# Driving lights, fog lights? Any experience/opinions?



## cobb (May 7, 2006)

I was reading in the drivers manual about how not to use your high beams on fog and how lighting needs to be low to the ground to illuminate the road not the fog and that possible benefit of fog lamps. 

I have a kit, infact two from the experience when I added lights to my wheelchair a few years that I could easily install to the van. Infact, Ive found a few spare bulbs and the stock wiring kit with lighted switch.

Since the vans lights are at elbows height, I think I can see where having lower lighting can help. 

I have the kits from the nightblaster series of cheap kits from walmart. Its a little oval shape lamp just large enough to house an h3 lamp that has a yellow tint lense and projects a wide flat beam. 

A friend of mines use to get piaa lamps for his cars and trucks, but thats a good 200-400 bucks I am not looking at spending. My dad had a pair of the generic fog lamps from the parts counter at the local vw dealer when he still had his rabbit. Basically a rectangle sealed beam on a mount. 

Thanks


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## ACMarina (May 7, 2006)

I've found that using my high beams alone leaves a rather dull spot in a close-range area. In a perfect driving world, you wouldn't have to worry because if it wasn't there at 100 yards, it still wouldn't be there by the time you got there. But since it's not a perfect world, a small animal or something could easily wander out into the road in the shadow of my lights. Personally, I run my fog lights (or driving lights) any time my lights are on, and while Ford doesn't approve I run them with my high beams too..


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## Diesel_Bomber (May 7, 2006)

You're a flashaholic. Do you REALLY want the 2D-plastic-Rayovac-with-dead-batteries of the auto lighting world on your van? Most Walmart or Autozone cheap fog lights are crap. They'll allow too much light upward to reflect off the fog and back into your eyes, making it so you'll see better without the "fog" lights. This is exactly why using your brights in fog is a bad idea. The key is a very sharp, knife edge cut off. Bright below, dark above. Most cheap lights have some sort of color coating on them which emits a large amount of blue or purple light in addition to yellow. Yellow does debateable good, but blue or purple should be avoided. They're also cheaply made. The reflective material comes off, water gets inside, and the light is useless in a few months. Good Hellas or Cibies will last like a Surefire. I've had very good service from Hella Micro DE fog lights. Good luck!


Cheers. :buddies:

P.S. Proper wiring is incredibly important too. Relays and 10awg wires directly from the battery or alternator positive post. Don't forget to make the ground wire just as big as the positive wire, and don't go to a convenient ground point on the bumper or fender or whatever. Go straight back to the battery negative terminal or the alternator case. Same thing with your headlights, you'll notice a hell of a difference.


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## Orbit (May 7, 2006)

yes lots of experience, i have posted this a few times now. but it has fallen off the planet, so to speak. So here is the theory, and reality. i'll leave the rest to you. if you'd like to know more, PM me.

Question: Why are fog lights yellow? Does it help that they are? Does it matter if you are driving in city or countryside? 


Answer: My understanding is that it is important for fog lights to be one color 
(rather than white, which is all colors) because the different 
wavelengths(colors) of visible light scatter off the fog droplets 
differently. This phenomenon is known as "dispersion," because the 
different colors of light in an image will separate from each other, 
causing the image to "disperse." If you illuminate the road with only one 
wavelength (color) of light, the images of the objects you see will still 
become somewhat blurry because of the scattering of light by the fog, but 
at least you won't have extra problems from dispersion. So, if we want to 
use just one wavelength of light, which wavelength should we use? It turns 
out that light with short wavelengths scatters more than light with long 
wavelengths (short to long: violet, indigo, blue, green, yellow, orange, 
red). So, a long wavelength light will be best. There's another thing to 
consider, too: our eyes are not equally sensitive to all colors. It turns 
out that we are most sensitive to yellow and green light. So, our best 
compromise between sensitivity for our eyes and a long wavelength for least 
scattering is yellow light. 
A consideration used in street lighting is cost and efficiency. You 
may have seen some yellow street lighting in some places; this is 
"low-pressure sodium vapor" lighting. The special thing about this light 
is that it is almost entirely one (actually two very close together) 
wavelength of yellow light, and that it gives the most illumination for the 
amount of electricity. A big problem with this light, though, is that it 
throws off color perception. Under sodium vapor light, something blue 
looks gray. This makes it hard to, say, recognize your car in a parking 
lot. 

There was teh theory, now here is the reality. 

There is no good reason why fog lights are yellow 

"First I'll give you the wrong explanation, which you can find here and 
there. It goes something like this. As everyone knows, scattering (by 
anything!) is always greater at the shortwavelength end of the visible 
spectrum than at the longwavelength end. Lord Rayleigh showed this, didn't 
he? Thus to obtain the greatest penentration of light through fog, you 
should use the longest wavelength possible. Red is obviously unsuitable 
because it is used for stop lights. So you compromise and use yellow 
instead. 


This explanation is flawed for more than one reason. Fog droplets are, on 
average, smaller than cloud droplets, but they still are huge compared with 
the wavelengths of visible light. Thus scattering of such light by fog is 
essentially wavelength independent. Unfortunately, many people learn 
(without caveats) Rayleigh's scattering law and then assume that it applies 
to everything. They did not learn that this law is limited to scatterers 
small compared with the wavelength and at wavelengths far from strong 
absorption. 


The second flaw is that in order to get yellow light in the first place you 
need a filter. Note that yellow fog lights were in use when the only 
available headlights were incandescent lamps. If you place a filter over a 
white headlight, you get less transmitted light, and there goes your 
increased penetration down the drain. 


There are two possible explanations for yellow fog lights. One is that the 
first designers of such lights were mislead because they did not understand 
the limitations of Rayleigh's scattering law and did not know the size 
distribution of fog droplets. The other explanation is that someone deemed 
it desirable to make fog lights yellow as a way of signalling to other 
drivers that visibility is poor and thus caution is in order. 


Designers of headlights have known for a long time that there is no magic 
color that gives great penetration. I have an article from the Journal of 
Scientific Instruments published in October 1938 (Vol. XV, pp. 317-322). 
The article is by J. H. Nelson and is entitled "Optics of headlights". The 
penultimate section in this paper is on "fog lamps". Nelson notes that 
"there is almost complete agreement among designers of fog lamps, and this 
agreement is in most cases extended to the colour of the light to be used. 
Although there are still many lamps on the road using yellow light, it 
seems to be becoming recognized that there is no filter, which, when placed 
in front of a lamp, will improve the penetration power of that lamp." 


This was written 61 years ago. Its author uses a few words ("seem", 
"becoming recognized") indicating that perhaps at one time lamp designers 
thought that yellow lights had greater penetrating power. And it may be 
that because of this the first fog lamps were yellow. Once the practice of 
making such lamps yellow began it just continued because of custom." 


Also, take a look at the following web site: 
http://www.gi.alaska.edu/ScienceForum/ASF5/593.html


there are a few other opinions on this now, relating to the human eye and contrast, differentiation between colours in a closed environment(ie inside fog) etc etc. but This should get you started. as i said PM me if you want more details.

ORB


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## cobb (May 7, 2006)

Yeah, looks like when I raise the aim of the stock lamps a dark spot will develop in front center of the van. I hadnt plan on filling that gap, but did want some lowered mounted lamps to see better through fog. 

They make 2D-plastic-Rayovac-with-dead-batteries I could zip tie to the front bumper!?!?!? Just kidding, Id wire two p61 lamps in series and zip tie them to the bumper. 150 bucks for good aftermarket lights? Whats the diff for HID ones?

Yeah, looks like a mixed bag on rather or not they will be useful. Seems my fathers side of the family ends up with cars with poor lighting that is about worthless at night, where as my mothers side they seem to be more than adquate for legal safe speeds.


