ATTN: Daniel Stern... Question...

On Mon, 10 Jan 2005, C.H. wrote:

> The original reasoning was, that the fog usually is less dense closest
> to the ground and thus the fog lights, which usually are mounted
> significantly below the headlights, were supposed to illuminate the road
> better that way.

That is not correct.

-DS

On Tue, 11 Jan 2005, Jan Kalin wrote:

> The main reason for foglights placement is the angular dependence of
> intensity of scattered light.

This is mostly true as far as it goes, but it's not quite correct as
written. That's because fog lamps are found at a wide range of mounting
heights, from "6 inches off the road surface" all the way up to headlamp
axis height. Your statement would be more accurate if it said "A major
reason *why fog lamps work best when placed low relative to the driver's
eye height* is the angular dependence of intensity of scattered light.

> by lowering the foglamps as much as possible you minimise the intensity
> of the (useless, blinding) backscattered light.

Yes. You also maximize the beam reach, because high-mounted fog lamps must
be aimed very low to compensate for the high mounting height in terms of
glare and backdazzle. Low-mounted fog lamps can be aimed with less
declination and still give acceptably low glare and backdazzle.

> I had the chance to try out foglamps in a relatively dense fog and there
> was no question that the road was more visible than without them.
> Obviously the foglamps need to be well made.

That last sentence is the critical key point. The vast majority of "fog
lights" on the road in North America are worthless *at best*.

DS

On Tue, 11 Jan 2005, Jan Kalin wrote:

> The main reason for foglights placement is the angular dependence of
> intensity of scattered light.

This is mostly true as far as it goes, but it's not quite correct as
written. That's because fog lamps are found at a wide range of mounting
heights, from "6 inches off the road surface" all the way up to headlamp
axis height. Your statement would be more accurate if it said "A major
reason *why fog lamps work best when placed low relative to the driver's
eye height* is the angular dependence of intensity of scattered light.

> by lowering the foglamps as much as possible you minimise the intensity
> of the (useless, blinding) backscattered light.

Yes. You also maximize the beam reach, because high-mounted fog lamps must
be aimed very low to compensate for the high mounting height in terms of
glare and backdazzle. Low-mounted fog lamps can be aimed with less
declination and still give acceptably low glare and backdazzle.

> I had the chance to try out foglamps in a relatively dense fog and there
> was no question that the road was more visible than without them.
> Obviously the foglamps need to be well made.

That last sentence is the critical key point. The vast majority of "fog
lights" on the road in North America are worthless *at best*.

DS

Daniel J. Stern wrote:
> On Mon, 10 Jan 2005, Cory Dunkle wrote:
>
> > What is the purpose/intention of fog lights. In other words,
> > why were they created and what purpose do they serve? When are
> > they to be used if your vehicle is so equipped? Thanks.
>
> See
>
http://www.danielsternlighting.com/t...fog_lamps.html
>
> It answers all your questions and more.

While we're on this topic, I saw something new to me the other day:
the lower half of the headlight glass on this car was tinted
yellow and pink. From side-on it was almost invisible, but if
the car was in the distance behind you, then the headlights
looked like very bright reflective highlighter colours.
This was all in the daytime so I have no idea what it would do
at night.
What would be the purpose of that tinting ? Showing off, or
some sort of visibility aid?

Daniel J. Stern wrote:
> On Mon, 10 Jan 2005, Cory Dunkle wrote:
>
> > What is the purpose/intention of fog lights. In other words,
> > why were they created and what purpose do they serve? When are
> > they to be used if your vehicle is so equipped? Thanks.
>
> See
>
http://www.danielsternlighting.com/t...fog_lamps.html
>
> It answers all your questions and more.

While we're on this topic, I saw something new to me the other day:
the lower half of the headlight glass on this car was tinted
yellow and pink. From side-on it was almost invisible, but if
the car was in the distance behind you, then the headlights
looked like very bright reflective highlighter colours.
This was all in the daytime so I have no idea what it would do
at night.
What would be the purpose of that tinting ? Showing off, or
some sort of visibility aid?

On Wed, 12 Jan 2005, Old Wolf wrote:

> While we're on this topic, I saw something new to me the other day: the
> lower half of the headlight glass on this car was tinted yellow and
> pink. From side-on it was almost invisible, but if the car was in the
> distance behind you, then the headlights looked like very bright
> reflective highlighter colours. This was all in the daytime so I have no
> idea what it would do at night. What would be the purpose of that
> tinting ? Showing off, or some sort of visibility aid?

Yet another stupid aftermarket mod by some dumb kid.

On Wed, 12 Jan 2005, Old Wolf wrote:

> While we're on this topic, I saw something new to me the other day: the
> lower half of the headlight glass on this car was tinted yellow and
> pink. From side-on it was almost invisible, but if the car was in the
> distance behind you, then the headlights looked like very bright
> reflective highlighter colours. This was all in the daytime so I have no
> idea what it would do at night. What would be the purpose of that
> tinting ? Showing off, or some sort of visibility aid?

Yet another stupid aftermarket mod by some dumb kid.

"Daniel J. Stern" wrote:
>
> On Mon, 10 Jan 2005, Cory Dunkle wrote:
>
> > What is the purpose/intention of fog lights. In other words, why were
> > they created and what purpose do they serve? When are they to be used if
> > your vehicle is so equipped? Thanks.
>
> See
> http://www.danielsternlighting.com/t...fog_lamps.html
>
> It answers all your questions and more.
>
> DS

I wish the informationj from your reference was printed on a
label placed next to (or over) the fog light switch on all
vehicles. I hate fog lights - or at least fog lights as used
by many Americans.

Ed

"Daniel J. Stern" wrote:
>
> On Mon, 10 Jan 2005, Cory Dunkle wrote:
>
> > What is the purpose/intention of fog lights. In other words, why were
> > they created and what purpose do they serve? When are they to be used if
> > your vehicle is so equipped? Thanks.
>
> See
> http://www.danielsternlighting.com/t...fog_lamps.html
>
> It answers all your questions and more.
>
> DS

I wish the informationj from your reference was printed on a
label placed next to (or over) the fog light switch on all
vehicles. I hate fog lights - or at least fog lights as used
by many Americans.

Ed

On Thu, 13 Jan 2005, C. E. White wrote:

> > http://www.danielsternlighting.com/t...fog_lamps.html

> I wish the informationj from your reference was printed on a label
> placed next to (or over) the fog light switch on all vehicles.

Better: A quickie IQ test that the driver must pass before the fog lamps
will energize.

For that matter, a quickie IQ test that the driver must pass before the
ignition will energize.