Blinding headlights: See why high-tech headlights seem too bright
3:50

Blinding headlights: See why high-tech headlights seem too bright

Roadshow
[MUSIC] Hey folks, Cooley here, with some more of your emails about high-tech cars and modern driving. Not just emails but hatred. Hatred for modern headlights. I've done a lot of these lately. I think this one sums it up well. From Eric S in Orange County, California Who says, how are LED headlights even legal in the US? They are great when your car has them for the clarity, but seen when a car with them is behind me or approaching me I always think they have their high beams on. I've gone a lot of these kind of emails there like for folks that are having a visual reaction to modern, brighter, different color and different technology headlights. Now all of this is governed, very detailed by the FMVSS Section 108 which is this federal bible that tells car makers exactly what lights have to be like. How bright they can be, where they can be positioned, how high, how low, what their beam throw is, their beam pattern, and how to measure it. So that's all there. You'd say, okay well if that's all so specific, why do so many cars' headlights look so wildly different, especially lately. Because there are four technical parts in your headlight that can really change the nature of how you perceive the light from it. Let's run them down. First you've got the lens, that's the clear front of a headlight module. Sometimes it is clear. Sometimes it has a dimpled pattern to aiding beam forming in dispersion. So that changes things. The light source? Do you have a bulb? Do you have a gas discharge unit? That's one of those HID Xenon types of bulbs. Is it LED like Eric mentioned? That's relatively rare these days. Or is it super exotic? Is it one of the few high end cars that have a laser source? For the light the you've got the position of where the light is because there is some leeway in Federal law and where that bulb its and how it angles off the reflector that will be different for high beam and low beam. You've got the reflector itself the back part which is typically very polished that reflects forward but there is also often a forward reflector. In front of the bulb that shines back to the rear reflector that then sends the light back out To the road. That's a complex little dance. And finally, projector bulbs have a shutter. You'll see when a car that has these is turned on, you'll see it align and calibrate itself. The shutter comes up and sits at a cutoff. It's a dead giveaway right there. And that affects the nature of the beam, whether it's high or low. So look at all those parts and you can see, cars are not gonna look the same. Even if they have a similar core technology for their light source. It's not just about whether they got LED or not. Now the other thing going on is a lot of modern cars are trending their light frequency, the wavelength more toward blue. Blue is much more the color of the sun even though we think of it as being this big orange happy yellow orb, it's actually kind of a blue light source in our visible spectrum. That is kind of an upsetting color of light to see at night. We're not really adapted to see bright sunlight coming at us in spots during a nighttime dark scene. So it can be very hard for us to have the dynamic range in our eyes to reconcile a dark night with basically sunlight coming at as from the face of a car. That's why the older, yellower lights were a little easier to deal with. They were just kind of less potent, to be honest. and didn't demand as much of our ability to reconcile all that light out there and the wildcard to all of this, is DIY install. A lot of people are going out there and they're adding these high density discharge Xeon gas retrofit kits. They're very bright, they're not expensive kit. They tend to work okay... I'm not a big fan The big problem is, these were not designed by the car maker to work with the reflectors, to work with the lens, to work with all those different parts, and positioning. So it's kinda like saying, my photograph's out of focus, let me throw more light on it. You're kinda mixing metaphors, and mixing techniques there. [SOUND]

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