this post was submitted on 24 Aug 2025
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LED headlights are cool though (infosec.pub)
submitted 3 months ago by ThatGuyNamedZeus@feddit.org to c/flashlight@lemmy.world
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But only if they're regulated well

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[–] Rhaedas@fedia.io 24 points 3 months ago (3 children)

I'd almost accept the brightness of LED headlights if there would be a solution to the high beams. I don't know if there's auto high beams that don't work as designed, or people are idiots and just leave the lights in high all the time, or what. But when I have to avoid the light in my autodimming mirrors because it's still too bright, and the glare from THEIR lights is making the road signs in front of me hard to look at...

Light usage in general on cars these days is ridiculous. No one thinks about the other drivers, even when they see someone else doing the same thing they are. And no headlights in the dark? Are they insane?

[–] over_clox@lemmy.world 21 points 3 months ago (1 children)

A literally large issue that adds to the problem, especially in the USA, are the ridiculously large and tall trucks out there now. Even low beams on those can and will easily blind drivers of smaller vehicles, both from in front and even behind.

[–] Ulrich@feddit.org 8 points 3 months ago

Exactly. You have to consider the angles when your lights are 6 feet in the air. In order to not blind the car in front of you, you have to point them down. But then that also impairs your forward visibility. So fuck the person in front of you.

[–] grue@lemmy.world 4 points 3 months ago (2 children)

IMO part of the problem is unlit freeways: technically, people ought to be using their high beams on those roads because the speed limits are too high to have time to react with the short reach of regular beams, but they can't do so in practice because of blinding the other drivers around them. The only good solutions are lowering speed limits or pulling a Belgium and lighting the entire road network.

[–] Onomatopoeia@lemmy.cafe 4 points 3 months ago

Depends on where you are.

East coast? Plenty of light, mostly, because it is lit, and so many other cars you can easily see them.

I70, anywhere, same thing - so busy you're never alone.

I've rarely had this concern, and I've driven all over the country. I've occasionally thrown my high beams on, but modern headlights are already so much better than good old incandescents that it's a minor thing.

Plus, to quote one of my favorite characters "Honey, I never drive faster than I can see".

[–] dual_sport_dork@lemmy.world 2 points 3 months ago* (last edited 3 months ago)

or people are idiots and just leave the lights in high all the time, or what.

It's that one. Partially, anyway.

I'll quote James May, in context for once:

The local attitude to headlights seems to be full beams, or off.

I went to the hardware store after dusk the other night (Hey, Lowes closes at 10:00 PM) and on a short ~2 mile drive I counted nine oncoming cars coming at traffic with their high beams on. Nine. I flashed all of them and only one of them comprehended and turned them off. People are absolutely clueless, and that's not even counting the morons who have one low beam bulb burned out so they deliberately drive around with their brights on all the time rather than replace that bulb, so they "don't get a ticket." News flash, dummy: If a cop notices you actually two tickets. Even if you pay Autozone prices, a bulb is cheaper...

So yes, much of it is a people problem. Another people problem is that a lot of twerps just buy the cheapest LED retrofit modules from Amazon which don't provide the correct beam pattern from the reflector headlight assemblies in whatever their clapped out hoopty is. Versions totally do exist that work properly, but they cost $10 more so nobody buys them. Except me, apparently. (Except except, I deliberately have flagrantly illegal unaimed, high powered modules in my high beam sockets expressly for the purposes of lightly crisping anyone who deserves it. I really don't have occasion to use my high beams otherwise.)

I see a lot of people in my area with no lights on at all after dark, and it definitely is an increasing number compared to previous years. This isn't just a crotchety old man thing, either. People's driving habits got really bad during COVID and never rebounded back to even their previous level of general incompetence (already a low bar) afterwards.

[–] over_clox@lemmy.world 9 points 3 months ago* (last edited 3 months ago) (3 children)

My main question is..

Why don't they diffuse the light? Why is it basically a mostly straight beam forward? Whatever happened to light diffusion?

