3 ms·

The effect would have to be stronger than the differences in luminous efficacy to work, which is about 10% between 3000K and 4000K. This is a great theory, but

The effect would have to be stronger than the differences in luminous efficacy to work, which is about 10% between 3000K and 4000K. This is a great theory, but you provide no supporting evidence. The "bogus" metrics you complain about are based around real color research done in 1931, far before people were marketing LEDs: https://en.wikipedia.org/wiki/Luminous_flux https://en.wikipedia.org/wiki/Luminous_flux

jacobolus 9y ago
No, I’m talking about stuff like https://scholar.google.com/scholar?q=mesopic+efficiency https://scholar.google.com/scholar?q=mesopic+efficiency (add keywords about street lamps and car headlamps if you want more recent and specific results). The relevant literature is mostly from the past few decades, and ongoing. Luminous efficiency is not the only thing we should care about here. What we want is for the road and objects on it to be clearly visible to someone with dark-adapted vision, and for individual sources of light to be visible but not cause glare or distraction. Obviously a brighter light does a better job of making itself visible and illuminating things directly in its path; the problem is that brighter lights which are intense in the blue part of the spectrum cause more glare and more adaptation than dimmer yellower lights, which makes everything that isn’t being directly lit by them effectively less visible. If objects directly under the sweep of car headlamps are lit to the same extent as during a sunny day, then the shadowy bushes off to the side of the road and the kid running out from behind them are going to be very dark by comparison. I’m not an expert in this specific topic (I’ve studied much more about color vision under well lit conditions), but several of the papers I skimmed when I started looking into it because I was frustrated about my street’s new LED lamps seemed to be funded by industry, and I’m not convinced that their experiments mirror real-world conditions of nighttime streets, or properly measure the effects of adaptation and glare. The lighting industry wants to use a measure of luminous power based on “mesopic conditions” (i.e. mix of photopic + scotopic) because if they use the photopic function then blue light doesn’t really contribute much and their lamps don’t look as efficient or bright. My personal experience is that bright sources of blue light in my peripheral vision cause enough adaptation that I’m not convinced that a “mesopic” function as they’re using it is actually appropriate. I should probably email some real color scientists to ask for clarification someday. If you know of a nice survey paper written by someone with industry-independent bona fides, I’d love to skim it.

jacobolus 9y ago

No, I’m talking about stuff like https://scholar.google.com/scholar?q=mesopic+efficiency https://scholar.google.com/scholar?q=mesopic+efficiency (add keywords about street lamps and car headlamps if you want more recent and specific results). The relevant literature is mostly from the past few decades, and ongoing. Luminous efficiency is not the only thing we should care about here. What we want is for the road and objects on it to be clearly visible to someone with dark-adapted vision, and for individual sources of light to be visible but not cause glare or distraction. Obviously a brighter light does a better job of making itself visible and illuminating things directly in its path; the problem is that brighter lights which are intense in the blue part of the spectrum cause more glare and more adaptation than dimmer yellower lights, which makes everything that isn’t being directly lit by them effectively less visible. If objects directly under the sweep of car headlamps are lit to the same extent as during a sunny day, then the shadowy bushes off to the side of the road and the kid running out from behind them are going to be very dark by comparison. I’m not an expert in this specific topic (I’ve studied much more about color vision under well lit conditions), but several of the papers I skimmed when I started looking into it because I was frustrated about my street’s new LED lamps seemed to be funded by industry, and I’m not convinced that their experiments mirror real-world conditions of nighttime streets, or properly measure the effects of adaptation and glare. The lighting industry wants to use a measure of luminous power based on “mesopic conditions” (i.e. mix of photopic + scotopic) because if they use the photopic function then blue light doesn’t really contribute much and their lamps don’t look as efficient or bright. My personal experience is that bright sources of blue light in my peripheral vision cause enough adaptation that I’m not convinced that a “mesopic” function as they’re using it is actually appropriate. I should probably email some real color scientists to ask for clarification someday. If you know of a nice survey paper written by someone with industry-independent bona fides, I’d love to skim it.