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Comment by 60654 | Hacker News Reader

I've been watching some of the neighborhoods undergo early adoption of LED street lamps. It's been interesting.

The new lamps are definitely much bluer than the current sodium lights, which gives the street a different, unfamiliar feel. The article suggests the city ultimately adopted 3000K lamps, but it definitely feels like the pilot program used 4000K ones, they looked very cool.

Another interesting development with these so-called "smart lights" [1] is that the city can potentially modulate brightness on a street-by-street basis, and asking different neighborhoods to weigh in on where they want the lamps to be brighter (or maybe, if they want them dimmer on side streets etc). This sounds like a very good change - customizing street lights based on neighborhood requirements is a very nice development!

[1] https://www.cityofchicago.org/city/en/depts/cdot/supp_info/c...

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All color considerations aside, one thing I find quit discomforting (first subconsciously, until I put my finger on it, and now even worse) is that led lights are very very often a rectangular array of lighting elements. So instead of a point (or at least a large diffuse, continuous "point" in various bulb constructions) there are between 25-64 points of light in a 6"x6" area. From a 20' light pole, looking at the shadow of your hand on the sidewalk, you see (let's say) 36 different vague shadows, in a rectangular array, with a disfigured hand shaped, darkest shadow in the middle where the shadows all overlap. Truly, it can be dizzying if you try to focus on the shape of the shadow from a single object. Tree canopies become shifting fields, everything gets a blocky 16bit feel to it. I'm only human, but I can imagine some animals are well tuned to single point shadows and this effect might really throw them off.

(Interesting aside, I first noticed this while leaving LACMA (LA County Museum of Art) where the pure Instagram gold of Chris Burden's collection of old LA street lamps tightly packed, produces the same effect)

Does it differ too much from vague shadows on an overcast day? I'd say 64 close-by shadows look more natural than more distinct 4, which I could clearly see with regular point-source lamps on tall poles.

Presumably this can be ameliorated by refracting the light with a plastic screen?

Yes, those shadows[1] are weird and feels a bit like low res shadow maps in games. Hopefully they start using diffusers in the future.

[1] https://pbs.twimg.com/media/CIUkuDmUcAAqiF7.jpg

But AFAIK LED brightness is usually controlled by pulse-width modulation, which is essentially adding flicker.

There are people with flicker sensitivity that have headaches when exposed to flickering light. A link to a HN discussion that touched the problem of PWM and flicker in the comments: https://news.ycombinator.com/item?id=13330611

There's no reason to use a low-frequency carrier for PWM. Drive the LED at a multi-kHz speed and it's fine.

In my subdivision in a metro Atlanta county I the local power cooperative is replacing failed halogen/sodium/etc street lamps with LED.

The orange lights provided good light but the same pole with a LED now lights up the area as if it were full moon or close to it. You cannot look directly at these lights where you could at the older lights. I have an orange lamp in the corner of my lot but the nearest LED is about three hundred feet away and it still puts out more.

One oddity which I cannot completely attribute to the lights. Birds in our holly bushes were singing at very odd hours for the first weeks or two but have apparently moved to bushes and trees in the back yard.

I wonder what the effects on other animals will be. Maybe this is the thing thats killing the honeybees.

Ok probably not, but if humans can be out of whack from this, I wonder what other creatures will start to lose sleep - or will nocturnal animals sleep in all night?

I'd be interested to know what the effects on bugs, and animals that feed on bugs, will be.

Will the new lights attract more bugs? Will animals that feed on bugs be attracted to them?

Yea I live on a street with the pilot program and no doubt they were much brighter than 3000K. They were very blue but I really like them. It gave my neighborhood a more small town feel if that makes any sense.

3000K is about color not intensity

Not in perception, however.

Unfortunately, using "brighter" here is still completely incorrect and parent is right for correcting him.

I always perceive blue light as brighter. I dabble in indoor lighting, and warmer (bluer) bulbs always seem brighter. Unless the brightness of fluorescents changes with the color temperature, I'm inclined to agree with the original comment. Besides, nit picking is rarely useful.

There's actually a reason for that - bluer light reflects in front of the retina rather than focusing onto it, and so it scatters throughout the eye more than other wavelengths, especially when there's little ambient light. It's called the Purkinje effect.

The light doesn't have greater luminosity, but it is perceived as brighter.

https://en.wikipedia.org/wiki/Purkinje_effect

https://blog.codinghorror.com/blue-led-backlash/

Thank God you cleared that up.

Who is nitpicking here? My parent? Me? You?

We are all just trying to help someone be more correct. For me at least, it isn't because I wish to nit pick. Perhaps you could have had a more useful comment by not adding your personal anecdote and instead providing a citation?

The other responder to your comment is correct. It is entirely perceived and there is no real change in luminosity and thus brightness is the incorrect term.

I was offering my insight as both a graphic designer and amateur technical 3D artist with solid grasp of color theory and optics. Meanwhile you just butted in to tell me I'm wrong and I shouldn't tell other people they are wrong.

That's a conflicting position, and furthermore the person I was replying to was correcting someone else, and I was clarifying for both of them. So I really don't know why you felt the need to comment in the first place.

Either you're responding to the wrong person, or you did a very poor job at reading my comment. In case of the latter:

> Who is nitpicking here?

You and /u/colechristensen

> We are all just trying to help someone be more correct.

No one doubts the purity of your motives.

> The other responder to your comment is correct. It is entirely perceived and there is no real change in luminosity and thus brightness is the incorrect term.

No one disputes that the effect is perceived.

> I was offering my insight as both a graphic designer and amateur technical 3D artist with solid grasp of color theory and optics.

No one disputes your qualifications.

> Meanwhile you just butted in to tell me I'm wrong and I shouldn't tell other people they are wrong.

No one said you were wrong. I simply said that my experience is like that of /u/icelander and /u/pducks32 in that I perceive blue light to be brighter, which you disagreed with in your previous comment, but seem to agree with in this one. I didn't tell you not to correct other people, I said nit picking (i.e., correcting a minor discrepancy which isn't important, relevant, or otherwise causing confusion) is rarely helpful.

Interestingly, /u/Karunamon pointed us to the [Purkinje Effect][1] as an explanation for why blue light is perceived to be brighter, so perhaps you aren't correct despite your qualifications (I guess you espoused both sides of the argument, which would make you simultaneously correct and incorrect :p ). This certainly isn't my subject, so I'll leave you to sort it out on your own.

[1]: https://en.wikipedia.org/wiki/Purkinje_effect

Our sensitivity to light has no bearing on how bright it actually is.

You're going to great lengths to nitpick yourself, my friend. This is downright silly so I think I'm done. You're arguing just to argue. Feel free to have the last word.

I know sorry wasn't thinking.

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