4 ms·

Higher kelvin lights look so much better in my opinion. http://i.imgur.com/XHqUPOY.jpg http://i.imgur.com/XHqUPOY.jpg

wlesieutre 11y ago
That also has a lot to do with the whole emission spectrum, not just where it falls on the black body curve. Low pressure sodium, for example, is a very narrow wavelength spike [1]. If you look at your hands under this, they appear as a kind of nasty gray with veins sticking out. Awful color rendering. [2] On the flip side, it doesn't scatter as strongly in the atmosphere, and the narrow wavelength band is much easier to filter out of measurements. So there's a tradeoff. If you don't care about dark skies, then phosphor-converted blue LEDs look like a pretty great idea. If you do, then make an informed decision based on the pros and cons of each side. I'm in the lighting industry, and man has there been a lot of sillyness with LED uptake. Great for driving demand and pushing LED research and manufacturing forward, but you get tired of explaining that no, maybe fluorescent or metal halide would be a better tool for some jobs. We're getting to a point where it'd be very infrequent for me to suggest them now, but the last couple of years... [1] https://en.wikipedia.org/wiki/Sodium-vapor_lamp#/media/File:SOX.png https://en.wikipedia.org/wiki/Sodium-vapor_lamp#/media/File:... [2] http://www.lighting-gallery.net/gallery/albums/userpics/11340/normal_LPS-ColorRendering.png http://www.lighting-gallery.net/gallery/albums/userpics/1134...
- probinso 11y ago
  !Agree I'm very excited to have stumbled on this article on HN, as I am presently working on a project in this space; focusing on better ways to specify lighting needs and discuss light pollution's impact on terrestrial telescopes and astronomy. Its neat to see that understanding consequences of artificial lighting, especially wrt. blue light content, is gaining awareness in the market. I've been consulting with a company, that designs lighting whose spectral profile match specifications representative of ecological, industry, and human needs of a region.
  - wlesieutre 10y ago
    The other advantage that LEDs have is that it's really easy to do efficient fixtures with full-cutoff (no direct uplight), since LEDs are a directional light source. You can get that with HID sources too, but it means wrapping the whole thing in a reflector and having a flat lens on that bottom that doesn't drop below the housing: http://www.galleryoflights.org/mb/gallery/albums/userpics/IMG_4931~0.JPG http://www.galleryoflights.org/mb/gallery/albums/userpics/IM... It's really the decorative pedestrian-scale street lights where cutoff is a problem. People like their friendly/traditional looking lanterns and glowing spheres.
bluthru 11y ago
If the existing was the left side and the new was the right, would you feel the same way? I would definitely feel a lot safer on the left side, which is one of the main goals of night lighting.
- vacri 11y ago
  Your eyes adapt, though. Compare the shadow patches on the right side versus the shadow patches on the left. The left side is much clearer in the light patches, but the right is more consistent overall (supporting what cauterized says above about shadows). Another sleeper issue with rapidly changing light and dark patches is that if you manage to get them to flicker around 10-14Hz (driving through light+dark patches), you're going to provoke the occasional photoresponsive epileptic seizure. This has been seen in some roads in France where the trees were spaced in such a way that when the sun is low in the sky, it creates such a flicker. I don't know what the rate would be for driving along that road at a normal rate, but I'd be curious to find out. If it's a relatively short road, it would be unlikely to flicker long enough to provoke a seizure, even in the right frequency ranges.
  - bluthru 11y ago
    >Your eyes adapt, though. Not to the point where one would feel as safe on the right as they do to the left. >the right is more consistent overall That's because of the fixtures--there's a reason they are causing lens flares while the left side isn't.
    - simoncion 11y ago
      If "feels safe" is our goal, we're gonna be chasing those taillights forever. :/ I live on an incredibly well lit block in a very well lit part of SF. [0] I'm a couple of blocks away from a substantially less well lit block. [1] It's much more enjoyable to walk through the less well lit block than the more well lit ones. I expect that it's significantly nicer for the folks living in the apartments on that block, too. Light pollution also affects people who aren't astronomers. :( [0] Seriously, you can easily read a book on the street in just about any part of the TL. On my block, the fixtures are 50->75% as bright as daylight. [1] That is to say, you'd have to strain your eyes to read a book on that section of the street.