I've actually tested this on a couple matching plain white LEDs, by sanding one down to have a somewhat rough diffusion surface. Guess what? The light spreads much more evenly!

This could easily be scaled up in headlight factories with a sandblaster...

Edit for example post: https://lemmy.world/post/34975418

[–] thejml@sh.itjust.works 12 points 3 months ago (2 children)

They're supposed to, per NHTSA regulations, be bright below and dim but diffused above, and drop off at a determined slope and such. This is super obvious if you park a new car in front of a garage door or wall and turn on the lights.

The brights tend to be diffused to be bright all over and thus illuminating curves and the areas higher above the road. It would be absolutely horrible if the whole brightness of the light was diffused as you would be blinding oncoming traffic. Its fairly close to what you see with thr brights, though.

In Europe they have higher tech versions that haven't been approved for US consumption yet that can sense oncoming traffic and turn off individual areas of the lights to further prevent blinding oncoming traffic.

As another poster said, part of it is the jacked up SUV behind that illuminates level of his lights and below, where I am, with the ferocity of the Sun.

[–] over_clox@lemmy.world 4 points 3 months ago* (last edited 3 months ago) (1 children)

You must not be from the USA then, or must not ever drive at night.

Sadly, the USA apparently ignores common sense standards now, even on brand new unmodified vehicles.

[–] thejml@sh.itjust.works 5 points 3 months ago (1 children)

Sadly, I'm 100% in the US and have looked into the standards a bit since I have to deal with it all the time. Regular inspections are required where I'm at and they're picky as crap about the whole light cut-off and drop/distance aim requirements. It just doesn't matter because people turn on their brights instead or have much higher vehicles than my sedan.

[–] over_clox@lemmy.world 4 points 3 months ago

You have vehicle inspections? That's still a thing in the USA?

Sigh, just send me right down the rabbit hole why don't ya?

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

I'm in Mississippi if that counts for much.

[–] x00z@lemmy.world 0 points 3 months ago

It's awful in the EU too.

[–] XeroxCool@lemmy.world 3 points 3 months ago (2 children)

Oh, your proposal is to diffuse the light? No, that's how you end up blinding everyone ahead of you instead of just those that happen to be below your "cutoff". The point of a low beam is to give as much light as possible to the road ahead of you without shining into anyone's eyes. High beams have a less-defined blob of light extending upwards. Diffusing a low beam makes everything worse. If you want an example, just look at any older car with hazy headlights. They're blinding other drivers and reducing their distance/throw.

[–] over_clox@lemmy.world 1 points 3 months ago (1 children)

Also, we happen to have an older vehicle with mix and match headlights. The hazy headlight is the one that doesn't blind anyone.

Then again, I begin to assume you've never adjusted headlights before.. I have.

[–] XeroxCool@lemmy.world 1 points 3 months ago (3 children)

Then again, I begin to assume you've never adjusted headlights before.. I have.

I've been in the projector retrofit world for 15 years, going back before threaded shaft mounts, back on hidplanet, back before photobucket decimated forums. At no point is a diffuser the answer to a better headlight. 2000lm aimed wrong is blinding whether it's from a penlight or a paper-sized diffuser. Try going full dark adapted and looking at a full moon. It hurts. And that's a light source only worth 1cd on the ground around you.

If you can't recognize how much poorer your hazy headlight is for distance, you aren't solving the headlight problem. You claim to know how to aim a headlight properly, yet the hazy headlight isn't even giving you a proper beam pattern on the wall to aim. And actually, why is the clear headlight blinding people when you claim to know how to aim th properly?

[–] over_clox@lemmy.world 1 points 3 months ago* (last edited 3 months ago) (1 children)

It's not just about distance, it's also about not blinding the person or deer in front of you..

Bright lights are fantastic! As long as you're the only vehicle on the road...

