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The Light that will Be
February 3, 2014 9:52 AM   Subscribe

After Michael Mann set out to direct Collateral, the story’s setting moved from New York to Los Angeles. This decision was in part motivated by the unique visual presence of the city — especially the way it looked at night. Mann shot a majority of the film in HD (this was 2004), feeling the format better captured the city’s night lighting. Even the film’s protagonist taxi needed a custom coat to pick up different sheens depending on the type of artificial lighting the cab passed beneath. That city, at least as it appears in Collateral and countless other films, will never be the same again. L.A. has made a vast change-over to LED street lights, with New York City not far behind. Why Hollywood Will Never Look the Same Again on Film: LEDs Hit the Streets of LA & NY
posted by timshel (71 comments total) 23 users marked this as a favorite

 
Our street just got LED lights; not sure they are an improvement. The brighter, bluer light makes the shadows that much darker and more confusing.
posted by migurski at 9:54 AM on February 3 [1 favorite]


Are there any studies of human preference for different lighting types? We got an LED bulb for indoors. Hate it so much it now lights the outside.
posted by IndigoJones at 10:00 AM on February 3 [1 favorite]


Ummm. Orange is something new. It's called sodium vapor, or HPS, High Pressure Sodium. When I was a kid, it was all blue-green or purple mercury lights - and when I was real little kid, the streetlamp on the telephone pole at the corner was incandescent, with a frilly little reflector/shield thing on top.

One of my most vivid memories of the Boston area when I moved there in the Mid '90s was of a snowstorm I had drive through, down the 128 corridor, the entire sky lit up purple and orange depending on whether they had mercury or sodium lights or both.

More, good riddance. HPS lights in recent years have become sources of tremendous light pollution - LED lights put the light on the pavement, and is much softer, due to multiple emitters, so the shadows aren't as stark. They have them in the lot at my office, and they're a dramatic improvement.
posted by Slap*Happy at 10:03 AM on February 3 [13 favorites]


If they ever do this in Chicago my heart will break.
posted by phunniemee at 10:12 AM on February 3 [5 favorites]


FWIW I love the 12 V warm temperature LED bulbs I put in my vehicle -- can't tell the difference. I still haven't found a good replacement for the standard household bulb.

(Also, I find it hard to get upset about movies being different forever when 100% of them are digitally composited or corrected in some way)
posted by RobotVoodooPower at 10:15 AM on February 3 [2 favorites]


Wow, that photo of Chicago looks like a scene from a scifi movie: " as the shuttle approached the polluted surface of the alien planet ..."
posted by Kirth Gerson at 10:18 AM on February 3 [4 favorites]


I was all going to rant, but Slap*Happy beat me to in on pretty much every point…

If they ever do this in Chicago my heart will break.

I would avoid Western Ave. and Lake Shore Drive at night, then. (Though I'm not sure what technology they're testing there -- but the light looks vastly better.)

And screw it. Uncutoff LP sodium lights are an outright bane. I want white light, and I want it on the ground, not in the sky, not in my eyes.

The one group this does truly screw -- astronomers. LP sodium is trivial to filter out, but broadband isn't. I suspect that lighting near established observatories, along with the other restrictions, will remain LP sodium for that reason alone.

Are there any studies of human preference for different lighting types?

Yes, and LEDS can emulate most of them. But if you want a warm light LED, which is aiming for a 3200°K incandescent white point, and you buy a 5700°K daylight lamp, you're going to be very unhappy at the very blue light that it emits compared to 3200°K tungsten or 3400° tungsten-halogen incandescent lamps.

