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Old 11th July 2006, 15:50   #31
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A small additional info, Yellow lights are for bad weather conditions, (read FOG) and Blue light are for use in Snow, as it cuts out the reflection.

Hope this helps.
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Old 11th July 2006, 17:51   #32
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Quote:
Originally Posted by sumitkalindi
A small additional info, Yellow lights are for bad weather conditions, (read FOG) and Blue light are for use in Snow, as it cuts out the reflection.

Hope this helps.
Are you sure about the snow thing? Because all the snow clearing and navigating vehicles I have seen here have yellow lights and not blue. Could you give the source of your (mis)information?

As for the physics, blue always scatters more than yellow. In foggy/sleet/rain/snow etc., conditions, blue will scatter more and actually blind the driver himself, yellow being longer wavelength will penetrate more and scatter less.
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Old 11th July 2006, 18:14   #33
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Quote:
Originally Posted by Kaizer Sozay
Hey speedsatya did the wiring and relay come as a part of the kit?
and how much did you pay for the whole thing?

yeah u get the entire wiring kit .and had ordered 2 extra bulbs and an extra relay as well..i got it for more double of what its is now as i had to pay for the duty as well ...

but i have no regrets about paying more .....as the lights rock

at present it costs about 150-160 $

http://www.autobarn.net/hemidefoglak.html

http://www.tirerack.com/accessories/hella/micro_de.jsp

http://www.autolights4less.com/hella...de-series.html
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Old 11th July 2006, 23:28   #34
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I fitted hella rectangular ones model no 450 but the angle dosent seem right will go back tommorow to set them, the beam is fantastic. dont need headlights at all now.
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Old 11th July 2006, 23:42   #35
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Quote:
Originally Posted by ram
There are ................
...........
...........

So, unless you just happen to like yellow, save your money and forget about so-called "fog-lights." They don't exist.
Thanks for that information Ram.... it sure goes against the conventional understanding of the working of fog lights that we are all used to...

cya
R
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Old 12th July 2006, 11:44   #36
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small advice from my side, during foggy days do use ur sunglassess. it may sound strange but the dark sunglassess take the contrast away to an extent making ur eyes see farther ahead. THIS IS A PERSONAL RESEARCH BASED ON PERSONAL EXPERIENCES. henceforth it will b known as NEW (Naveen in hindi) VISION.

if u dont believe me, try it & do send me ur feedback.

Last edited by naveendhyani : 12th July 2006 at 11:45.
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Old 12th July 2006, 11:58   #37
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Quote:
Originally Posted by naveendhyani

if u dont believe me, try it & do send me ur feedback.

wow ...this is something new ...so according to you ,in foggy conditions , people who have sun films on their front windscreens should be able to see better than the ones who dont have them ...
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Old 12th July 2006, 12:04   #38
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Quote:
Originally Posted by tsk1979
As for the physics, blue always scatters more than yellow. In foggy/sleet/rain/snow etc., conditions, blue will scatter more and actually blind the driver himself, yellow being longer wavelength will penetrate more and scatter less.
You have hit the nail on the head mate. Blue always scatters more than yellow, that is the reason it cuts the glare from the snow. I got this info from a offroading website long back, i don't remember the name of it though.

But beleive me, once you trest this on a snow covered landscape, you will notice the difference.

I have noticed this first hand.

Another option is to use your regular/yellow fogs, and use a light sunglass in the snow covered roads.
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Old 12th July 2006, 12:56   #39
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interesting inputs from various experiences !

i know it goes against what ram posted. at sea, in thick pea soup fog, i have observed that the yellow deck lights (sodium vapour - similar to road lights) tend to allow better penetration into the fog as compared to white light (mercury vapour) and also incandescent lights.

what say bhp-ians? noticed how it is sometimes easier to switch off the headlights and also fog lamps and just use the light of the street lights ( on fly-overs and some roads where the roads are exceptionally well lit)
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Old 12th July 2006, 13:14   #40
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Quote:
Originally Posted by speedsatya
in foggy conditions, people who have sun films on their front windscreens should be able to see better than the ones who dont have them ...
yes, my experience boils down to this. i have been personally doing this for over 7 years now.
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Old 12th July 2006, 14:59   #41
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Quote:
Originally Posted by Rehaan

Quote:
Originally Posted by ram
There are ................
...........
...........

So, unless you just happen to like yellow, save your money and forget about so-called "fog-lights." They don't exist.
Thanks for that information Ram.... it sure goes against the conventional understanding of the working of fog lights that we are all used to...

cya
R
You're right Rehaan, it does go against the "conventional" understanding of the working of fog lights that we are all used to... I used to believe in yellow lights too until I encountered lively debate among my friends.

Then I read up a lot on this. Here are two pieces to share at this time...

1.----

Some may think that yellow lights are cool(as in kewl, not lower temperature) when you're cruising!

