Purpose of blue light?

I bought a Photon Freedom with a blue LED a year or two or so because it was really cheap compared to the white LED version. I carried that thing for months, but eventually got tired of it and got a white LED. The blue light just never seemed to be that useable and irritated my adjusted eyes almost as much as white light.

Anyway, my question is: what is the purpose of blue light? I know that red lights are used to protect night vision, but why would anyone prefer a blue light?

Im not 100% sure but I think you can use Blue to make it easier to see blood.

Beamshot said:

Im not 100% sure but I think you can use Blue to make it easier to see blood.

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I've heard it could be used for other fluids too.

I have a Surefire FM26 blue filter. But mainly got it to protect the lens on my Surefire M6.

(Got it at a huge discount from a former Surefire Authorized Dealer who lost that status).

incan yellow = not cool
led white = cool
solid blue = win

richardcpf said:

incan yellow = not cool
led white = cool
solid blue = win

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You mean you like blue light better than white? Why?

concept0 said:

You mean you like blue light better than white? Why?

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It was sarcasm

Blue light = special
Red light = Roxanne
Dashboard light = Paradise

etc. :nana:

concept0 said:

I bought a Photon Freedom with a blue LED a year or two or so because it was really cheap compared to the white LED version. I carried that thing for months, but eventually got tired of it and got a white LED. The blue light just never seemed to be that useable and irritated my adjusted eyes almost as much as white light.

Anyway, my question is: what is the purpose of blue light? I know that red lights are used to protect night vision, but why would anyone prefer a blue light?

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Hunters do use blue light for tracking wounded prey.
Blood shows very good, you can see small splatters on leaves, trunks, on the ground, very easily.

Is blue light used for map reading as well or is that something else......

White light is for general use
Red light preserves night vision
Blue light is used by hunters for tracking prey, and also I believe projects better in fog or mist than a white light.

Red is what will be used for map reading in the dark usually, as it won't destroy your night vision. As a note, most large scale maps (currently looking at a 1:7500 map) don't use red in the markings, so a red pen is used to make notes without obscuring details - Red is often used in roadmaps and on larger ordnance survey maps (this is in the UK, I have no idea what the US equivalent is...)

In my experience red light preserves night vision fairly well, and the dimmer it is the better.

As far as tracking blood goes, last year I tried this out in the pitch dark on some fresh gore from a deer kill with both a blue LED and blue incan with a filter. Neither light had any significant effect on the blood that I could see.

It appears to me that the blood tracking ability of blue light is a hyped-up feature intended to sell more lights to pessimistic hunters. Their best bet would be to stop shooting earlier in the day and take care of business while the sun is up.

If you want to track bodily fluids a blue light is a waste... a nice UV led light with a pair of yellow UV glasses is the only way to go.


Blue lense filters are good for making your kids think they have a light saber on foggy nights. :twothumbs

The only 2 uses for a blue led alone that I've found are dusting (makes the dust stand out a LOT) and help waking you up (don't shine directly in eyes, use a diffuser). I've tried ketchup on leaves and used a blue led, really doesn't help much, use a blue led and a red led at the same time though and it seriously pops out. Also theoretically speaking blue is bad in fog because of Rayleigh scattering.

The best use for blue light in my opinion is for fishing or for use in water. Blue light goes straight through the water without reflecting the light back. You can see through the water as if it wasn't there. Don't use it for hiking in the rain though. You won't be able to see puddles until you step in them. Blue light does work well in fog, but it's a fraction as bright as the light from a white l.e.d.. I've found that a tight beam bright white l.e.d. flashlight will do better in fog than a much dimmer blue light. You need a blue light of equal brightness to a white light for it to be better in fog. Cool white works okay in fog and so does warm white. Pure white reflects back the most. In fog, warm white is nice as it also works well in smoke.

I've read somewhere (probably here) that most blue lights on the market are useless for tracking blood trails. It only works when the blue is within a specific wavelength. Last week my GF was running the vacuum cleaner and she ran over some fishing line one of the cats pulled out of the closet. The vacuum seized up and I had to cut the line out with a knife. This left lots of short bits of line all over the carpet. I was using a ROV 1xAA headlamp and the bits of line just about glowed under the blue beam making cleanup a lot easier. I use P-Line and Yozuri copolomers on all my non-fly rods. I don't know if it would work on regular mono.

ypsifly said:

I've read somewhere (probably here) that most blue lights on the market are useless for tracking blood trails. It only works when the blue is within a specific wavelength.

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UV I think, for blood and some other bodily fluids.

Blue LEDs are great for blinding people.

Blue (high frequency) light scatters most easily, that's why the sky is blue and the sun is yellow. The blue is refracted (scattered) by particulate (dust) in the atmosphere, leaving yellow sunlight. The setting sun goes through more and larger particulate, scattering longer wavelength light, making for deeper reds in the sky and sun. More dust makes more colors, like when there's a forest fire or volcano throwing up more dust.

Blue requires more energy to produce, and carries more energy. I'm working on an LED tester, customer thought I might verify the blue color is installed because it draws more current than the amber. Blue scatters and bounces more in the eye than longer wavelengths, dazzling and irritating. That's why ricers with fake HID headlights are so annoying. Blue scatters readily in fog, so foglights are often filtered to remove blue, leaving amber light. Blue-blocking sunglasses and camera filters take the haze out of hazy scenes, because the haze is scattered blue light. Blue blockers are helpful for older folks with hazy vision.

Dunno about the blood part. Red doesn't reflect blue light well, maybe there will be more contrast in green foliage? Red shows up pretty well with a white light.

Blood will show up well under UV light because it contains fluorescent molecules.

I've been asking the same question about a blue X5 I've had around for a while and can't find a use for. I tried to fluoresce blood, but nothing happened