Comment by userbinator
1 day ago
Very interesting. I've always thought that there was something a bit "off" about LED torches and car headlamps; the brightness is there, but something about the light just doesn't seem to illuminate as well as an old dim incandescent or even fluorescent tube.
It's usually the Color Rendering Index (the spectrum of frequencies that the light puts out). Incandescent bulbs more of less mimic that of the Sun, they are "black body radiators". Cheap LEDs tend to be missing a lot of the red spectrum.
However, you can get LEDs that do this well. Look for one with a "CRI" of 95% or higher.
The CRI is an imperfect metric, I watch for both CRI and R9, both should be high.
There's a massive difference between the 2600K of regular incandescent bulbs, and the 6000K of sunlight. That's why hollywood used HMIs until they migrated to LED.
There is, but most humans are used to the spectral pattern of black body radiators at all color temperatures. Be that sunlight at higher temperatues or fires / candlelight at lower temperatures.
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For professional applications there are sulfur plasma lamps which have a continuous spectrum at high efficiency. Unfortunately they aren't economical below about 1000 watts which is impractical for many applications.
The technology basically works by continuously microwaving (think oven) a small amount of sulfur gas. The development of solid-state microwave emitters — most microwave generation is still done with vacuum tubes — might help miniaturize the devices. However, it's hard to beat the simplicity of an LED.
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Yes lots of them use cheap LEDs with poor CRI, high color temperature, and a huge blue spike in the spectrum. All of that leads to a very bright looking light that also doesn't let you see detail very well.
They're saying that the visual performance is indirectly affected by invisible wavelengths somehow. Not that you can see the difference between two types.
They are saying that, and most real world LED lighting uses very cheap diodes, like, 99.9999% of them, which create very poor colour compared with incandescent bulbs, which create perfect colour representation.
It's a big thing and you can buy LEDs which produce a better colour range, but they're much more expensive and not as energy efficient, because creating bold reds costs hard energy that no diode trick will ever get around that.
>They are saying that, and most real world LED lighting uses very cheap diodes, like, 99.9999% of them, which create very poor colour compared with incandescent bulbs, which create perfect colour representation.
Have you actually read the study? It's about infrared and has nothing to do with color rendering and visible spectrum. They're vaguely speculating about some mitochondrial mechanism of action not related to vision at all.
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I get that they're more efficient in some sense, but man the LED streetlights and other big lamps are so irritating and make things like like such ass compared to mercury vapor or even sodium lights.
True. Yet, somehow more and more cities install them blindly because efficiency. I remember when I moved to Odense Denmark in 2013 - they had LED street lights all over the place. I thought - this is the future compared to my uderdeveloped post soviet Latvia. And yet, I remeber when I moved back, streets at night looked so yellow because the city still relied on sodium lights. And my eyes felt much more comfortable. At the time I wrote it off to nostalgia or something, and here we are.
Even a colour filter would help with the harshness.
True, but that lowers the energy efficiency.
For LED lamps, the color must be controlled at the emission source, not by filtering, i.e. by using an adequate combination of different conversion phosphors, to ensure a neutral white with a quasi-continuous spectrum, instead of a bluish white with great narrow peaks in its spectrum.
Unfortunately, the phosphors for the latter variant are much cheaper than for the former, so the lamp vendors have the incentive to make the lamps as bad as possible.
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