I’ve read several posts about which flashlight is better on a foggy/drizzly night, neutral white or cool white. Some say neutral white penetrates through the fog/drizzle better, others say cool white is better. I thought since I have both a neutral white and a cool white Sunwayman D40A, I would test it out for myself. Here’s a review of the Sunwayman D40A for those unfamiliar with the flashlight. The flashlights were purchased back in 2014 within weeks of each other from the same supplier (anyone remember Doingoutdoor?). The neutral white is rated at 980 lumens and the cool white is rated at 1,020 lumens. They throw pretty well for being stock 4xAA flashlights.
I used fully charged eneloop batteries (from the same batch), placed the flashlights on my deck railing, and put them on turbo.
Here are some pictures showing the fog/drizzle.
Here are some pictures lighting up a hill in my backyard, which is about 120 feet away.
Here’s a zoomed in picture of the hill.
Can you see a difference? Beyond the tint, I did not notice a perceivable difference between the flashlights.
Thanks for reading and any comments/questions are always welcome.
Cool :+1: I think it’s just that cool white is more blinding when reflected back at you from the moisture in the air. Looking at the pictures can’t see much difference other than tint. Haven’t tried a comparison myself.
Thanks for the comparison. I don’t see a difference in visibility, but as mentioned above it could be that cool white gets reflected back more. I hadn’t thought of it before, but it seems like 20-30 years ago car “fog lights” were tinted yellow. I don’t notice that as much now days.
Ollie more or less ninja’d me. Cameras perceive light differently from the human eye, so what looks equal in a photograph can have vast differences in person. Also don’t the spills overlapping interfere with the exposure?
Generally speaking, a warmer light will outperform a colder light in terms of the “bounce back” effect. There is a scientific reason why. Light that we call “colder” is a higher frequency. Light which is a higher frequency will have a higher incidence of refraction. You can even see this effect happening in images of prisms, which demonstrate refraction. The “warmest” colors have the least refraction.
And yes, in the past “fog lights” were traditionally yellow because they refract less than “white” lights. This has changed in recent years because people decided that yellow fog lights look ugly. The recent change is purely aesthetic and not at all functional.
If you really want to see a dramatic difference in refraction, you’d have to compare an old incan light (like an old 4D Mag) and then find a cool white LED flashlight which was similar output (maybe something with a 60-80 lumen mode). The difference in the light spectrum of an incan vs and LED is night and day. You also need to take into account that “color temperature” is really just a representation of “average color frequency” of a given light spectrum but it doesn’t represent the differences in the spectrum itself per se. Two lights coming from different sources could have the exact same color temperature but very different spectrums.
Thanks, NeutralFan, for the pictures. It is often stated that warmer color temperature lights will scatter less and work better in situations with fog/moisture in the air. But I haven’t seen many direct comparisons like you have shown in the OP. It is clear from the pictures that there is no significant difference in scattering between your two lights, with those atmospheric conditions.
I think this belief that warmer colors scatter less is based in the phenomenon of Rayleigh scattering, in which light scatters from particles much smaller than the wavelength of the light. In Rayleigh scattering there is a strong dependence on the wavelength of the light; shorter wavelength (more blue) light scatters more than longer wavelength (more red) light. This phenomenon is the reason the sky is blue; the blue parts of the solar spectrum scatter more from the air molecules in the atmosphere.
However, the typical particle size in fog is much larger, around 1 to 50 microns which is larger than the wavelength of visible light. In this regime of particle size scattering is called Mie scattering, and it is roughly independent of the light wavelength, so warm and cool light should scatter about the same from fog in the air.
So, it is my understanding that if it is a very clear night with possibly some very small dust particles a warmer light would scatter less, but with fog or moisture different color lights scatter the same. It would be interesting to see some more direct comparison beamshots.
Rayleigh scattering occurs on scattering centers which are much smaller than the wavelength of light (typically the air molecules).
… Mie scattering in contrast occurs for much larger particles (water droplets for instance).
Atmospheric light scattering - FlightGear wiki http://wiki.flightgear.org/Atmospheric_light_scattering/
“Mie scattering (sometimes referred to as a non-molecular or aerosol particle scattering) takes place in the lower
4.5 km of the atmosphere, where there may be many essentially spherical particles present with diameters
approximately equal to the size of the wavelength of the incident energy.”
Nice test, well performed, you convinced me ! I like it when long known ‘facts’ are actually tested, even better if they appear not to be true :partying_face:
Note the Mie scattering is the reason those blue-white headlights appear as a blinding onrushing fogbank when encountered on the highway.
I always figure if the car owner had the slightest clue how those bright blue lights affect oncoming drivers — especially older drivers — they would rip them out right away.
I know there’s an oncoming car in that massive approaching glare somewhere, but I can’t see the median line or the shoulder of the highway, so I’ll just guess … ZOOM …. whew!
I’ve always loved warm white in fog or rain. I think it reflects less. It could be just perception, but it seems real, and the warm light in those conditions looks great.
NeutralFan, thanks for showing this test. I was thinking of doing something similar, but mosquito season is in full throttle here, and night is only something I venture out in either a car or a bicycle (going faster than bugs).
I’ve got a 7A tint (in a C8 thrower) coming, and I plan to do a similar test. A 7A tint is close to 3000K, while the D40A neutral white is around 5000K iirc. So, maybe one of the reasons there isn’t much difference in your pictures is because the tint isn’t different enough? I’ve read the other explanations, and they’re good, but I’d still like to see a side-by-side with 2 very different tints. Like, 3000K and 6500K. I might also throw in an old 4-cell incandescent Maglite for comparison (zoomed in for throw).
Personally, I like warm tints indoors, and cooler neutrals (5000K) outdoors. But that’s probably just my brain thinking the 5000K is clearer. I know that cooler than that, things start looking too washed out and ghostly for my tastes.
Logic tells me that warm tints should actually be better outdoors. Not just because of scattering (if that really is an issue), but more because a lot of summer/autumn colors are reds and browns. Those colors will show much more contrast when illuminated by a warm tint (even at the same CRI as a cool tint). The downside is less lumens from a warm LED, generally.
Just wanted to add that the photos represent what I saw in real life. I also took both flashlights and pointed them at a faraway tree and again saw similar results.
light closer in the yellow band of the color spectrum is less glarey to our eyes than light close to the blue light spectrum. (meaning why for decades automotive fog lights have had amber/yellow lenses.) Warmer light always seem have less glare irritation to the eyes from the reflected light from fog (or snow) at night. sort of causing less eye-squinting from the easier to look at warmer reflected light, allowing us to focus better on objects in the distance. The difference between a 2700~3000K warm white Flashlight and a 6500~7000K cool white flashlight beam in fog or a snow blizzard is very noticeable with the warmer light being much less eye glare.
I like it when long known ‘facts’ are actually tested, even better if they appear not to be true :partying_face: