What is the best LED light for fog?

The other night I was outside in the fog playing with my flashlights. /ubbthreads/images/graemlins/grin.gif I realized that I don't have a good LED light that will throw in fog. My MR-X was WAY to bright, and the spill light blinded me when it was reflected by the fog. The SBP had too wide of a beam, and would only throw about 40 feet. My MR-X only worked to about 50 feet (it can usually to 200-300 feet no problem). So what LED light is best for throw when it is foggy? How does the McLux PR work? Will a LuxIII in a M@g reflector work? /ubbthreads/images/graemlins/help.gif

Only saw the first part of your topic "What is the best LED light" and the first thing that pops into my head was "the next one".

However I think this is a very good topic and will start by contributing what little I know (or think I know).

The main problem in fog is back scatter, that is the light thrown back at the observer. Fog lights on cars combat this in two ways. The first is color. Fog like other moisture in the air reflects the blue end of the spectrum better. "Why is the sky blue?" So by using a color to which our vision still responds well, amber (yellow), that problem is reduced. Second the light tends to be reflected more directly back so that changing the angle of the source of the light should improve the matter. This is why car fog lamps are mounted low though a high mount might work as well. In theory I think the best would be a light mounted above what you want to see aimed 90° from your line of sight and with the source shielded from your view. Not really feasible with a flashlight. I have never seen these issues addressed in a flashlight but amber L.E.D.s are available. A third issue, as you have found out, is brightness. A balance between having enough light to see as far as we need but not so much as to "swamp" our vision with the back scatter.

There may be fog conditions so heavy that nothing short of assisted night vision would help!

There was a discussion on this board a while ago that one of the reasons to have a Maxabeam was its very narrow spot--and that it worked well in fog.

I don't know, but I'm waiting for a foggy situation to try out my KT-4 or my SRTH Turbohead with an N2 lamp. It's got the least sidespill of anything I have.

I guess a black felt-lined snoot would cut it even more.

I don't think I have a fog-friendly LED. I don't even think the custom LED lamp for the KT-4 would be as narrow as the N2 or have as little side spill as the N2.

Cheers,

Richard

ummmm, would it be an Amber led????

The only reason I say this is arn't foglights amber???

An LED light with a tight beam is the only thing that will get through fog. Any sort of sidespill will just be reflected back. Supposedly light towards the warmer colors cut fog better than those on the sunlight/blue side. Not positive about that tho.

sounds lke an amber X1 would be just the thing.

I believe the concept of amber for fog has been debunked. Narrow beam is the key.

The original idea of an amber light was born from the concept that different wavelengths have different angles of refraction. So amber was chosen because it was towards the lower end of the spectrum and was thus thought to have better refraction characteristics. In the end, the difference in angle of refraction across the visible spectrum is pretty small, so color doesn't matter much.

Has anyone tried a McLux PR w/ 1 watt LS or luxIII in the fog? How about a LuxIII in a M@g reflector? I want a light that is bright enough to throw at least 100 feet in the fog without blinding me because of a large hotspot or very intense spill light.

i don't think there is a light that'll throw 100 feet in the fog..
@ least not very thick fog..

Edit:
outside of mods or HID's..

[ QUOTE ]
RonM said:
I believe the concept of amber for fog has been debunked. Narrow beam is the key.

...

[/ QUOTE ]

OK, I was afraid someone would make me do actual research. Though I though the main reason for a green laser (a narrow beam also) was that more of the light would be reflected back by the moisture in the air. Or may its just because our eyes are more sensitive to green than red.

Anyway, main answer found so far "Actually, the jury is still out on the effectiveness of fog lights" from NASA.

I'm continuing the hunt.

GWB, dig a little deeper in the link you provided and you'd get to the Cartalk Columns which have this to say about amber fog lights:

"Tom: So the question becomes, to yellow or not to yellow? There's a lot of debate about this, but the research says that yellow lights are no better than white lights at penetrating fog. The theory bandied about was that yellow light has a longer wavelength and is therefore less likely to be reflected by the fog particles. Turns out, this is complete poppycock.

