Many people like a red beam for preserving night vision. I don’t want to get into the red v green debate. My question is about seeing further in mist and fog. The sun looks red at sunset because the red rays are better able to penetrate through particles in the air. Therefore it would seem reasonable to expect a red beam on a headlamp to cause less scatter in fog conditions.
I don’t have any lamps with a red beam, perhaps those who do will share their thoughts and observations on this. I’m not very interested in preserving my night vision, but seeing further in fog could be very useful. Also has anyone ever used a “selective yellow” filter (like on car fog lights) on a headlamp?
Quote: “But green was the best when see through fog isn’t?”
Green? That sounds strange to me. I’m not saying that you are wrong, just that it seems counter to my (admittedly slender) knowledge of physics. To my understanding, the longer a wavelength is, the more penetrating power it has. Red being the longest visible light has the most penetrating power, but the eye is least sensitive to red. Blue is the shortest wavelength and scatters light the most (hence the blue sky). Green is the next shortest, and so I would expect it to be the second worst for scattering light. Green is also the easiest to see, the eye is most sensitive to green. Yellow is the second longest wavelength, it should in theory scatter less than green, but more than red. However, the eye is more sensitive to yellow than to red. So yellow is a compromise. Yellow sits half way between easy to see, but high scattering green, and hard to see, but low scattering red. And that is why yellow is used for fog lamps.
I don’t have a degree in physics, or any special knowledge, so the above may just be bull dust. But that is the way I think it through in my own head.