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Thread: Does warmer light better penetrate fog?

  1. #1

    Default Does warmer light better penetrate fog?

    Trying to decide between ZL H600fc and H600fd. To be used in a foggy environment.

  2. #2

    Default Re: Does warmer light better penetrate fog?

    Based on my understanding of the many arguments/discussions that have taken place regarding this subject: warmer tint reduces glare and a narrower beam (more spot and less spill/flood) reduces glare.

    So it often is not that a warmer beam penetrates more than a cooler beam, but that we can see better with the beam that produces less glare.

    Both lights you mentioned have floody beams, so regardless of their tints, neither will serve you well in fog.
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  3. #3
    Flashaholic* emarkd's Avatar
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    Default Re: Does warmer light better penetrate fog?

    I can't quote you the science on it like some of the smarter folks here (who will probably be along eventually), but in my experience a warmer tint definitely has less glare in a hazy/foggy/smoky environment. I don't have any great thrower pictures to illustrate it, but consider these two images of big triple flooders:

    1. Olight SR Mini, 3x XM-L2 cool white:



    2. Custom 3x XP-L @ 4k:



    Both of those photos were made at the same time, under the same conditions, at roughly the same total output. But hopefully you can see that the cool white Olight has more glare than the warmer XP-L light. Specifically look in the upper left corner because that's where the light was held in relation to the camera.

  4. #4
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    Default Re: Does warmer light better penetrate fog?

    Light of shorter wavelength (violet/indigo/blue end of the spectrum) scatters more so does not penetrate as well as longer wavelengths (yellow/orange/red end of the spectrum).

    The proof is simple. In fog or smoke, look back as you walk away from a white light. It'll look more yellow, then orange, then red as you get further away.

  5. #5

    Default Re: Does warmer light better penetrate fog?

    Quote Originally Posted by Yamabushi View Post
    Light of shorter wavelength (violet/indigo/blue end of the spectrum) scatters more so does not penetrate as well as longer wavelengths (yellow/orange/red end of the spectrum).

    The proof is simple. In fog or smoke, look back as you walk away from a white light. It'll look more yellow, then orange, then red as you get further away.
    Very informative.
    Thank you!!!


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  6. #6
    Flashaholic BugoutBoys's Avatar
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    Default Re: Does warmer light better penetrate fog?

    Yes it does penetrate fog.
    Sometimes life is about risking everything for a dream no one can see but you

  7. #7

    Default Re: Does warmer light better penetrate fog?

    You want to see a "glaring" example of this. In HEAVY valley fog in our CA central valley car headlights are practically useless. The insanely orange sodium street lamps cut through the fog like a hot knife through butter. They seem to be actively replacing sodium lamps now with LED of course

  8. #8
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    Default Re: Does warmer light better penetrate fog?

    Quote Originally Posted by mntbighker View Post
    . They seem to be actively replacing sodium lamps now with LED of course
    Haha thats happened here in the uk too ! Complete pants at this time of year.

  9. #9
    Flashaholic* D6859's Avatar
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    Default Re: Does warmer light better penetrate fog?

    Quote Originally Posted by Yamabushi View Post
    Light of shorter wavelength (violet/indigo/blue end of the spectrum) scatters more so does not penetrate as well as longer wavelengths (yellow/orange/red end of the spectrum).

    The proof is simple. In fog or smoke, look back as you walk away from a white light. It'll look more yellow, then orange, then red as you get further away.
    As a mathematician I can't help liking arguments provided with a proof. +1 on this one
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  10. #10
    Flashaholic* grnamin's Avatar
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    Default Re: Does warmer light better penetrate fog?

    I was stationed in Italy from 1987 to 1991. There were a lot of cars that had selective yellow headlights. They cut through the northern Italian fog very well. Fog is usually whitish in color. White light will accentuate the fog while yellow light will cut through it.
    -Greg

  11. #11

    Default Re: Does warmer light better penetrate fog?