That also has a lot to do with the whole emission spectrum, not just where it falls on the black body curve. Low pressure sodium, for example, is a very narrow wavelength spike [1]. If you look at your hands under this, they appear as a kind of nasty gray with veins sticking out. Awful color rendering. [2] On the flip side, it doesn't scatter as strongly in the atmosphere, and the narrow wavelength band is much easier to filter out of measurements. So there's a tradeoff. If you don't care about dark skies, then phosphor-converted blue LEDs look like a pretty great idea. If you do, then make an informed decision based on the pros and cons of each side. I'm in the lighting industry, and man has there been a lot of sillyness with LED uptake. Great for driving demand and pushing LED research and manufacturing forward, but you get tired of explaining that no, maybe fluorescent or metal halide would be a better tool for some jobs. We're getting to a point where it'd be very infrequent for me to suggest them now, but the last couple of years... [1] https://en.wikipedia.org/wiki/Sodium-vapor_lamp#/media/File:SOX.png https://en.wikipedia.org/wiki/Sodium-vapor_lamp#/media/File:... [2] http://www.lighting-gallery.net/gallery/albums/userpics/11340/normal_LPS-ColorRendering.png http://www.lighting-gallery.net/gallery/albums/userpics/1134...

probinso 11y ago
!Agree I'm very excited to have stumbled on this article on HN, as I am presently working on a project in this space; focusing on better ways to specify lighting needs and discuss light pollution's impact on terrestrial telescopes and astronomy. Its neat to see that understanding consequences of artificial lighting, especially wrt. blue light content, is gaining awareness in the market. I've been consulting with a company, that designs lighting whose spectral profile match specifications representative of ecological, industry, and human needs of a region.
- wlesieutre 10y ago
  The other advantage that LEDs have is that it's really easy to do efficient fixtures with full-cutoff (no direct uplight), since LEDs are a directional light source. You can get that with HID sources too, but it means wrapping the whole thing in a reflector and having a flat lens on that bottom that doesn't drop below the housing: http://www.galleryoflights.org/mb/gallery/albums/userpics/IMG_4931~0.JPG http://www.galleryoflights.org/mb/gallery/albums/userpics/IM... It's really the decorative pedestrian-scale street lights where cutoff is a problem. People like their friendly/traditional looking lanterns and glowing spheres.

bluthru 11y ago

If the existing was the left side and the new was the right, would you feel the same way? I would definitely feel a lot safer on the left side, which is one of the main goals of night lighting.

vacri 11y ago
Your eyes adapt, though. Compare the shadow patches on the right side versus the shadow patches on the left. The left side is much clearer in the light patches, but the right is more consistent overall (supporting what cauterized says above about shadows). Another sleeper issue with rapidly changing light and dark patches is that if you manage to get them to flicker around 10-14Hz (driving through light+dark patches), you're going to provoke the occasional photoresponsive epileptic seizure. This has been seen in some roads in France where the trees were spaced in such a way that when the sun is low in the sky, it creates such a flicker. I don't know what the rate would be for driving along that road at a normal rate, but I'd be curious to find out. If it's a relatively short road, it would be unlikely to flicker long enough to provoke a seizure, even in the right frequency ranges.
- bluthru 11y ago
  >Your eyes adapt, though. Not to the point where one would feel as safe on the right as they do to the left. >the right is more consistent overall That's because of the fixtures--there's a reason they are causing lens flares while the left side isn't.
  - simoncion 11y ago
    If "feels safe" is our goal, we're gonna be chasing those taillights forever. :/ I live on an incredibly well lit block in a very well lit part of SF. [0] I'm a couple of blocks away from a substantially less well lit block. [1] It's much more enjoyable to walk through the less well lit block than the more well lit ones. I expect that it's significantly nicer for the folks living in the apartments on that block, too. Light pollution also affects people who aren't astronomers. :( [0] Seriously, you can easily read a book on the street in just about any part of the TL. On my block, the fixtures are 50->75% as bright as daylight. [1] That is to say, you'd have to strain your eyes to read a book on that section of the street.