Tungsten-Halogen lamps are a tiny bit bluer (Higher temps= more blue) in light because the filament is glowing at a slightly higher temperature, but it's hard to tell, even burning right next to a normal incandescent lamp -- basically, they just appear a little more…moreish to my eyes. I like them, and use them where I can't stand CFLs. If LEDs get close to that light, I'll happily buy them.
posted by eriko at 10:22 AM on February 3 [6 favorites]


I'll admit I was a little wary when the city hired Olafur Eliasson to replace the streetlights with an enormous and baleful orange orb, but it was an improvement on when we had the bioluminescent lichen mixed into the asphalt and you couldn't see a goddamn thing.
posted by theodolite at 10:33 AM on February 3 [11 favorites]


It was pretty jarring to Dallas' skyline when Reunion Tower was switched over to LED a few years back. Instead of the occasional soccer ball pattern, we now get tacky crap like this.
posted by item at 10:37 AM on February 3


But if you want a warm light LED, which is aiming for a 3200°K incandescent white point, and you buy a 5700°K daylight lamp, you're going to be very unhappy at the very blue light that it emits compared to 3200°K tungsten or 3400° tungsten-halogen incandescent lamps.

I was surprised when I started looking at LED bulbs that the bulbs that best match daylight seemed very "artificial" in my house. I hadn't realized how yellow incandescent bulbs are, and how much I was used to their color. Just looking at paint color, however, I realized quickly that the light from the ~6000 K lamps did a pretty good job of emulating sunlight.

Still, I feel comfortable with yellower light, and have found some LED lamps that reproduce tungsten incandescents well...
posted by mr_roboto at 10:40 AM on February 3


Uh oh. I'm at the extreme end of "sensitive to light quality" and I don't know if New York's changing to LED is going to be for the better or worse, but it's easy enough to predict "worse."
posted by Navelgazer at 10:49 AM on February 3


Movies shot on digital, LED street lights, less and less resources devoted to lighting technicians and their training in favor of digital manipulation.. it's destroying that look Mann talks about. The same way that you watch The Robe and wonder at the majesty of the scope and color compared to modern movie epics.

When I was a teenager, a friend of mine was telling me after we had gone and seen the special edition of A New Hope at a local theater how in the not too distant future movies would be delivered digitally. Ever the romantic, I balked. Claiming that people would never stand for the dry, cold nature of digital. Time proved me wrong on his part, but I still feel like time will prove me right on mine as well.
posted by mediocre at 10:54 AM on February 3 [3 favorites]


LEDs must be better than the yellow sodium lights. Those things are somehow simultaneously glaring and unilluminating.
posted by sonic meat machine at 10:54 AM on February 3 [1 favorite]


I expect filmmakers will actually like the LEDs better. Sodium lights give a certain look, yes, but it's pretty much the only look they give. The spectrum is so narrow that you're not capturing any color information at all, which makes grading that much more difficult. Everything's digitally graded to whatever look the director or DOP had in mind anyway, and the LED lights will give them more information to use. If someone wants to make their night scenes lit by the glowing eye of Sauron like they all used to be, they can still do that.
posted by echo target at 10:55 AM on February 3 [3 favorites]


How I long for the days when the streets were lit with the screaming heads of the Dark Master's enemies. You kids don't know what you are missing! I admit the screaming got a little tiresome, but it helped with accessibility efforts for the visually impaired.
posted by GenjiandProust at 10:57 AM on February 3 [8 favorites]


Prediction: Any change whatsoever will be reviled, criticized, and labeled "the worst possible change".

One to one-half generation later, it will be clung to as the traditional and best lighting.
posted by IAmBroom at 10:58 AM on February 3 [22 favorites]


I, for One, have beene tarnal Wrothy hever synnce They bann'd the Train Oil fer th' sayke of Greate Mysticeti.
posted by Ice Cream Socialist at 10:59 AM on February 3


Came for the LEDs, stayed for the techie comments section..
posted by bird internet at 11:00 AM on February 3 [1 favorite]


yeah the orange sky in Chicago, especially when its snowing so the cloud cover and the snow cover are intensifying the reflectivity, is really something else. intense and slightly sickly at the same time..

