The LED headlight thread

The_Vermonster

Well-known member
Multiple surgeries have resulted in a loss of most peripheral vision. Peripheral vision is responsible for your night vision. So combine poor night vision with the increase in lights casting massive glare, and you have someone who is blinded with every passing car.

Driving a newer F150 is better than most vehicles because you sit out of the way of most glare. But the retrofit bulbs are still a problem. You can spot them from a mile away in a line of traffic.
Because she needs brighter lights or because the lights on the road are too bright?
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NPT90

Well-known member
Multiple surgeries have resulted in a loss of most peripheral vision. Peripheral vision is responsible for your night vision. So combine poor night vision with the increase in lights casting massive glare, and you have someone who is blinded with every passing car.

Driving a newer F150 is better than most vehicles because you sit out of the way of most glare. But the retrofit bulbs are still a problem. You can spot them from a mile away in a line of traffic.

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That is awful. I briefly suffered from temporary amblyopia (lazy eye) after a pretty terrible ailment. I ended up having to drive with an eye patch on at night in order to prevent blindness from oncoming traffic (I found myself closing one eye in order to see). I did find that a tinted windshield/all glass helped immensely in reducing glare from other vehicles at night (20% sides, 30% front). Certainly illegal but if you have a medical reason you can sidestep the regulations.
 

Red90

Well-known member
I have been looking for a solution to my wife not being able to drive at night for the past 6 years.
So combine poor night vision with the increase in lights casting massive glare, and you have someone who is blinded with every passing car.
If the problem is other drivers with illegal or poorly aimed lights, I'm confused how you are planning to find a solution by researching what lights to use in your own vehicle.
 

NPT90

Well-known member
If the problem is other drivers with illegal or poorly aimed lights, I'm confused how you are planning to find a solution by researching what lights to use in your own vehicle.
Seems to me he is both researching better lighting options for his own vehicle while dissuading folks from adding to a growing problem.
 

The_Vermonster

Well-known member
If the problem is other drivers with illegal or poorly aimed lights, I'm confused how you are planning to find a solution by researching what lights to use in your own vehicle.
I mean it's pretty straight forward. You can only make your headlights so bright. At a certain point you rely on other people on the road being respectful. That's just a general fact of driving. You do everything you can, but will always run into limits.

6 Years ago, the main issue was luxury SUVs. Now, everyone seems to be retrofitting older cars because they too can't see.

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pmatusov

Founding Member
No, that's pretty much most of it.

There's an issue of brightness temperature.
Most bulb manufacturers claim that the Sun is around 6000k, and we're used to that, so the bulb's brightness temperature should be as high as possible.

Now, bear with me for a while. Pardon me if you know all of this from the high school AP physics or elsewhere.

When/wherever there are particles scattering the light, light gets scattered, and depending on average size of the particles, different parts of the spectrum get scattered differently.

For instance, dust particles are much larger than visible light's wavelength, and the light experiences what is called Mie scattering. The fraction of light that gets scattered back doesn't depend on the wavelength and only depends on how large the particles are.

In fog, however, the water droplets are much smaller than the light wavelength, and this is termed Rayleigh scattering. The fraction of light that gets scattered (back and elsewhere) is proportional to the fourth power of the wavelength.

This is the cause of the sky to be blue, and this is the cause of the sun disk color temperature being actually lower (it does look yellowish, doesn't it?).

The ballpark wavelength of the blue color of visible spectrum is 450 nanometers, and the red - about 700. It means that in a fog, the most-reddish components of light will travel about 5.9 times further than blue. Curiously enough, red traffic light will appear red, yellow - somewhat reddish, and green - somewhat yellowish, which has been attributed to the initial choice of colors (that I have not been able to verify).

There are consequences to that:
(a) the light getting back to you from what you want to see on the road will also be scattered differently: the red-most components will propagate about 5.9 times further than blue-most. Between the losses back and fourth, it makes for an astonishing factor of 34 in difference in the amount of light you get back into your eyes.

