I’ve heard it was because red light waves don’t travel that far, but I can see the red light on an airplane wing that’s miles away.
In: Technology
Greetings from /r/flashlight.
First of all, “tactical” flashlight doesn’t have a fixed definition – it tends to be more of a marketing term. Most lights marketed as “tactical” don’t have a red LED or include a red filter.
We do see a number of posts from people in various armies asking for lights with red capability though, usually because someone well above their pay grade has mandated it for reducing observability. Oddly, there doesn’t seem to be any limit on output or intensity most of the time, and someone looking upon [this](https://i.imgur.com/4mVvg0b.jpg) from a mile away would easily be able to tell someone is using a light source.
There’s also a perception that red light doesn’t ruin dark adaptation. It’s half-true: at similar intensity, red light will have less impact than white, but it’s harder to see what you’re doing with red light, so it kind of evens out. I’d make the same argument for observability: the most important factors are to use as little light as possible, and avoid pointing light sources directly toward where an observer might be.
Much of this doctrine was likely developed long before the advent of modern LED-based flashlights, which can support dimming between a hundredth of a lumen (literally thirty times dimmer than a firefly) to over a thousand (car headlight). A red filter substantially reduces the brightness of a fixed-brightness white light.
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