never any stars, though..
posted by ninjew at 11:02 AM on February 3


ugh the sickly pallor of sodium-vapour light reflecting off the ground-level atmospheric ceiling is the worst part of moving to Chicago. I wear a sleep mask every night now so I don't wake up at 4am thinking I'm in Blade Runner.

and I love Blade Runner
posted by a halcyon day at 11:10 AM on February 3 [4 favorites]


Metafilter: somehow simultaneously glaring and unilluminating.
posted by Mapes at 11:11 AM on February 3 [8 favorites]


Chris Hadfield's overhead shot of Berlin at night is a lovely view of the difference in streetlight color temperature, in this case following the old East/West division.
posted by Nelson at 11:11 AM on February 3 [3 favorites]


The brighter, bluer light makes the shadows that much darker and more confusing.

I think the starkness is partly related to the fact that LEDs tend to be very intense pinpoints of light rather than more gently illuminated globes. Our streetlights were replaced a while ago, and I thought this was the most noticeable difference -- the light that was once produced by perhaps 60 square inches of surface area was now concentrated into half a dozen tiny spots. Each spot is so intense that it hurts to look at directly, especially if your eyes have somewhat adjusted to the dark.

The thing is, this seems like it would be so easy to fix -- residential lights all (or mostly) surround the lighting elements with a translucent globe to scatter the light. But I guess that was considered a frivolous expense for streetlights.

On film, I would have thought the flicker would be a concern as well. Maybe it's more pronounced with the kind of short-interval digital shutter you get on consumer cameras, but I've definitely noticed this in my own video clips -- the pulsed output of LED lights is instantly apparent.
posted by bjrubble at 11:13 AM on February 3


Yeah, I was just about to mention the Berlin thing. I think I saw somewhere else that they were actually trying to preserve the dichotomy with differently tuned LEDs when they switch.
posted by ckape at 11:13 AM on February 3


Most of the streetlights in my residential neighborhood of Austin have been converted to LED. I love them. Each head has something like 9 individual LED elements in a tic-tac-toe matrix, and when they shine through the leaves of trees, they make amazing interference patterns on the ground.
posted by adamrice at 11:15 AM on February 3 [2 favorites]


I still miss the green lights that used to illuminate Lower Wacker Drive here in Chicago:
That eerie, green gleam on Lower Wacker was a city landmark, as familiar to generations of Chicagoans as the Water Tower or the Marshall Field's clock. ... And for more than 40 years, the chunk of lower Wacker--from Lake Street south--has had that bright green Oz-zy haze, thanks to rows of green-tinted, six-foot-long fluorescent light bulbs.
...
In the '50s, when the green lights went in, it was thought that their wacky color would cast more light than the normal fluorescent bulb, making it easier for motorists to negotiate the diabolical obstacle course of barriers, pillars, islands and other hazards on Lower Wacker.

Chicago Tribune, "Efficiency Casts Its Shadow Over Emerald Highway", February 23, 1996
posted by orthicon halo at 11:18 AM on February 3 [1 favorite]


It's happening in London, too.
posted by timshel at 11:19 AM on February 3


How I long for the days when the streets were lit with the screaming heads of the Dark Master's enemies.

That's technically not lighting -- the screaming heads are actually taking in the darkness and emitting it sonically. There seems to be more brightness, but really it's just less darkness.
posted by ROU_Xenophobe at 11:24 AM on February 3 [7 favorites]


I live next to a major street that was switched from sodium to white LEDs a couple years ago. How anybody would consider sodium lighting better is beyond me -- but I've read ancient testimonials about people actually preferring the 'golden' sodium lighting, when it replaced the dimmer mercury vapor and incandescents.
posted by Rash at 11:24 AM on February 3


We should just go back to arc lamp moontowers.
posted by ckape at 11:25 AM on February 3 [6 favorites]


Lighting tech here...I imagine that nothing much will change in my world...there will still be days of gelling windows and lamps and changing bulbs, just like always. If you can't make it the correct temp with technology, there's always the old way.
posted by nevercalm at 11:25 AM on February 3 [3 favorites]


So...this isn't the thread where we talk about how great Collateral is?