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## Diesel_Bomber (May 8, 2006)

Orbit- I agree completely with your findings. If you should discuss anything further, would you please do it in the open on the forum, or include me in the PM's? I'd really like to read along.

Cobb- The "dark spot" you speak of is due to the horrible US spec beam pattern you have. A quick check shows that '94 Econolines don't have sealed beams(that's the correct year, right?) so that'll be hard to fix. Sealed beam replacement lights with European-spec(otherwise known as E-code) beam are readily available, but yours will take some engineering. I Googled for a good description of the difference between US spec and Euro spec headlights, but couldn't find anything. I'll look more but I don't have any more time right now. Here's the HID version of the Hella Micro DE, if that's what you meant.


Cheers. :buddies:


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## Orbit (May 8, 2006)

No worries DB. i posted the bit about PM's when the thread was in the cafe section....as i wasn't sure if it was destined to be locked or moved. since it was moved, i'm happy to discuss it further. But i don't want to Hijack this fellas thread.


On another note.
You have a perplexing request .... i'm not sure what you exactly want from your lights cobb. Could you elaborate? Maybe i can find a soultion.

Are you after lighting to use in fog?
If so do you want to see better in fog? 
Or do you want to be seen?
are we talking fog during daytime?
Or during the night?
On straight or winding roads?
Hills or flat?
And at what altitude? (sea level or above say 2000m)

before you decide to do anything yo uneed to have atleast thoses questions answered.

ORB.


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## spock (May 8, 2006)

use to have a 1970 bmw 2002 with cibie headlights. these 7" round replacements had a 100w quartz bulb. also had 2 cibie fog lights(separate sw) plus 2 kinby driving lights(pencil beam). 510 watts total was sufficient on a clear night, but a big strain on the alternator. for fog you need a lens that is vertically fluted giving a wide dispersed beam. the color of the beam can be white or yellow, it doesn't make a difference for your vision. if you are coming towards me, i might spot your car thru the fog sooner if the beam is yellow. more on that later. my cibie fog lights were 6"h by 8"w with fluted clear lens. if you stand in front of your car, they should have severe cutoff about 2.5 feet above ground with a wide beam like a large piece of pie. you see better not because of distance, but because of your perpheral vision giving you more visual inputs. worked for army corp of eng. on miss. river in louisiana. all barges and boats have yellow running lights at night. this evolved from tests ran back in 1920 that showed that the light that can be seen best; the longest distance thru fog by a person is a "flickering" kerosene lantern flame(yellow). from this evolved yellow boat lights and yellow fog lights. many tied off barges today still use kerosene lanterns at night.


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## cobb (May 8, 2006)

Its a 96, they look liie sealed square ones to me.

The idea was to mount them because I have them. Ive seen them on cars from time to time and was wondering how good were they or just a gizmo. THe vans lights seem fine for day or night dirving without fog, just need to raise them a hair. During midmorning you can get fog so thick you cant see several feet in front of you and I thought that would be what I wanted to fix. Also fog in general, I would mount these low as possible since the head lights are mounted high.


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## zespectre (May 8, 2006)

Since I'm so famous for "real world" examples of stuff... <grin>.
I have found over the years that yellow fog lights do seem to make a bit more of a difference -for me- YMMV. Not because they penetrate better but because when they reflect off of something moving (like a deer) I tend to notice a moving blob that is yellow a bit more quickly.

Now in theory aux lights are supposed to work like this...
Fog lights should come on with low beams and provide a wide flat beam that hits low and is reflected high. This effect tends to penetrate fog better without just reflecting off the fog and blinding you.

Driving lights should come on with the high beams and are intended to fill in the low and closer gap that gets left when your lights switch up. {EDIT, this is incorrect and should read... Driving lights should come on with the high beams and are intended to suppliment the high beams.}

Of course Virginia DMV has it TOTALLY f&%ked up and their regulation is that driving lights come on with the low beams and fog lamps are supposed to come on with the high beams?!? Who runs fog with high beams on???