You can't see "through" fog. You see in foggy weather by lighting up the road under the fog, illuminating as little of the fog as possible to avoid producing glare.

Reference: http://www.vclassics.com/archive/lightprn.htm

2.----

There's a lot of debate about whether yellow light is better or not in a fog-lamp.
Research says that yellow lights are no better than white lights at penetrating fog.

The theory that yellow light has a longer wavelength and is therefore less likely to be reflected by the fog particles. is complete poppycock.
Why?

Because, in physics, for "color-sensitive" backscatter to occur, the droplets of water in the liquid aerosol (aka fog) must be comparable in size to the wavelength of the colored light.

However, because the fog particles themselves are so big that they reflect all colors of light.
Basically, all light bounces off of them, so using yellow light instead of white light gives you no advantage.

Plus, in order to get yellow light, fog-light manufacturers put a yellow lens over a white light. That cuts your light output by 20 percent to 30 percent, which is counterproductive.

So if you live in a coastal area where fog is a real problem and you want to give fog lights a try, they suggest a set of high-quality, white fog lights that are professionally mounted to be sure they're aimed correctly.

Reference:http://www.cartalk.com/content/colum...bruary/08.html

Last edited by Ram : 12th July 2006 at 15:09.
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Old 12th July 2006, 15:37   #42
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Hi ram,

While I don't doubt the accuracy of your statements, it may just be a case where the human eye finds it easier to pick up the yellow light through the fog rather than a blue or white light.

The point of fog lights I think are not just to allow you to see the road ahead, but also to let the oncoming driver see you. Hence the case of "seeing through the fog" is probably not a reason for the yellow?

Just like bright orange is used for all survival gear as it is easier to spot from a distance, it may be that yellow light is easier to spot through the fog, as Capt. Pings has mentioned from his real world experience and what I have noticed as well.
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Old 12th July 2006, 18:08   #43
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Dear rtech:

The bright orange used for survival gear is reflective pigment which is optically subtractive, not emitted light which is optically additive!

To understand this, one has to come to terms with the concept of additive colors (the case of light) as opposed to subtractive colors (the case of paint).

For example, mixing all reflective pigments of the colors of the rainbow will give you black pigment as the result, whereas mixing all emissive light colors in the rainbow will give you white light as the result.

So, the argument that alternating yellow/orange and black paint stripes are used on survival gear, does not lead by implication, to the fallacious premise that orange light would be somehow be better than white light.



Yellow light is easier to spot through the fog than blue light.
If that is what you meant, you are right!
It is true that the spectral response of the human eye is higher for yellow light than for blue light.

So, if we were to use the yellow-orange photon emissions
from a 5890 Angstrom sodium-vapor lamp as a fog-lamp
then we could enjoy the advantage of lower electrical energy consumption for better visibility.

Now let's dwell a little on the "so-called" dispersive scattering effect.
Yellow light does suffers less backscatter than blue.
But this is discernible only for light scattered off the very tiny aerosol particles (dust, smoke and in hundreds of miles of fog -- blue light is scattered out of the path from the sun to the viewer of a sunset, leaving white-minus-blue light to reach us... so we sees a yellow, then orange, then red sunset.

Mind you, it takes sunlight penetrating through miles and miles of fog, to get this color effect!

The size of water drops in fog on the road is not small enough for producing the kind of color scattering mentioned above. If it did, then in a fog, white headlights would appear very red to oncoming traffic. We know of course, that they don’t, don’t we?



We must appreciate that, filtration of light is an intensity-destructive process, not an intensity-enhancing process!
So it does not follow that yellow or amber light is any easier to spot through the fog than the unfiltered white light that yielded that yellow component, after filtration! If you wanted to be seen better, a flashing aircraft strobe (such as used on airport emergency vehicles) would be more effective, but we don't see much of those as car fog lights.

Conventional automotive yellow fog-lights produce full-spectrum white light via an incandescent filament or halogen source. Then they filter off the blue end of the spectrum, leaving yellow light behind.
This trashes both:
the visibility objective
as well as
the efficiency objective.

Filtering off and discarding the blue component, does not make the resulting light any brighter. If anything it will make it dimmer!

It would be more visible to just leave the white light unfiltered.
The oncoming driver would see you better if you used all the white light.
Accordingly, modern European cars no longer have amber fog lights!

Most likely, the real reason that people have used yellow fog lamps is for their cool, bold, aggressive image.

Last edited by Ram : 12th July 2006 at 18:14.
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Old 12th July 2006, 18:24   #44
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Whoa Thanks Ram I am sure most of us didnt knew this & after reading it surely makes lot of sense

Man we can a learn a lot from your experiences.
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Old 12th July 2006, 22:57   #45
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Dear All I have cut the bottom part of my zen grill and fitted hella 450 foglamps on them the lights are bolted near the number plate.
The problem i currently face is in focussing the beams the lights keep shaking while i drive & i have to adjust them everytime i stop.
Any suggestions please .
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