I mean, the ending's kind of goofy, but it's still a lot of fun, beautifully shot, and Tom Cruise does actual acting in it.
posted by Rangeboy at 11:31 AM on February 3 [8 favorites]


Tom Cruise does actual acting in it.

Sadly, Tom Cruise the media identity gets a lot more asses in seats then Tom Cruise the actor. But damn if he doesn't impress me in nearly every role he does, no matter how much Scientology blather he can froth. I am greatly anticipating Edge Of Tomorrow, despite the stupid name change.
posted by mediocre at 11:36 AM on February 3 [1 favorite]


So...this isn't the thread where we talk about how great Collateral is?

It can be. Apropos of almost nothing, this is one of my favourite examples of urban light being used in an expressionistic way for a movie. Yes it's all fake and so what.
posted by timshel at 11:39 AM on February 3 [1 favorite]


RangeBoy: CalArts film professor Thom Andersen, he of "Los Angeles Plays Itself" isn't as fond of the film as you are, but he has some nice things to say about it, in this 2006 essay. He especially seemed to love the photography, while specifically addressing his shots of downtown.

I read another interview with him, years ago, in which he suggested that he loved the red-roofed taxis, found them an improvement upon those of real life, and also favored keeping the subways open longer, as they were in the film.
posted by raysmj at 11:56 AM on February 3 [2 favorites]


michael mann loves his scenes shot at night

there's so many more, i was just having trouble finding good images
posted by ninjew at 12:12 PM on February 3


I love Collateral, and play a lot of stuff from the soundtrack a lot. The scene with the coyote is one of those moody moments I love.
posted by PussKillian at 12:22 PM on February 3 [1 favorite]


We should just go back to arc lamp moontowers.

This seems like a great idea until the Great Enemy casts down the tower and creates an inland sea.
posted by The Tensor at 12:36 PM on February 3 [2 favorites]


Thanks for the link, raysmj. This also seems as good an opportunity as any to point out that the Criterion Blu-ray of Thief just came out.
posted by Rangeboy at 1:02 PM on February 3


That's technically not lighting -- the screaming heads are actually taking in the darkness and emitting it sonically. There seems to be more brightness, but really it's just less darkness.

Have your eyes not been modified to behold the Dark Master's unspeakable visage? The screaming heads give off a most illuminating light. I think you had best make an appointment at the veneratory before the Pain Dogs come calling....

And the Pain Dogs, I understand, are worse than the Chicago night sky.
posted by GenjiandProust at 1:17 PM on February 3


Surprised no one had mentioned the massive energy and maintenance savings of using led. Not very romantic I guess but saves your city money and the environment at the same time.
posted by smoke at 1:55 PM on February 3 [2 favorites]


I'm pretty conservative when it comes to change, but our new LED streetlights are really nice. The front street used to have an orange DANGER glow to it, but now it's all silvery like moonlight.
posted by Kevin Street at 2:26 PM on February 3


LEDs are getting better and better. I've seen some that are darn near perfect-looking for incandescent swapouts.

HOWEVER, the only way to regulate the brightness of an LED is to switch it off. Yep. If you've ever wondered why tail lights on cars look weird when you move your head or turn your eyes is because you're seeing it flicker. And the dimmer it goes, the longer it is "off" during the flickering process. The flickering of a dimmed LED is *supposed* to be faster than the rate at which your eyes can detect it -- but only if your eye is stationary. Turn your eye or your head, and you'll see the flicker.

And I really, really hate that flicker. Hopefully in a few years even that problem might be solved...

At least LEDs are a huge improvement over the nuclear death lamps - er, fluorescents.
posted by chimaera at 2:47 PM on February 3


speaking of changes in public lighting technology, does anyone know what color temperature gas lighting was? i've always been curious about what streets and interiors looked like under gas lamps.
posted by titus n. owl at 3:06 PM on February 3


Surprised no one had mentioned the massive energy and maintenance savings of using led.