    Quote Originally Posted by ShayAllen View Post
    Trying to decide between ZL H600fc and H600fd. To be used in a foggy environment.
    ----
    specs:
    ZLH600Fc Mk 3

    LED: Cree XM-L2 EasyWhite (Typical CRI: 83-85, Nominal CCT 4000K)


    ZLH600Fd Plus
    LED: Cree XHP50 Neutral White (Typical CRI: 93-95, Nominal CCT 5000K)
    --------

    I would pick the one with higher CRI, even though it is 5000k

    note that the following photos, which are excellent imo, the first pick is about a 6000k led (correction if mistaken please), so it exaggerates the difference you will have when comparing 4000 to 5000k. Also the 5000k Zebra is 93CRI, while the 6000k pictured first below is probably only 70CRI.

    CRI is more important than color temperature! Thats my opinion, and Im standing by it with my flame suit ON!

    CRI is my friend. It makes less blue glare, because it is a more balanced spectrum, including a higher proportion of red rendering. Red in Fog is your friend also, it goes into the fog, instead of bouncing back at you as glare from a cooler, lower CRI led.

    My vote is for the ZLH600Fd Plus

    when using a light in fog, the closer to the ground it is, the better. That means you will have some advantage if you shield the top of the light with your hand, so there is less light aiming upward into fog that reflects to you at eye level. Also aim the light at the road, not the sky.. forgive the stating the obvious.. I can get that way sometimes.. LOL
    Quote Originally Posted by emarkd View Post
    1. Olight SR Mini, 3x XM-L2 cool white:



    2. Custom 3x XP-L @ 4k:

    Quote Originally Posted by mntbighker View Post
    You want to see a "glaring" example of this. In HEAVY valley fog in our CA central valley car headlights are practically useless. The insanely orange sodium street lamps cut through the fog like a hot knife through butter. They seem to be actively replacing sodium lamps now with LED of course
    good example, the sodiums are 3000k and have very high Red Spectrum output
    the LEDs are 6000k and are very LOW Red Spectrum output and lower CRI and narrower spectrum than the sodiums, which are a form of incandescent, that his a hot glowing metal element that is putting out black body radiation (broad spectrum)

    again you see the theory Im suggesting that is a priority variable is CRI, which is why I would buy a 5000k 93 CRI light, before a 4000k 83 CRI light.

    LEDs are extremely poor sources of red light, they are much more blue, and are marketed on the fact they are more efficient, that is use less electricity for a give amount of brightness. The fact cities adopt them is for cost savings, not color quality.
    Last edited by jon_slider; 10-28-2016 at 01:20 PM.

  12. #12

    Default Re: Does warmer light better penetrate fog?

    A pure thrower held at waist level is a good light to have for fog. The warmer the better. Spill just lights up molecules nearby (causing glare others mentioned) where a thrower appears to drill a hole better. Does it? Probably not, but when all those nearby molecules are lit by spill you cannot see how far the beam throws as well due to lack of light vs darkness.

    Notice that many fog lights are below headlights on automobiles?

    Recently I did a completely unscientic test where I had throwers, combos and a flooder with me on a foggy night. I could see much farther in the distance with low powered (in 016 terms) (150-200 lumens) pencil beams than with mid powered (400-700 lumens) wide spot combo beams and the 415 lumen flooder was just ridiculous.

    All were tinted at the cool end.
    A 160+/- lumen incan Maglite focused to pencil lead beam won the contest.

    Now for kicks and giggles I stood at the other end of the beam some 250' away.... I could the output end of each flashlight at that distance with the brighter ones appearing brighter than the lower output ones. And I could see the cooler beams better than the incan one.

    So I'd say for self defense or safety the warm pencil beam is your friend from the user end but... also lends a hand at keeping your foe from see-ing you as well. Win-Win.


    Where I was the pic shows lots of fog in the distance. That was where I did the unscientific testing in the nearby woods.

    I also noted the farther towards the ground I held the light away from my eyes the better I could see at a distance. Waist carry was comfy to walk and much better to see by than above the waist or over my head as high as my arms could reach. Over head was better than eye level though.
    Last edited by bykfixer; 10-28-2016 at 02:31 PM.
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