(b) it gets worse: the glare back from the fog will be heavily biased towards blue part of the spectrum. So the bluer your lights are, the more heavily you are blinded by your own lights, and the less light you get from the objects on the road.

(c) the "other party" watching you from afar will also see more of the red light and less of blue light. It can be both a good thing and a bad thing.

That kind of leads to an obvious observation - that the "old-school" foglights were always amber, on the reddish side of yellow. As you may also know, in France for decades the headlights HAD TO be yellow. But the roads got better and this somehow faded away, and most of today's foglights are a fashion accessory.

To round it up:
LED lights are neither blue nor red, but on average their brightness temperature (and relative fraction of blue) is higher than halogens.
It makes no difference or makes it even better in dusty conditions (desert races), but it makes it a lot worse in fog.
Pick your poison.
 

Red90

Well-known member
....while dissuading folks from adding to a growing problem.
Well, that is a waste of time. The people buying $30 LED bulbs on Amazon don't care.

Personally I find the worst light are the OEM HIDs. They are stupidly bright and when out of adjustment burn the retinas out of your head.
 

NPT90

Well-known member
I am not 100% sure why that is relevant but thank you for putting it together.

I wear my polarized sunglasses in daylight fog and can actually see better due to the glare reduction. Honestly a good window tint (I have found) helps the most with the backlighting phenomenon you have described here in detail. I cannot cite any empirical data on various color temperatures and light transmission in fog.

Furthermore I have not noticed that having a brighter LED actually helps to illuminate road markers through fog vs my halogens.
 

pmatusov

Founding Member
I am not 100% sure why that is relevant but thank you for putting it together.
Just wanted make an argument for lower-color-temperature lights, of whatever design.

Tint on the windshield is illegal in California except for the top strip, which you really don't care for at night.
 

The_Vermonster

Well-known member
Well, that is a waste of time. The people buying $30 LED bulbs on Amazon don't care.

Personally I find the worst light are the OEM HIDs. They are stupidly bright and when out of adjustment burn the retinas out of your head.
The conversation comes up a lot in the Subaru community. You'd be surprised at the number of people willing to listen. But, how shall I say, there is one in every group. Most times, you can't change minds. But you put the info out there and let people make their own decisions. I think most make the right choice, and the few that don't didn't care in the first place.

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Red90

Well-known member
Yes, so you have maybe affected 20 people. Only 100 million more to go. Good luck on your quest.
 

The_Vermonster

Well-known member
Yes, so you have maybe affected 20 people. Only 100 million more to go. Good luck on your quest.
Thanks for the encouragement. Imagine how much easier it would be if there wasn't so much misinformation out there.

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RBBailey

Well-known member
Callsign: KF7KFZ
Just wanted make an argument for lower-color-temperature lights, of whatever design.

Tint on the windshield is illegal in California except for the top strip, which you really don't care for at night.
I thought you were making the argument for warmer lights -- higher color temps. Now I need to go re-read.
 

Red90

Well-known member
I thought you were making the argument for warmer lights -- higher color temps. Now I need to go re-read.
You have that backwards. Warmer colors (more yellow) are low temperatures. Cooler lights (more blue) are higher temperatures.
 

RBBailey

Well-known member
Callsign: KF7KFZ
All this time I thought 3500 was bluer, cooler, than 6000, warmer, redder? Huh.

EDIT: Oh, yeah, I'm always thinking of it through the camera. Just dawned on me.
 
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pmatusov

Founding Member
All this time I thought 3500 was bluer, cooler, than 6000, warmer, redder? Huh.

EDIT: Oh, yeah, I'm always thinking of it through the camera. Just dawned on me.
Ben, the meaning of "cool" and "warm" are the same, photography or lighting. What is "perceived" or misnamed as cool has higher color temperature.
 

RBBailey

Well-known member
Callsign: KF7KFZ
I'm referring only to the numbers assigned to cool vs. warm. In camera, when you dial in a low number, the image becomes blue. That's why I had confused cool/blue with a low number.
 
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