It's mentioned prominently in TFA.
posted by Kirth Gerson at 3:17 PM on February 3 [1 favorite]


I read the Collateral script in the early 2000s, when it was set in New York, and it felt like a love-letter to New York at night—a city I think is at its best after dark. The story and the setting sat together like an integral pair. It was a truly great script.

What Mann did to it, translating it to an entirely different and much more anonymous city, was extraordinary. I would still have preferred to have seen the New York version, but his vision transcended the original scriptwriter's (the plot was largely unchanged between the two versions) and it felt completely native. A great movie.
posted by Hogshead at 3:31 PM on February 3 [3 favorites]


HOWEVER, the only way to regulate the brightness of an LED is to switch it off.

It's certainly the most controllable way to dim an LED, but the switching frequency can be arbitrarily fast, certainly well up into the MHz regions.

I find the flicker most annoying when driving on the motorway at night, and the destination board of a coach in the rear-view mirror will appear to wobble around due to the way your eyes can't correct for the multiple different movements and the flickering of the dimmed LEDs (vibration of your head and of the mirror and the microsaccades of your eyes).
posted by ambrosen at 3:56 PM on February 3


The flickering of a dimmed LED is *supposed* to be faster than the rate at which your eyes can detect it -- but only if your eye is stationary. Turn your eye or your head, and you'll see the flicker.

All incandescent lights are flickering on and off in any AC system.
posted by yoink at 4:14 PM on February 3 [1 favorite]


A propos the color temperature thing: I wonder if we'll slowly decondition ourselves to the deeply yellow light of tungsten bulbs? I know a lot of people get freaked out by how "blue" LEDs are because they go for "full spectrum" or "daylight" lighting thinking "sunlight is nice and warm, right?" without every having really noticed that, actually, daylight is incredibly stark and "cold" compared to incandescent light. But, really, there's no reason we should inherently prefer sitting around in yellow-tinged light at night. It seems to me possible that we might eventually opt for having "daylight" quality light for preference and come to see those "warmer" bulbs as weirdly distorting.
posted by yoink at 4:18 PM on February 3


The light of an incandescent bulb is due to the heat of the filament. Cooling a filament to the point it is no longer putting out light takes significantly longer than the an AC mains cycle. So no, it is not flickering.
posted by ckape at 4:33 PM on February 3 [2 favorites]


I'd like the LED lighting next to our house a lot more if it didn't shine straight into the window, bright enough to read by. The TV's in that room. Thicker drapes don't help. I am so tempted to get a slingshot and nothing, officer, not doing anything, just standing here, why do you ask?
posted by Fnarf at 4:46 PM on February 3


Switching the street lights in Chicago is one of my preconditions for moving back. The infernal orange glow on the horizon always made me feel as if I was descending into Mordor. It was like the pollution, of the land, of the air, of the spirit, made manifest as a warning to travelers.
posted by wotsac at 4:49 PM on February 3 [1 favorite]


The light of an incandescent bulb is due to the heat of the filament. Cooling a filament to the point it is no longer putting out light takes significantly longer than the an AC mains cycle. So no, it is not flickering.

They flicker less than a light that shuts off instantaneously, but they still flicker. Have a look at high-speed film of an incandescent light at 60hz some time. Very visible flickering.
posted by yoink at 5:07 PM on February 3


One of the great things about LCD monitors is, I no longer have to go around the office and set people's refresh rate away from 60 Hz to keep their CRTs from strobing with the stupid ubiquitous fluorescent lights and giving everybody migraines. I'm one of the unlucky ones who can see fluorescent tubes flicker, especially if I've just run up a flight of stairs.

