Discussion: Are fog-lights really worth it?

When you buy a car, you have an option to have fog lamps. Would you choose them, or would you not? Do they really work, or do they not?

Fog lights must ONLY be used when there is heavy fog. Now... how often is there heavy fog?! Quite rarely. So is it worth it to pay $100s or maybe $1000s for fog-lights that are almost never used?

The majority of fog lights are used improperly. Most people use fog lights when they are not supposed to; more than when they don't use them when they are supposed to. Fog lights can actually be dangerous because they light up the foreground more, ruining your night vision with the brighter foreground and making it harder to see in the distance. And there's no use in seeing the ground closest to you because if you see something like a pothole that close, it's already too close and you can't avoid it. You need to see in the distance.

Discuss.

From what I've been told, fog lights are for OTHER people to see you, not to help you see, that's what your headlights are for.

Normally fog lights are of an amber color, which is easily seen through thick fog.

I only use my fogs when it is heavy fog, which is almost never since we're seeing a massive drought.
Haven't even seen fog in years.

If you live where there is enough fog, sure...they work for that. The vast majority of people use them to supplement their headlights and not for fog though, as many car headlights don't light the sides of the road well, so cornering, etc, is easier with fog lights.

Their best use is to show you the center stripe and fog line at the shoulder, and enough to not run into a stopped car in front of you, etc.

The problem is that they have them on all the time, so the pool of proximal light is brighter, and, they lose night vision adaptation, and, in total, ironically see less of what's out there.

They think they'll see deer about to run out onto the road...but, unless driving at the speed you'd be in in heavy fog (A few mph or less), they'd simply see the deer hit them, and not have time to avoid it.

Driving lights, for most people, make more sense than fog lights.

My wife's Mini Cooper had front and rear fog lights...and the front ones were to see the road, and the rear ones were so people behind you would see YOU.


I drive in low lying areas that DO fill with fog, and, its thick enough so that you really can't see with your low beams, they are aimed too high....and your high beams are REALLY aimed too high up.

I FIRST decided I needed fog lights on one stretch that was about a mile long, and took me about an hour...leaning out the door with a hand held search light at ~ road level to shine under the fog better, and sweeping it back and forth to see what was there. I turned my head lights OFF to see better, then on so others's could see me.

After adding fog lights, the same stretch was far less agonizing...10 minutes instead of an hour....to go ~ a mile.

And amber and white worked about the same. Blue is about invisible though, essentially useless.


If not mounted LOW, they don't really work, as they work best if the light is shining beneath the fog, so you see the road, etc, illuminated - but the fog itself is not glowing.

On my rigs that are built somewhat high up, the lowest point I could mount a fog light is too high for one to work, so, they have no fog lights.

MrJino said:

From what I've been told, fog lights are for OTHER people to see you, not to help you see, that's what your headlights are for.

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Many people are told many wrong things; this is among them. Proper fog lamps help you see the road edge and lane markings so you can safely keep your lane while creeping along.

Normally fog lights are of an amber color, which is easily seen through thick fog.

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Fog lamps can be white or selective yellow. Neither color is chosen for an advantage in conspicuity, nor for "fog penetration" or anything else. (Selective yellow does have certain advantages related to the human optical system, but a properly designed white fog lamp is fine.

"Amber" is a signalling color and is not used for fog lamps.

TEEJ said:

The vast majority of people use them to supplement their headlights and not for fog though, as many car headlights don't light the sides of the road well, so cornering, etc, is easier with fog lights.

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Indeed, many people misuse fog lamps. They shouldn't be lit in the absence of fog.

There are systems that will activate the fog lamp on the side being turned to, this is speed-limited and requires the turn signal to be on. It extinguishes the lamp when the turn is complete. (Fog lamps providing a cornering function *must* be white.)

The problem is that they have them on all the time, so the pool of proximal light is brighter, and, they lose night vision adaptation, and, in total, ironically see less of what's out there.

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Yep.

They think they'll see deer about to run out onto the road...but, unless driving at the speed you'd be in in heavy fog (A few mph or less), they'd simply see the deer hit them, and not have time to avoid it.

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Indeed. Misused fog lamps are GREAT at illuminating the thing you're just about to hit.

My wife's Mini Cooper had front and rear fog lights...and the front ones were to see the road, and the rear ones were so people behind you would see YOU.

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I always say that a rear fog lamp is designed to protect you from the guy behind you that has his front fog lamps on. Many people in Oklahoma seem to think fog lamps are magical and allow them to go 65mph in heavy fog.

Fog lights in US are a marketing thing mainly, and are associated with a higher-level trim of a car. Most importantly, there's a problem with how manufacturers design wiring for them. If you noticed, fog lights usually cannot be used without headlights being on at the same time. Meaning, they cannot be turned on along with just the sidemarkers.

This is an issue during thick fog. In such conditions, you want your light source to be as low as possible, because that's where the fog is thinnest. Having headlights on along with foglights in low conditions doesn't do much, because you get a lot of light bouncing back to you from your headlamps.

So for fog lights to be effective, they need to turn out independently of main driving lamps. Additionally, they work best when they are yellow in tint, as that color has the least scatter, which results in light bouncing back into your eyes.

ahtoxa11 said:

Fog lights in US are a marketing thing mainly, and are associated with a higher-level trim of a car. Most importantly, there's a problem with how manufacturers design wiring for them. If you noticed, fog lights usually cannot be used without headlights being on at the same time. Meaning, they cannot be turned on along with just the sidemarkers.

This is an issue during thick fog. In such conditions, you want your light source to be as low as possible, because that's where the fog is thinnest. Having headlights on along with foglights in low conditions doesn't do much, because you get a lot of light bouncing back to you from your headlamps.

So for fog lights to be effective, they need to turn out independently of main driving lamps. Additionally, they work best when they are yellow in tint, as that color has the least scatter, which results in light bouncing back into your eyes.

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For water vapor of the particle size that exists in fog, there is almost 0 difference in scatter for any wavelength in the visible spectrum. Longer wavelengths (no blue) create less glare perception, as well as impact the pupil less. There may be a bit of argument for improved contrast due to less scatter within the eye ... but not from optical effect outside the eye.

Semiman

If we made it law, that fog lights on new vehicles must be selective yellow.
Then they would become un-cool, and people would leave them off.

Wasn't it changed awhile back, so that you have to manually select fog lights every time you turn on the headlights [no more rotary ring so the fogs can default to on]

Yes, fog lights are no longer able to be turned on by default when the headlights come on. That's a good thing.

MrJino said:

From what I've been told, fog lights are for OTHER people to see you, not to help you see

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That is not at all correct.

Normally fog lights are of an amber color, which is easily seen through thick fog.

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Neither of the two halves of this statement are correct. In the first place, most fog lamps emit white light, though selective yellow is also permitted -- see here. In the second place, yellow or amber light is not easier to see through fog than white light.

I only use my fogs when it is heavy fog

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Good! You are using them right. Most people don't.

MichaelW said:

If we made it law, that fog lights on new vehicles must be selective yellow. Then they would become un-cool, and people would leave them off.

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I don't know about that. There seems to be a booming market in products designed to turn white fog lamps yellow. Yellow bulbs (of generally poor quality), yellow self-adhesive lens films, etc.

Wasn't it changed awhile back, so that you have to manually select fog lights every time you turn on the headlights [no more rotary ring so the fogs can default to on]

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Unfortunately, no such regulation exists in North America, and no such provision exists in the UN Regulations used pretty much everywhere else in the world. Automakers are free to configure their vehicles this way, but it's not required.

ahtoxa11 said:

Additionally, they work best when they are yellow in tint, as that color has the least scatter, which results in light bouncing back into your eyes.