Another trick we used to use (out in the rural areas) was to aim the passenger side fog light just a little bit off to the right. Really worked great for spotting deer off to the side of the road BEFORE they ran out in front of you.


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## Diesel_Bomber (May 9, 2006)

Orbit- Thanks.

Cobb- '96, excuse me. Is your entire headlight replaceable; bulb, reflector, and lens together? Or just the bulb? If it is the bulb, reflector, and all, check out this website for some absolutely AWESOME headlights. If you're used to stock US sealed beam garbage, you're in for as big a surprise as going from Mag to Surefire. No lithium batteries needed. :thumbsup:

Zespectre- Actually, "driving" (a very general term) lights are generally for shining farther than your high beams. Filling in the dark area just in front of your vehicle is a bad idea. The extra light will cause your pupils to contract, reducing your night vision and your ability to see in the distance, where you need to.

Cheers. :buddies:


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## Orbit (May 9, 2006)

well I would hold your shots a bit, big D.
while i agree with you, in principle.... In fog (this is the key point to Z's post)
he has found that he sees better with the aid of some yellow light (changing the contrast of the environment) a sound idea, noting that in fog, you visiblity is markedly reduced so your long range vision, ie 100m plus, is of little consequence, further whilst in fog during the day there is a rather significant amount of glare/scattered light which doesn't help you distingush the environment(next time your in fog during the day do as i do and wear polarised glasses you'll see what i'm talking about).
during the day your yellow lights are more of a warning to others that you are approaching, of course there are any number of variables that can stop that being the case.
During the night however, throwing a ginormous amount of light ie driving lights into the fog will most probably successfully cause you to select low beam rather quickley, as alot of the light is reflected/scattered/bent/uselessified back at you.
However, if you have low mounted flat beampattern (or tight spot) lights the amount of back scatter is greatly reduced, adding colour to the beam will change the contrast in the environment to a degree and allow you to see better....there is a limit to the amount of light you want though, ie having 100watt driving lights down low will still cause significant back scatter. dropping that to 50watt(max i would consider useable as fog lights) will give minimal back scatter ie max pupil size....leading to more defnition of the environment etc etc.

ORB.
i've got more to say but i'm off to eat.


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## Diesel_Bomber (May 9, 2006)

Yep Orbit, again I agree with you completely. But you should hold your shots, too.  In my post about driving lights I ASSumed that Zespectre meant in clear weather, and that use is what my comments were directed towards. It didn't even come to mind that anyone would consider using driving lights in fog. You certainly don't have to explain why that's a bad idea.


Cheers! :buddies:


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## zespectre (May 9, 2006)

Diesel_Bomber said:


> Yep Orbit, again I agree with you completely. But you should hold your shots, too.
> 
> 
> 
> ...


 
To clarify for everyone, I was strictly talking about fog driving and why (in terms of operating in fog) the VDT regulations are not only backwards, but in my opinion they are dangerous because if you follow the regs you can either have...

High beams and fog lamps (in which case the high beams will usually create a blinding reflection back at you)
or
Low Beams and Driving Lamps (in which case, by acting as aux high beams, the driving lamps may create the same no-visibility situation)

Diesel Bomber is completely correct that "Driving Lights" are supposed to act as a suppliment to your high beams. I mistyped earlier (mixed some fog lamp text up with the driving light description) and have made a correction.  

Via PIAA lighting... http://www.piaa.com/Lamps/LightAimingGuide.html


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## Orbit (May 10, 2006)

AH! so we are all in agreement lol.

OH well, it was worth a bit of a rant, lol.
I was a little worried about having to explain using highoutput in fog, but you never know.