Someday LEDs will be everywhere and no one will remember any other. Can't come soon enough for me.
posted by Fnarf at 5:19 PM on February 3


And I really, really hate that flicker. Hopefully in a few years even that problem might be solved...

LEDs illuminate in nanoseconds, so that's how fast you can switch them. Flickering LEDs are the sign of lazy/cheap drivers.

AC driven fluorescents flicker just as badly, you just don't see then moving very often. Incandescents flicker a little bit, in that they very slightly dim every time the AC wave crosses 0, but it takes much longer than 1/50th of a second for them to go dark unless they break, so nobody sees them go dark.

There was an era where we had to pay attention to what light our film was balanced to, and use filters to cope if we had daylight balanced film and tungsten light, or vice versa.
posted by eriko at 5:46 PM on February 3


ckape: "The light of an incandescent bulb is due to the heat of the filament. Cooling a filament to the point it is no longer putting out light takes significantly longer than the an AC mains cycle. So no, it is not flickering."

Not entirely true. In EE lab we built a (low-quality, small-bandwidth) communication link with an incandescent bulb and a photodiode.

The reality is that incandescent filaments are so lightweight that they actually do cool off significantly (via radiation) during the low-voltage portions of the AC cycle. They don't go "dark", but there's a slight flicker - at 120 Hz, because the heating is power-related instead of voltage-related, so there's no chance of noticing it.
posted by IAmBroom at 7:08 PM on February 3 [1 favorite]


LEDs illuminate in nanoseconds, so that's how fast you can switch them. Flickering LEDs are the sign of lazy/cheap drivers.

And it drives me up the wall that in industrial quantities, including development it would add maybe fifty cents to the cost of the car to do it properly even if they had to add an entirely separate driver for it and couldn't just steal an otherwise unused PWM output from something, and yet here we are in 2014 with Dodge LED taillights making me want to go all anti-social with a baseball bat if I have to follow one for more than a mile or so.
posted by Kyol at 8:31 PM on February 3 [1 favorite]


Growing up, I lived in a town that didn't have the sodium lights, so my first encounter with them gave me an instant feeling of revulsion. Years later, the idea that the lights I've grown used to might be going away has given me this bizarre feeling of nostalgia. It's weird. I had to stop myself and have a little internal chat, pointing out that, no, I hate those lights, and I always have, and just because I'm used to them doesn't mean I should feel sad that they're going away.

Chicago was really my first experience with them. I lived about forty-five minutes north of the city, and had the bad fortune to have a south facing bedroom that never, never got completely dark. The dull orange glow (mostly from Palatine and Arlington, honestly) kept my room well lit enough to see the outline of pretty much everything in the room. As someone who has difficulty sleeping, and prefers total darkness, it was pretty hellish.
posted by Ghidorah at 8:57 PM on February 3 [1 favorite]


> the only way to regulate the brightness of an LED is to switch it off. Yep.

Nope.

LEDs look like a short circuit so the current is limited with a resistor (inefficient) or a constant-current switching power supply in buck mode. The ripple of such a supply can be controlled.

Consider figure 1 here [pdf] showing current varying with a dim control variable resistor.

and the first figure here showing luminous flux vs. forward current.
posted by morganw at 11:01 PM on February 3 [2 favorites]


I should mention that while it's possible, almost no one dims high power LEDs by varying the current instead of pulsing them, but some do. Also, fluorescent tubes can be run on DC. Flicker isn't necessary; it's just tolerated by enough people to make it too expensive for those who won't/can't to get flicker-less high efficiency lighting.
posted by morganw at 11:34 PM on February 3


morganw: "I should mention that while it's possible"

What a strange comment. LEDs are diodes; they
have a quasi-linear section to their I/V curve; obviously any LED can be easily regulated in brightness.

Maybe no one does it, but it's very easy to do.
posted by IAmBroom at 12:57 AM on February 4


I know a lot of people get freaked out by how "blue" LEDs are...

