Why Incand better than LED under foggy situation?

I found that my PT Yukon's incand performs better than my superfire SF101 (1W LS) in heavy fog. it lights up my trial better than the 1W LS does, but why?

More of the light spectrum in the incan. is reddish (LED bluish). Blue light is attenuated more in moist air; that's why sunsets appear red/orange.

i too realized that my my C2 with a P60 can out-throw my space needle II in misty or foggy conditions.

This is very interesting.

I too have also noticed that my lamp lights work better than LED's in the fog. I thought it had to do with the focus of the beam, but even my TigerLight works better. It's beam has both a focused hot spot and also a lot of spill.

As PhotonBoy brought up, it may have something to do with the spectrum.

I also have noticed that my HID light (990) works reasonably well in the fog, but because of the amount of light, there is a fair amount of back scatter.

Tom

Try warm white LS instead of regular white. I'm using that in one of my Yukons. Amber cuts through moisture even better than warm white, but isn't as bright. In fact, neither is as bright as regular white. That's the price you pay.

Is there some info somewhere on what color lights are best for fog, rain, smoke, etc?

Every opinion about which is the best color has been expressed is past posts and they don't all agree. I'll give my vote to tightness of focus for what most affects fog and smoke penetration.

I think it has to do with Rayleigh scattering of light in the molecules of the air. Scattering is more pronounced in the blue end of the spectrum.

After reviewing the posts here, I think the incand still has their value, as its really foggy these days here.

My experience with red and green lights would seem to indicate that red goes through the fog much better without backscatter.

On the other hand the experts seem to disagree with me.

All I know is that ships at night show a red light on one side and a green one on the other. When it's foggy, the beam of the green one is clearly visible when you're on the ship. The red beam is not visible. Maybe that's just because when our eyes are adjusted for night vision, our eyes are more sensitive to green. I dunno.

Aren't car fog lights yellow?


I'm guessing that yellow works well in fog. Incadescents are yellow brand new, and turn amber to brown as they lose battery power. So, I'm thinking that incadescents yellowish tint works well in fog while the whiter luxeons don't.

We have a lot of fog where I live - especially the intracranial variety. /ubbthreads/images/graemlins/icon15.gif When I've compared my lights, the most tightly focused lights were more useful than brighter but less focused ones. It seems back scatter is less with a tight beam and is less distracting - the image in the spot is clearer. I haven't tested anything but "white" lights so my results my not be valid for other colors.

My fog lights are not Yellow. In fact I think most OEM car fog lights are not yellow, they are white. The Aftermarkets make yellow ones.

I think the incandescents work better because of the ability to be focused tighter. Like the Streamlights with smoke cutting beam, it's like a pencil beam.

LED's are more of a floodlight, giving more light to bounce back from the moisture in the air. If you flood the area with light (LED) the moisture lights up and blocks the view I would assume. With a thin beam, the view is not blocked. Just my guess.

If they could get an LED to focus very tightly with not much spill, it should work just as good.

Well, fog lights aren't tightly focused at all; they are floods. Strange, no? They are, however, usually mounted lower to the ground than the headlights. To me, that means they are trying to sneak the light under the fog.

I THINK some Lexus and Mercedes cars came with Yellow (really Amber) foglights in the early 90s. Really ugly looking but they looked brighter than standard fogs that were facing my directions. It's really annoying seeing those foglights on here in San Diego where it doesn't get that foggy.

Foglights aren't floods. I don't know exactly why that is, but my best guess is NOT to project a farther beam into a foggy night, but to illuminate as much surrounding visuals as possible (i.e. highway markers, reflectors, lines, and side markers such as those bold white/yellow lines or ditches).

I drove once in HEAVY fog a few weeks ago. The ONLY way that i could navigate was by looking 10 feet in front of me at the lines on the freeway, just making sure i didn't stray away from the lines in front of me. Boy was THAT hard with standard headlights. I think foglights would have given me 3 or 4 feet more visibility on the ground...that's it. But those 3 or 4 feet would have been much safer than none at all.

As far as what color to choose...you might want to ask S4MadMan on this forum. He's had experience with some expensive foglights. He use to have HID foglights but had bad luck with them in actuall use. I think the color of the HID did not fare well in fog and the backscatter was bad. I think he switched back to standard incan. bulbs.

I was camping by a lake a couple of weeks ago. Of course I had a bunch of lights with me. That night the fog rolled in on the lake.

I have believed that a tight focused light would penetrate the fog better and my UK SL4 was doing quite respectable. I remembered that I had my 990 in the truck and pulled it out. If I laid it on the dock and stood up, I could see the trees on the other side of the lake. I could not do this with the SL4. If I held it in my hand, I could only see a short distance because of the back scatter.

There seems to be several parts to this. A tightly focused beam should be less bothered by back scatter. A beam that is "off axis" is also less effected by back scatter. It also seems that more power punches through better, if you can control the back reflections. The final part is the color of the light.

An optimum fog cutting light should address all of these things and I am sure I am missing some of them.

Anyone else out playing in the fog?

Tom

Re: Why Incand better than LED under foggy situati

Remember that Amber fog lights on vehicles are not so much for the driver to see with, as others to see the oncoming vehicle!!!!!!!!!! This is why they need to penetrate further than standard headlights.

I get very annoyed at drivers with the 'I can see just fine' syndrome. What about ME seeing You before run run me over???

Re: Why Incand better than LED under foggy situati

The lens on auto foglights is designed to be a flood with the top cut off! Pull your car up to a wall and turn on the foglights and you will notice that there is no upward scatter of the light beam. This reduses the back shine innto your eyes. Yellow light will increase the perceived contrast when viewing objects in the light beam.

Just like with driving lights, having a sharp cutoff of the beam, to prevent scattered light, is whats best. I have found that white is just fine; provided you truly have limited scatter light. The scatter light reflects off the moisture beads in the air and directs the light right back into your eyes. Top quality driving fog lights have a sharp cutt off at the top of the beam to limit the reflected light. I know no flashlight that has a "top" cut off; therefore, a tightly focused beam with little or no scatter is the way to go.

Hey guys, please don't guess, what you guys said OEM car fog lights not yellow....what early '90s MB and Lexus ugly yellow fog light...OH! please
Yellow (Amber)is the first (original) color use in the fog light.

Please read Phaserburn and Roy...etc our CPF experience member for correct information.

ac