[–] XeroxCool@lemmy.world 0 points 3 months ago (1 children)

I have no idea what point you're trying to make anymore. If your headlights have a clean cutoff, meaning light is not spilling upwards above the low beam's hot spot, and they're aimed properly, you're not blinding anyone unless you're both peaking a hill. Any lights blinding you are either aimed wrong or something is wrecking the proper optics - hazy lens, wrong bulb type, damage, etc.

Why are you a proponent of spilling light sideways outside of your usable area? Even fog lights, with their very wide beam, are useless at highway speeds. Anything they illuminate outside the standard low beam is outside of what you can run into typically and is much too close to react to.

I have no idea why you're bringing the Haynes/Chilton manuals into this. Every car gets an owners manual.

I assume you're just trolling now. Good night.

[–] over_clox@lemmy.world 1 points 3 months ago (1 children)

Do you know how tall a 1994 Nissan Sentra is?

Do you know how tall a modern Ford F150 is?

Do you realize that the headlights on the F150 are actually higher than the windshield on the Sentra?

Even properly aligned, headlights be blinding people, especially people in smaller cars. So I guess the 'proper' solution is to just scrap my mom's car and pull a brand new F150 out of my ass so she can drive at the same height as the rest of the ~~tanks~~ trucks on the road huh?

https://youtube.com/watch?v=w0nBlZwUT3s

[–] XeroxCool@lemmy.world 0 points 3 months ago (1 children)

Headlight height has nothing to do with this conversation. Frosting the headlights on an F-150 will reduce their throw. The F-150's headlights will be made brighter to compensate. Your Sentra will now be blinded all the same. The solution to this problem is lowering headlights in the type of the Juke and Gen 1 Cherokee (not grand Cherokee, the 2015 compact).

Your sentra's hazy headlight is throwing more light at oncoming drivers than the clear, properly aimed headlight.

[–] over_clox@lemmy.world 1 points 3 months ago* (last edited 3 months ago)

Again and again, I've already said multiple times, I do not mean to haze the front of the headlight, I mean to diffuse the back reflector

Definitely have the front clear and no haze, no dispute there. But if you shine the light towards a backside diffused reflector, then if designed properly, the light coming out of the front will be fully directionally controlled, while also being smoother and using the front surface area more effectively. And most importantly, not blinding other drivers!

[–] Zak@lemmy.world 1 points 3 months ago* (last edited 3 months ago) (1 children)

Try going full dark adapted and looking at a full moon. It hurts. And that’s a light source only worth 1cd on the ground around you.

I think you mean lux, not candela. A common estimate is that the full moon is about 0.25 lux, though it can vary considerably. The moon's intensity is a bit higher than 1cd; putting 0.25lux on Earth from 384400km away requires 36940840000000000cd.

That's not to take away from your point; a well-aimed, focused light source with good cutoffs won't blind people nearly as much as a diffused one will.

[–] XeroxCool@lemmy.world 1 points 3 months ago

You are correct, lux, not candela. Got my alternate light measurements mixed up. Guess I was also off by an order of magnitude for it's lux when full. Look, I can read paper under moonlight!

[–] over_clox@lemmy.world 1 points 3 months ago

That's just it, it's not just about you. It's also about oncoming drivers in the other lane..

[–] over_clox@lemmy.world -1 points 3 months ago* (last edited 3 months ago)

You clearly don't understand light diffusion then.

If your light bulb is say 10cm², and all mostly pointing forward through a 100cm² clear plastic or glass like a laser, then the oncoming driver is basically either looking at a laser, or looking away.

But if you evenly diffuse that 10cm² light through the 100cm² lens, then the light is much more even and smooth, equal lighting from the same light, gives good vision to the driver, and doesn't blind oncoming drivers.

Edit: Yes I just pulled simple numbers out of my ass for simplicity, but the basic fact holds true, that if all the lumens point one way, they're gonna blind oncoming drivers.

But if you diffuse that same light energy evenly across a good broad angle range (let's say around 60⁰ or so), then the light illuminates evenly, and isn't like shining a laser light at an airplane...