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False. It's not that there's less scatter (other than from being slightly less light due to being filtered), it's what the human optical system does with the light.

ahtoxa11 said:

Fog lights in US are a marketing thing mainly

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Yes, they are primarily for styling and profit.

there's a problem with how manufacturers design wiring for them. If you noticed, fog lights usually cannot be used without headlights being on at the same time. Meaning, they cannot be turned on along with just the sidemarkers.

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That's not a "problem". It's deliberate, and it's correct because the overwhelming majority of fog lamps are not even close to capable of providing useful light -- not even for extremely slow speeds, regardless of the weather.

Because fog lamps are not Federally regulated in North America, their usage is left as a matter for each state (and Canadian province) to regulate. Some states/provinces say fog lamps can be used instead of headlamps if the visibility is bad enough; others say fog lamps may only be used to supplement (not replace) the low beam headlamps.

This is an issue during thick fog. In such conditions, you want your light source to be as low as possible, because that's where the fog is thinnest.

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The larger reason is because you want to maximize the distance between the light source and the driver's eyes, so as to minimize retroreflection.

Having headlights on along with foglights in low conditions doesn't do much, because you get a lot of light bouncing back to you from your headlamps.

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That depends in large part on the design of the headlamps.

So for fog lights to be effective, they need to turn out independently of main driving lamps.

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Driving lamps aren't relevant to this discussion. They are auxiliary high beams.

Additionally, they work best when they are yellow in tint, as that color has the least scatter, which results in light bouncing back into your eyes.

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That is not correct, though it is a persistent myth based on a basic misunderstanding.

They're not worth it to me, but when I purchased my 2013 Altima, I wanted the upgraded sound system & the fog lights came with the package. I'd never pay extra for them. There is one use I do have for them. In dark areas with no street lights, they illuminate the side of the road a little. I've used them on the few foggy days we have here in CA, but I didn't find them especially useful.

poiihy said:

Do they really work, or do they not?

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Overwhelmingly mostly not. See here.

The majority of fog lights are used improperly. Most people use fog lights when they are not supposed to; more than when they don't use them when they are supposed to.

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That is true. An UMTRI study found more people use fog lamps in dry weather than in bad weather!

Fog lights can actually be dangerous because they light up the foreground more, ruining your night vision with the brighter foreground and making it harder to see in the distance. And there's no use in seeing the ground closest to you because if you see something like a pothole that close, it's already too close and you can't avoid it. You need to see in the distance.

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All of this is correct.

AA#5 said:

They're not worth it to me, but when I purchased my 2013 Altima, I wanted the upgraded sound system & the fog lights came with the package. I'd never pay extra for them. There is one use I do have for them. In dark areas with no street lights, they illuminate the side of the road a little. I've used them on the few foggy days we have here in CA, but I didn't find them especially useful.

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Unfortunately you DID pat extra for them. Just not willingly. I hate when manufacturers force you into options by way of bundling. They certainly adjusted the overall cost, so we as consumers certainly pay extra for what we don't want, in this case.

-Virgil- said:

Overwhelmingly mostly not. See here.

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Yup, that's the article I read.

poiihy said:

Yup, that's the article I read.

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Then you knew the answer before starting the thread.

poiihy said:

Discuss. Debate. Rant.

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We allow discussion and debate, but ranting is unproductive. This thread now looks like an invitation for arguments now that you've revealed that you've read apposite articles.

poiihy said:

-Virgil- said:

Overwhelmingly mostly not. See here.

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Yup, that's the article I read.

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So then...why did you ask the question you asked? Seems as if you already know the answers...

Alaric Darconville said:

Then you knew the answer before starting the thread.



We allow discussion and debate, but ranting is unproductive. This thread now looks like an invitation for arguments now that you've revealed that you've read apposite articles.

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-Virgil- said:

So then...why did you ask the question you asked? Seems as if you already know the answers...

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Because I wanted to know what you people think...?
I clearly wrote "Discussion" in the title. I already have my opinion.