Whether a warm white emitter gets more light downrange due to less scattering/absorption vs the higher output of cool white is one issue, but it’s undeniable that cool white lights cause WAY more backscatter than the usual 10-15% output advantage would suggest and we have the science that explains why.
Cameras don’t function exactly like human eye does in many ways either, so while those pictures might be accurately showing what the human eye would see, they also might not be.
As for my personal experience, yellow sunglasses and flashlights have always seemed to provide more contrast, less glare, and more clarity while being easier on the eyes.
While I agree, that’s caused instead by the eyes sensitivity to blue light causing strain/constricting pupils more, and very likely due to the wavelength of blue light itself being harder to focus on. An easy demonstration of this is to set up a red light and blue light of equal size and relative brightness at night and look at them from a distance. The red light will be easy to focus on and “sharp”, while the blue light will appear “fuzzy” as with certain conditions (like pupil dilation) it is difficult for the human eye to physically get a good focus.
Raleigh scattering is for particles much smaller than the wavelength of the light and is stronger for shorter wavelengths. This is why the sky is blue; light scattering off air molecules.
But fog particles are several microns large, larger than the wavelength of light, and this scattering mechanism is called Mie scattering, which has little wavelength dependence. This is why clouds and fog look white and not blue.
We need some controlled experiments and photographs. I have seen photographs appearing to show both cases, cool light scattering more, and cool light scattering the same.
In a nut shell this is why I told Hank to make an aspheric bezel/lens for this light.
You guys are worried about micro particles in the air? The white hull of the boat I was on was a much bigger obstacle to my vision than the horrible fog we were in. The spill from the light reflecting off the hull of the white boat I was riding seemed worse than the back scatter from fog. If you are truly interested in seeing long distances you don’t need your feet lit up and pupils constricting while you are trying to spot something far away.
Agreed. But I think scattering off particles in the air is usually significant if not dominant, and that source of scattering would not be wavelength dependent.
All I can say is that in my experience and from many beamshots I’ve seen cooler light of the same focus and brightness has far more backscatter. I’m sure there are many variables to it though.
I have had the same experience. I much prefer warmer tints in my bright, outdoor-use lights. When standing directly behind the light, the scattering from the beam of a cooler tinted light can sometimes completely obscure what you are trying to illuminate. The beam is still visible with warmer tints but the glare seems to be much less prominent.
This is the same reason many people complain about glare with newer HID and LED car headlights that tend to be in cooler tints than your standard halogens.
For me, it’s definitely that the visible backscatter interferes with my ability to see, not that it seems like less light gets to the target. The effect is not significant if I’m looking from a position a couple degrees away from the light source, but that’s longer than my arms in situations that call for a thrower.
It’s a foggy night outside so I took my E07 SST-20 2700K and E07 XP-L HI 5000K outside for the test. I was surprised their reach is about the same. Though the XP-L HI was about double the brightness due to fresh batteries and brighter emitter. When using the 2700K, I get the impression that it penetrates fog better because I don’t see as much fog moving. With the 5000K, the moving fog is much more visible and it takes my eyes a few seconds to adapt to the glare to be able to focus in the distance whereas with the 2700K, I can pretty much see into the distance right away. But the amount of detail and the distance I can see seems identical with both lights to my surprise.
I think a 2000K flashlight might actually make more noticeable difference in fog.
I think a 2000K flashlight might actually make more noticeable difference in fog.
Now that is something I would buy. I lived off the coast of Washington ST. called Anacortes. Its located on Fidalgo Island, in the Pacific Northwest. It is conveniently situated halfway between Seattle and Vancouver BC and is the destination point for the San Juan Islands and International ferry runs. The fog there would get so thick it was like something out of a movie. You could feel it in your lungs it was so thick. I would be very interested in a torch designed just for fog with maybe an adjustable tint if possible.
Then you’d have to go with incan lights. LED produces one color of the spectrum (monochromatic), while incan emits all colors, making them better to pierce through smoke and fog.
Uh, no.
Monochromatic means one wavelength… that’s what a Red LED does for example, at maybe 635nm.
Or a laser, for example 532nm for a green one…
But a white LED emits all visible wavelengths… in a different way than an incan bulb of course, or even the sun
He’s sorta right. The LED is very much just blue light. Only after it’s put under a yellow phosphor with a broad spectrum does it emit what looks like white light.
I have taken photos from behind the beam as well as far off to the side. The beam shots proved to me that a more neutral white (and I do mean an absence of color) shows best. This is, of course, what works for me, in my settings and usages. I throw away any emitter under about 4750 and over 6000K.
(And I use the best cameras and lenses I can afford. The shots posted of the water tower are using about $7000 worth of camera and lens)
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