Also, just a friendly reminder, it's illegal to shine lasers at aircraft, so why would anyone support or approve of that on the roads?

[–] Ulrich@feddit.org 2 points 3 months ago (1 children)

That would make them worse, not better.

[–] over_clox@lemmy.world 0 points 3 months ago (1 children)

Please explain, with scientific detail.

Spread the same light out evenly, instead of laser light focus that burns the retinas of oncoming drivers and forces oncoming drivers to look away..

Please explain how diffuse is worse than laser?

There's a reason lasers are against federal aviation law, they blind pilots. What makes laser LED's safe for road vehicles?

[–] Ulrich@feddit.org 2 points 3 months ago (2 children)

Lasers don't hurt anyone unless you shine them directly into someone's eyeholes. Modern LEDs and their housings are designed to point at the road, not your eyes. Diffusing them would move more of that light into your eyes.

[–] ArcaneSlime@lemmy.dbzer0.com 1 points 3 months ago (2 children)

Modern LEDs and their housings are designed to point at the road,

Ahh shit what was the key to doubt again?

Ah here it is X

If that's the case why do 90% of them point directly in my eyes? Is "modern" like '24+?

[–] luppano@lou.lt 2 points 3 months ago (1 children)

@ArcaneSlime @Ulrich They are not pointed directly at your eyes, it would be much worse. But they are significantly brighter than previous headlight technologies, and often have smaller reflectors, or lenses, resulting in a smaller (and even brighter) apparent light source. This concentrated apparent source of light more easily causes glare on windshields, glasses or simply our eyes transparents parts. It is awful and very poor design. Not mentionning blue/cold light scatters MUCH more anyway.

[–] luppano@lou.lt 1 points 3 months ago (1 children)

@ArcaneSlime @Ulrich (Blue light scattering in everything is why the sky is blue)
Also, the worst part imho (thankfully less common) is the use of random LED drop-ins in old housings absolutely not made for their light source shape, position or brightness, scattering light in every direction, without even throwing light farther than stock halogen bulbs.

[–] ArcaneSlime@lemmy.dbzer0.com 1 points 3 months ago (1 children)

@Ulrich

I'll just reply to both of you at once: Well no matter what it is, the IRL effect is light pointing directly in my eyes.

[–] luppano@lou.lt 0 points 3 months ago (1 children)

@ArcaneSlime Well, everything you see is light directly pointing in your eyes.

[–] ArcaneSlime@lemmy.dbzer0.com 1 points 3 months ago

....aight that's fair lmao

[–] Ulrich@feddit.org 0 points 3 months ago* (last edited 3 months ago)

They don't point directly at your eyes. A small portion will reach your eyes because your eyes are at the same level as the road ahead so there needs to be some spill.

The most modern headlights can actually turn off just the portion that's pointed at you, but it's been a legal hellscape trying to get those approved for road use in the US for some reason. I actually have them in my car but they only work in Europe.

This condition is greatly exacerbated by the soccer Mom Tonka trucks with headlights 6 feet in the fucking air.

[–] over_clox@lemmy.world -1 points 3 months ago (1 children)

I gather you have absolutely no experience driving at night then.

[–] Ulrich@feddit.org 0 points 3 months ago (1 children)

Ah yes, more insults and no arguments. Goodbye.

[–] over_clox@lemmy.world 2 points 3 months ago* (last edited 3 months ago) (1 children)

Sadly, here in the USA, most newer trucks and SUVs have hoods so tall and headlights so high up that they're basically eye level with an average standing grown adult, and stupid bright no less. I don't know why they even allow such large passenger vehicles or such unnecessarily bright lights on the road here, but they do.

Now that might be okay if everyone was driving around an 8 foot tall tank, but try driving around in my mom's barely 4 foot tall sedan. Even those 'properly' adjusted headlights are still way too high up and shining right in your eyes.