Ray: Apparently, 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.

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

Here's the link.

I read that and Click and Clack have been wrong before! In this case it appears they are not. Found the answer in that fog particles are slightly larger than those in clouds.

How is this the answer? Clouds reflect white! All colors! If the particles were smaller then amber might pass but I guess after thinking about it fog reflects white.

The only real answer is infra-red. Night vision equipment. Next time its real foggy here I'm breaking out my Gen I and maybe even my old Gen "0" to try it.

BTW, I never disagreed with the side spill issue.

Here's a link to the "Foggy night" thread

THE FLASHLIGHT BEAM ON A FOGGY NIGHT

Brightnorm

Any of you who have seen the green flash know that various wavelengths of light do refract at different angles, right? I think? So maybe there is someting to a certain band that will "pass" through the moisture particles at greater angles than others? I think the big problem though is the backscatter and the best way to avoid this is to have the light source as far removed from your line of sight as possible. Having the fog lights lower on a car makes sense to this dummy. For a handheld light, me thinks a focused beam only, of tight beam angle with no flood is the best shot. I think a 4' tall stalk mounted on top of a hard hat would be just the ticket provided one removed their hat prior to going inside.

Actually the best LED light for fog is the one your friend is using when he (she) is up real close to the target and off axis from your line of sight.

OK, I'll move on.............

Having run many trail races at night, including some in pea soup fog, I concur with Don and others, that the only way to cut through the fog (no pun intended) is to get that light as low to the ground as possible (note to self: lights on ankles??).

Wearing a headlamp in fog is totally useless, unless you want to blind yourself.

So, yes, a tight beam and low to the ground works the best, the color of the light being pretty much meaningless, in my opinion.

maybe someone would be interested in this light that Craig reviewed @ the Led Museum. /ubbthreads/images/graemlins/grinser2.gif

The LED Belt Light

OK, now that we eliminated color as an issue in fog I would like to bring it up again for a different reason. Now using an amber, or any other color, filter is going to cut the brightness. But in generating light with an LED with current designs monochromes are going to be much brighter. And with human vision blue-green (cyan) and amber have certain advantages. The main question then becomes is the loss of the ability to distinguish colors worth the increased brightness?

An amber HD in a mag relfector... Would be a tight beam and dark in color. Or a warm-white luxeon... but not sure how LD's do in mag relfectors...

[ QUOTE ]
gwbaltzell said:
OK, now that we eliminated color as an issue in fog

[/ QUOTE ]

Not so fast....No, not really - the concensus has only shown that amber/yellow might not cut through fog any better than any other color -

BUT has anyone brought up that amber/yellow gives better perceived contrast? the color (perhaps for some people) also seems to be less dazzling. Also for a car there is another function - that is to be more visible to oncoming cars.....

Sometimes things in common usage may be there for a good reason -
I know it's always nice/hip to be able to "debunk myths" - but the use of amber/yellow fog-lights has been around for so long and its usage is so common - there may be a very good reason for the use of amber/yellow - even if all of us combined can't explain it, and one "hip" web site seems to want to debunk it........

The two main functions of amber/yellow car fog-light filters are to cut off the top beam to limit reflection back to the driver - but why yellow/amber? especially since it cuts the light by 20-30% - seemingly defeating its purpose - when anyone including one's cousin could have easily made a clear focussing lens to do just the light beam shaping/cutting - yet people persist in using amber/yellow - surely it should be easily demonstrable that the clear lens would be superior to the amber/yellow filter (since amber would be 20-30% less bright)? - were people that dumb? Somehow I don't think so...... I think amber/yellow does make a difference - on cars.

This however does not necessarily translate directly to handheld flashlights......

Oops, what I meant to say was we eliminated color as an issue in reducing back scatter! The point I was trying for and missed was might there be other advantages.