Carbide (acetylene) lamps used to be the brightest option for caving, and some people still use them. Acetylene flames are very yellow (about 2300K). The people who still use carbide often complain about the color of LED light, and sometimes even complain that they are "too bright," by which I have always assumed they mean "brighter than what I'm using."

The first time I encountered sodium-vapor street lights was driving through a small town in a heavy snowstorm. It was surreal.
posted by Kirth Gerson at 4:51 AM on February 4


I'm amused at everyone citing Chicago at night, since it was one of the most striking things about moving there when I was thirteen that I remember: even the light is different, I thought to myself. Somewhat disturbing, yes, but also with the thrilling promise that anything could be different.
posted by Halloween Jack at 4:57 AM on February 4 [2 favorites]


> LEDs [...] have a quasi-linear section to their I/V curve; obviously any LED can be easily regulated in brightness.

Color LEDs shift color as current changes. I wondered about this for white LEDs which are really UV LED + fluorescent materials, and it turns out they don't shift much:[PDF] "less than a 4-step MacAdam ellipse"

At the beginning of LEDs used for lighting rather than indication, PWM being a holdover might have made sense, but now we're into lighting-specific drivers at much higher power ratings, it does smell of laziness.
posted by morganw at 7:54 AM on February 4


> daylight is incredibly stark and "cold" compared to incandescent light
However daylight gets warmer at lower lighting levels as it passes through more of the atmosphere. I think that's why dimmed fluorescents and white LEDs look so weird-- only moonlight is dim & cold in nature.
posted by morganw at 7:57 AM on February 4 [1 favorite]


morganw: "Color LEDs shift color as current changes."

Oh, goddammit, of course! An "LED" is actually an array of LEDs (at least, those bright enough to be useful for lighting; those little indicator ones are singles), and white-light LEDs are arrays of various colors with different I/V characteristics.

No wonder everyone dims them with pulse modulation. Duh.

Thanks.
posted by IAmBroom at 9:15 AM on February 4


AC driven fluorescents flicker just as badly, you just don't see then moving very often.

I have to say, it's been a long while since I've seen fluorescents in a work environment with a magnetic ballast. I've seen a few in people's kitchens, though.
posted by ambrosen at 11:27 AM on February 4


> white-light LEDs are arrays of various colors with different I/V characteristics

Not exactly. When I first heard of them, soon after blue LEDs were invented, I thought that too.

Some LEDs emit blue, violet or UV causing white-ish phosphorescence and should not shift, but some emit blue causing yellow scintillation and might. Another wikipedia article mentions even more doping schemes.

The RPI article I linked above actually compares varying current and PWM for both white LEDs and RGB LEDs: "the mixed-color RGB LED system tested in this study showed very large chromaticity shifts in a similar dimming range using both dimming schemes"
posted by morganw at 11:35 AM on February 4


Does anybody know if, in the course of swapping out the lights, there are any cities that are planning to also install deflectors to keep the light directed strictly downward? I'd like to be able to look forward to seeing an impressive night sky without having to drive an hour out of town.
posted by Ipsifendus at 1:58 PM on February 4


You'd still have a lot of light reflected off the streets & everything that the light illuminates.

My favourite replacing-municipal-lights-with-LEDs is from a small town where during the first winter their new LED traffic lights were causing a headache because since the LEDs ran much cooler than their incandescent forebears they weren't able to melt snow off like they used to, necessitating cleaner crews to go around and unblock the lights.

(Possibly apocryphal?)
posted by faceattack at 3:42 PM on February 4


Does anybody know if, in the course of swapping out the lights, there are any cities that are planning to also install deflectors to keep the light directed strictly downward?

The LED streetlight designs I've seen are a grid of emitters set into mirrored reflectors in a flat, oblong paddle - it's a flat surface beaming down light, rather than a globe or half-globe radiating it. An image search for "LED streetlight" indicates this is typical of the breed.
posted by Slap*Happy at 5:34 AM on February 5


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