And it's become a big problem in the USA...

https://youtube.com/watch?v=w0nBlZwUT3s

[–] Ulrich@feddit.org 0 points 3 months ago* (last edited 3 months ago) (1 children)

I agree but none of that has to do with LEDs or diffusion. Diffusion won't make a truck's headlights lower to the ground, it will just cause more light to go into your eyes, like I said.

[–] over_clox@lemmy.world 1 points 3 months ago* (last edited 3 months ago) (1 children)

No, you're misunderstanding the concept of proper diffusion for the application. Rather than have most of the light coming from the centralized source, spread it backwards towards a diffused reflector. Of course design things at appropriate angles and stuff though.

Same amount of light, but spread out much more evenly and not burning a hole in people's retinas. Just as a simple hypothetical test example (obviously a quick hack test, not suitable for actual road use)..

Have someone stand in front of a vehicle with the headlights on. They'll be basically and rather quickly blinded and have to close their eyes or turn their head.

Now do the same test, but with a piece of white paper covering the lens. Now that will diffuse the light, and the person observing won't be staring directly at the bulb, but will effectively see the same amount of light, just spread out more evenly.

Now design the diffusion principle into the reflector behind the bulb, make it where nobody has to directly see the bulb itself, but the controlled and directed diffused lighting from the back reflection.

There's no reason that oncoming drivers have to directly see the core center of the bulb when we've had light spreading technology for ages. Spread that light out to more effectively use the full surface area of the front face of the whole headlight assembly.

And no the light doesn't have to go everywhere, I get that. That's why I mean for the back reflector surface of the headlight to do the diffusion, so as to control and spread out the emitted light more smoothly.

Or, ya know, make the headlights at a standardized height at sensible brightness and appropriate angles. I say headlights (and the hood itself) should generally be no higher than half the average standing adult height. Sigh, that ship done sailed though, the roads are slap full of vehicles way taller than they need to be...

[–] Ulrich@feddit.org 0 points 3 months ago (2 children)

Rather than have most of the light coming from the centralized source, spread it backwards towards a diffused reflector.

It doesn't matter which direction it goes.

Same amount of light, but spread out much more evenly

You don't want your light to be spread out. You want it concentrated to where it needs to be and redirected away from where it doesn't need to be (including people's eyeholes).

Have someone stand in front of a vehicle with the headlights on. They'll be...blinded

If you have this problem then your headlights are not adjusted properly. That should not happen.

Now do the same test, but with a piece of white paper covering the lens. Now that will diffuse the light

You're not talking about diffusion, you're talking about obstruction. Do that and now the driver can't see shit and ya might as well just not have them.

There's no reason that oncoming drivers have to directly see the core center of the bulb

They don't.

headlights...should generally be no higher than half the average standing adult height.

They shouldn't even be that high. But once again, that's a separate problem.

[–] over_clox@lemmy.world 1 points 3 months ago

Also, putting white paper in front of the lens isn't the perfect example, which I already said is a quick hack demo anyways. I get that would be a partial obstruction, but that also reflects a lot of the light back in randomly, which gets reflected back out randomly.

Kinda similar, but reverse, of how true lasers work. Back and forth reflection, eventually most of the light escapes, just in my hack test example it scatters everywhere, rather than in one direction.

There's plenty enough knowledge and technology in illumination that there should be no reason for such large headlight assemblies to be shooting out all that light from something about the size of a postit...

[–] over_clox@lemmy.world 1 points 3 months ago

Okay, then have someone sit in front of the vehicle..

Guess what position people drive in? Sitting!

Anyways, I found these very relevant videos...

https://www.youtube.com/watch?v=rKhRA0q-ZUM

https://www.youtube.com/watch?v=DBWi0k_271I

Note that on the second video, about 18 seconds or so in, they show what I mean about staring into the core center of the bulb, they reflect the light through a fairly small magnifying lens, not much bigger than a postit note.

Why oh why reduce the surface area of the source of light emission so small, when the front of the headlight has so much more practical surface area to distribute the light more evenly? That only exasperates the problem by using a magnifying lens like that.