Yellow Headlights: For Crazy Frenchmen Only?

[jaudette3]

Complete post with pictures follows.

[jaudette3]

Yellow Headlights: Purely Cosmetic or Functional?

Have you ever wondered if yellow (technically selective yellow that filters out blue, indigo and violet) headlights are purely cosmetic, if they actually have a function, or if they’re just a product of wacky Frenchmen? My uninformed impression is that they were mostly cosmetic while sacrificing some illumination. The answer, as it just about always is when you dig a bit, is more complex.

They possibly improve nighttime visibility under some conditions without sacrificing much brightness. There is an approximately 12% loss of light which many would find affordable given the brightness of today’s headlights, especially the high performance H4 bulbs and LED’s. On the plus side, there is a gain in visibility in inclement, hazy or foggy weather. The technical reason is that the selective yellow removes blue to violet colors from the wavelength spectrum that can cause difficulty for human eyes to process, which reduces what we think of as reflection.



On the color spectrum yellow light has a longer wavelength than blue to violet colors. Shorter wavelengths are harder for the human eye to see and tend to focus in front of the retina. In inclement weather, the yellow headlight filters out filtering out blue and the like, so there is less of that light produced to be reflected back from rain, fog or snow. So there is less perception of glare.



Most LED headlights measure in the 4000 Kelvins area while yellow headlights are in the 3000 or a bit less area. Interestingly, LED headlights with yellow lenses emit a light fairly close to the warm light we are used to seeing from older headlights.

It all depends on your environment and most common prevailing conditions. If you live in an area with frequent fog, rain, snow, dust or smog, it might be worth considering yellow headlights.

If you would *really* like to dig down into this lighting guru Danial Stern has an amazing article about selective yellow lighting.

[Harpo]

I just think they look cool but only with blue cars

[jimmyjimmy]

I just know that in the sixties when I was a little boy here in Europe Peugeot and Citroen started with those amber head lights in their cars.My father told me that they were better for night driving...Whole his life he drove citroen.
I still drive a 2cv but with normal lights.I believe these amber lights are even prohibited at the MoT.

[jaudette3]

Selective yellow headlights were mandated in France until the EU made them use clear lenses. One story is that the law for yellow headlights was enacted in the mid-1930's because of WWII. The yellow headlights made it easy to distinguish which cars were French and which cars were not.

Has anyone noticed that I used the term "Crazy Frenchmen" and there's been no blow back? The French are one of the few areas where it's not necessary to be politically correct. And with the name Jean-Paul Audette I get a pass anyway.

[Jonny H]

I run yellow lenses on my SC. Originally, I put them on as a little French twist to go to Classic Lemans a few years ago. Then when I went out at night I could not believe the improvement so I have kept them. The main benefit is the reduction of glare from road signs and other reflectors. Your eyes do not get as tired. 100% legal in the UK.


Ultra bright blue/white headlamps are the most stupid marketing exercise in the name of 'safety'. As the OP states, blue/white light produces far more glare than yellow/white. Yeah, they look cool and sell cars but they are not safer.

There is no evidence to suggest being able to see further down the road makes you safer. There is plenty of evidence to suggest that blinding oncoming traffic is outright dangerous.

[Jonny H]

Wikipedia - Selective Yellow

"The intent of selective yellow is to improve vision by removing short, blue to violet wavelengths from the projected light. These wavelengths are difficult for the human visual system to process properly, and they cause perceived dazzle and glare effects in rain, fog and snow.[7] Removing the blue-violet portion of a lamp's output to obtain selective yellow light can entail filter losses of around 15%,[8] though the effect of this reduction is said to be mitigated or countervailed by the increased visual acuity available with yellow rather than white light in bad weather.[7]

A research experiment done in the UK in 1968 using tungsten (non-halogen) lamps found that visual acuity is about 3% better with selective yellow headlamps than with white ones of equal intensity.[9] Research done in the Netherlands in 1976 concluded that yellow and white headlamps are equivalent as regards traffic safety, though yellow light causes less discomfort glare than white light."

[lada03]

I specifically was looking for french euro headlights for my mercedes diesel wagon

What a huge difference from the US spec 4 round headlights. I absolutely loved them

[nathanbs]

Originally Posted by Harpo

I just think they look cool but only with blue cars

I love on blue as well but also think it works on quite a few others. Stupid fog lamp is crooked lol

[spedrcr]

I find the yellow light to be easier on the eyes, especially in fog and other foul weather conditions. The best way I can describe using yellow light is that everything in front of you is lit up, but you just don't see the light being cast.

My yellow recipe is PIAA Ion Crystal bulbs through clear H4 lenses. Augmented with PIAA Super Blue H3 bulbs through yellow fog lenses.

Last name is French and my wife thinks I'm crazy...

[IS300]

I have posted this before... now seems good ....I like them!

[spedrcr]

Quick hijack/sidenote. IS300 what kind of side view mirrors are those on your wine red coupe?

[jaudette3]

@IS300

I like the yellow lenses on H1's. And another plus is that they look like the flat Bosch 4487 lenses, the best looking lenses that Porsche ever used. They don't have the protruding lip on top like H1 and H4 lenses that break up the smooth curves of the silhouette from the side.

[thsupernge]

Originally Posted by Jonny H

I run yellow lenses on my SC. Originally, I put them on as a little French twist to go to Classic Lemans a few years ago. Then when I went out at night I could not believe the improvement so I have kept them. The main benefit is the reduction of glare from road signs and other reflectors. Your eyes do not get as tired. 100% legal in the UK.


Ultra bright blue/white headlamps are the most stupid marketing exercise in the name of 'safety'. As the OP states, blue/white light produces far more glare than yellow/white. Yeah, they look cool and sell cars but they are not safer.

There is no evidence to suggest being able to see further down the road makes you safer. There is plenty of evidence to suggest that blinding oncoming traffic is outright dangerous.

Could not agree more. A few years back I came up on a highway patrol on a dark exit who had pulled someone over and I about drove off the offramp into a ditch because the lights had blinded me so badly. They're awful!

[IS300]

mirrors are from a 964... they do look cool in the photo

[IS300]

[MY911S]

Funny you posted this today John. Deciding which "yellow" lights to run on the Carrera. And on a slight digression the yellow fog lights on the 280SE came stock with the car.

[Larmo63]

Originally Posted by nathanbs

I love on blue as well but also think it works on quite a few others. Stupid fog lamp is crooked lol

LOVE the yellow lenses on this yellow car.

Also, this photo is convincing me to buy P7s for my wheels when they are done. Are you running 245s on the rear?

[proporsche]

Originally Posted by nathanbs

I love on blue as well but also think it works on quite a few others. Stupid fog lamp is crooked lol

very very nice looking yellow beast...
Ivan

[Flojo]

Originally Posted by Harpo

I just think they look cool but only with blue cars

I hear ya