiple SPD curves for comparison. The curves are all normalized sensibly.
Among the data sets provided there, these light sources seemed closest to daylight in their classes, in arguably decreasing order of daylight approximation:
Nature Studio2 Filtered Daylight [daylight baseline]
Solux 12V Diachroic [tungsten halogen 12 VDC MR16]
LSI LumeLEX 2040-C4M2-6S [LED + cold phosphor fixture]
Philips 50Par30L-WFL40 [tungsten halogen PAR30]
Cooper DL11-WS-WW [multi-die LED fixture]
GE F40W/AD [fluorescent T12]
Pro-Lite Daylight SRI-30W Par 30 [compact fluorescent PAR30]
Compare them and decide which light source you’d choose to supply to a human vision system that evolved under daylight.
The Solux’s (tungsten halogen) SPD looks great, but Solux lamps are only available as 120 VAC PAR and 12 VDC MR16. The LSI’s (LED + cold phosphor) SPD looks good, but it’s a big museum light fixture. The Philips’s (tungsten halogen) SPD looks OK, and tungsten halogen lamps are widely available in a bunch of common form factors. The Cooper’s (LED) SPD looks mediocre, and it’s another exotic lamp form factor. The GE’s (fluorescent) SPD looks bad, and the Pro-Lite’s (compact fluorescent) SPD looks terrible.
In short: tungsten halogen > tungsten > LED > fluorescent.
I wouldn’t be in a hurry to eradicate tungsten lamps. LED and fluorescent lamps have a ways to go before approaching the SPD of tungsten lamps.
We have young children, and I’m concerned about the effect the light sources we use in the house have on their developing visual systems. The human visual system evolved under daylight. It seems reasonable to prefer light sources that more closely approximate the SPD of daylight. So we use tungsten halogen lamps throughout the house. We won’t change over to LED or compact fluorescent lamps until they offer SPDs substantially closer to daylight’s.