Z.....lets just say i'm glad i don't live in those states, those regs are quite odd!!

perhaps this is a lessong to everyone to hit the preview button before posting....and read others posts proberly lol.
That PIAA site is a good guide, though a optimium beam pattern is entirely dependand on any number of variables.


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## Diesel_Bomber (May 10, 2006)

Orbit- Indeed, I'm glad we agree.

Zespectre- My apologies for mis-reading you. I bash my head on the ground at your feet. 

Maybe next time we can discuss the best color for Luxeon V based DRL's. :touche:


Cheers! :buddies:


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## Ken_McE (May 10, 2006)

Cobb, do you have a pic of the front of the van I could look at? I might be able to help. I don't know much about raleigh scattering, but I had my last car modded up from two headlights to six, and they worked OK, so I know all about the best kind of zip ties to use and that kind of practical stuff.


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## zespectre (May 11, 2006)

Diesel_Bomber said:


> Orbit- Indeed, I'm glad we agree.
> 
> Zespectre- My apologies for mis-reading you. I bash my head on the ground at your feet.
> 
> Cheers! :buddies:


 
He he he, I don't think thats necessary.
It's really easy to mis-read/misunderstand what others are writing, especially if you are prone (like me) to reading stuff at 11:30pm when you really should be in bed!


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## cobb (May 11, 2006)

Its just the basic econoline van, I believe the front face is unchanged the past 10 years. It has just two lamps and two markers/turn signals and some openings for cooling.


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## nocte-diem (Jun 7, 2016)

Just a few comments on fog lights:

Fog lights are ideally located as low as possible to the ground. That way the beam of light passes under the layer of fog which usually hovers bit above ground. Many cars, including VW and Audi models, contain fog lights that are integrated into the headlamp assembly. Since these fog lights are really too high to be effective as fog lights, they are more useful as supplemental driving lights in conjunction with the low beams, or as curve lights. Some recent cars, including the Jeep Renegade, actually use their fog lights as curve lights. The fog light on one side will come on if the blinker is set or if the car gas the steering wheel turned beyond a certain point. That is very useful and a simplified implementation of smart lighting.

As for yellow fog lights, I am not sure where they are legal and where not. Yellow light causes less glare than more white (which is still yellow, in case of halogen light sources) light and thus may be preferable in foggy conditions. Personal preference may also be a factor.

Nobody mentioned rear fog lights and I would like to add the answer to a question I keep hearing. People ask me why their car has only one fog light. It's so that the fog light is not mistaken for brake lights. Although, two foglight are legal in some jurisdictions. For example, in much of Europe, one or two rear foglighst are legal, but most car makers fit their cars with only one rear fog light.


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## sunwestpainting (Jun 24, 2016)

You have to read in the drivers manual about to use your high beams on fog and how lighting needs to be low to the ground .


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## Subterrestrial (Jul 28, 2016)

I don't know if anyone else has this problem, but if it's raining heavily at night and there's a lot of water on the road I can't see the lines, markings, etc on the road surface. My fog lights light up the road nicely. 

They help with snow as well. I find that even if it's not snowing heavily, the falling snow flakes are distracting and the fog lights help me focus better on the road.

So that's my take on fog lights; essential as they're not just for driving in fog.


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## spurshooter (Jan 2, 2017)

OK....a 10 year old thread with a few new posts...I'll play. 

My experience with fog lights is that they should be very well controlled beams. The better the cutoff and less the "artifacts" and spill/bloom from the beams, the better. I have some Rigid Industries DOT fog lights on my pickup that have extremely well controlled beams with very little spill. They are incredible lights, although only about 1600 lumems. Beam control is every bit as important as the output.








I also have these Baja Designs SII wide beam 2200 lumen lights that are very well controlled, but with not as sharp a cutoff as the Rigids. The clear lens set to the right are long range spots. 





Of course, with modern HID shutter controlled high beams with super sharp cutoffs, the need for fog lights is reduced.


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