Fog (flash) Lights?

Walking tonight, I realized that my Fenix P2D was OK, and my Surefire E1L was better... but still lots of glow coming back at me.

Fog caused visibility to about 30 yards.

So, either 1) is there a good filter for either of these (I have a red one for the E1L), or 2) is there a good flashlight for foggy weather?

i think usually incan is better for fog

Shreknow91 said:

i think usually incan is better for fog

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Beam pattern is more important than color. A throwier light with little spill will penetrate fog better than a floody light.

There's not really much of a solution here. If you think about it, fog is made up of little droplets of water. So what you're really asking is for a flashlight that can penetrate droplets of water. The more light you shoot out, the more light you're going to get back in your face. As LukeA mentioned, beam pattern is more important than color. The reason is that if you have a throwy tight spot beam, the reflected light will be a small point. Furthermore, if you hold your spot light away from your line of sight, then you will see more of the illuminated object rather than the reflected light. This is why car's fog beams are down low. The light is not only shining under the fog, but is also at a farther distance from your line of sight.

Supposedly bluer lights are composed of a wavelength that is more susceptible to being refracted which scatters the light. This is why they used to (some still do) promote yellow foglights. The yellow beam's wavelengths are suppose to scatter less. This could be true theoretically, but in practice, no one can say for certain.

It IS noticeable that bluer lights don't illuminate objects well through fog for a different reason. LED's cast a beam that lacks the redder part of the light spectrum, while incandescents are more balanced so to speak. So when your led light hits an object, you seeing more of one color than the others, primarily blue. Whereas when you use incandescent, an illuminated object reflects back a lot more color. This comes into play when you add fog to the equation. The blue light reflecting against the white fog makes it hard to see make things out. Incandescent light on the other hand reflects back more colors such as the yellow to red colors. The warmer colors contrast better against the white fog in my opinion.

As mentioned before, it's more important though that the beam be narrow so that the fog that is illuminated is not in your visual path, and that you hold the beam as far from your line of sight as possible. If looking down, the light should be above your head, and if looking up, the light should be below (garden hose grip). Pretty much intuitive when you're actually in dense fog with a light.

Tiablo A9 anyone? :devil:

Crenshaw

Although the A9 is a super thrower, it is still an reflectored LED light. LED's emit a lot more light as spill than an incandescent. It would be even better to use a narrow beam optic.

Aspherical anyone? =P

true dat...asphearical anyone?...:thumbsup:

Crenshaw

Next time it's good and foggy I'll have to try my SF L1 and E1B since they have a pretty tight beam, and not a lot of spill, and compare with with some other throwers that have reflectors and more spill. Say a SF L1 vs a Dereelight DBS.

Mdinana said:

Walking tonight, I realized that my Fenix P2D was OK, and my Surefire E1L was better... but still lots of glow coming back at me.

Click to expand...

I believe the E1L uses an optic isntead of a reflector. If so, that is the reason why it performed better than your P2D -- optics generally have much less spill. With the P2D, a big fraction of the light is spill -- this spill light does not reach your intended target, yet still creates a lot of backscatter. This makes the contrast ratio between light hitting the target, and light reflecting off the fog, much worse.

Incans generally do better for three reasons, in order of increasing significance:

1) Longer wavelength light is less prone to scattering.
I find this effect is minor. Also, outdoors there aren't a lot of things that refelct blue light. Dirt and trees etc, reflect red and green.

2) Very few things in nature reflect blue light.
This means if you were to light tree with an equal number of incan lumens, or LED lumens, the tree lit with the incan will reflect more back. However, the light reflected back by fog will be roughly the same in both cases, meaning the LED will have a worse contrast ratio between how bright the target appears, and how bright the fog is

3) Incans filament emit light in a 360 degree angle, LEDs emit light their light "forward" in a 150 degree angle.
This means the same reflector might capture 80% of the light from an incan, but only 30% from an LED. The non captured light exits as spill, and spill is BAD in fog.


That said, I don't believe LEDs are inherently bad for fog. A purpose-built LED fog light using a Cree Q2 warm white LED (not a cool white LED) along with a narrow angle lens or optic (not a reflector) could do remarkably well -- better than a comparably sized incan.

One of the reasons I still love my original optic Inova XO3. Performs well in the fog.

There is a flashlight that is specifically made for fog. It's the Lumaray FL6 Fog. I have a couple of other Lumarays and can attest to them throwing a tight beam. I'd like to try this one but really don't have fog around here to test it properly, still it's pretty neat.

-LT

This very issue came up for me this morning. No one else was up yet except for me and the dog, and I had several small lights sitting on a shelf by the door, so I grabbed a few and took the dog out to take a whiz. The dog, not me. But you knew that.

Anyway, the short story is that I found that beam pattern is everything, and what worked best this morning in the fog is a light that I never got to "love" because of it's narrow beam pattern and spill that's not worth a flip; my SF L1.

So now I have a "fog" light that I can love again, the L1.

this thread is making me want to get a SF M4 CB
or KT4 conversion....dammittt and i just bought a new light:sigh:

Years ago I asked the same question and pretty much it comes down to this -- the light you perceive as working better is going to be used more than the one that technically works better in fog.

There were things listed above that make most lights more usable in fog. Aiming the light lower is a real biggie. Filters block light emission and colored lights were very well discussed above and in other threads (the yellow fog light theory is in some part still going on because people like yellow tinted lights, not necessarily because they work better).

Pencil beam patterns do seem to work better.

However, to put it in a nutshell, fog is basically millions of little mirrors and prisms. Very hard to get throw in those conditions and brighter often just means more reflection and refraction.

Holding the light well below or above eye level helps as well.