Blue light???

What is the reason for having blue LEDs in a headlamp or flashlight? Is it a cheap, partial stand-in for UV? Is it used as another color option for signaling? Some other purpose?

Blue light (not UV) is helpful in having blood stand out from the background with more contrast, for tracking. For example, say you are one of the many serial killers hiding in the tall grass, that only kills innocent and helpless hunters, and you miss your mark wounding your quarry but not killing them, and they crawl out of your range, a blue light will help you see their blood trail so you can better track them down to finish them. My understanding is this is an extremely popular sport for sociopathic serial killers. Disgusting, considering that the existence of hunters is becoming so endangered, due to the advent of civilization.


http://www.candlepowerforums.com/vb/showthread.php?214517-Purpose-of-blue-light

Blue light can be used to light your way without giving away your position as readily as a white leaning tint.

Say in war time you want to show your position to nearby comrades, you could signal with your light covered with a blue filter, a green or a red. The lights issued to troops in Vietnam had filters inside a storage compartment in the tail cap.

In the case of hunters, some prefer green to light the path to their tree stand without spooking nearby wildlife as readily (although the critters knew about said hunter long before said hunter was near said tree stand.) At some point blue became a popular tracking color. These days it is part of a marketing campaign to assist sales.
But blue can also be used to read maps or a compass while preserving night adapted vision for hikers who prefer to be guided by stars and moonlight. Especially handy if one is not sure where they are at a given point.

So it has several uses.

I'm sure LEO and others can also tout uses for a blue light.

Blue light is also popular for night fishing. There is conflicting information about why. Probably nothing more than a gimmick.

Hunters are starting to switch from blue for blood tracking to high CRI. Overall it works better.

:thinking:

chillinn said:

Blue light (not UV) is helpful in having blood stand out from the background with more contrast, for tracking. For example, say you are one of the many serial killers hiding in the tall grass, that only kills innocent and helpless hunters, and you miss your mark wounding your quarry but not killing them, and they crawl out of your range, a blue light will help you see their blood trail so you can better track them down to finish them. My understanding is this is an extremely popular sport for sociopathic serial killers. Disgusting, considering that the existence of hunters is becoming so endangered, due to the advent of civilization.


http://www.candlepowerforums.com/vb/showthread.php?214517-Purpose-of-blue-light

Click to expand...

parametrek said:

Blue light is also popular for night fishing. There is conflicting information about why. Probably nothing more than a gimmick.

Hunters are starting to switch from blue for blood tracking to high CRI. Overall it works better.

Click to expand...

Blue helps to make monofilament fishing line stand out in darkness. Truthfully, I rarely use that feature. When night fishing I usually have a Coleman lantern going. So seeing is not an issue.

there are a few wrong info here - lets name it "overdue sosaying"
(no offense intended)

green light for "tricking" night vision equipment ... yes, very early 1st gen. devices could not "see" green light ... as of now: forget that

preserving night vison by using something other than white light, especially the always mentionned red ... proven wrong!
--> it is the amount of light that makes the difference.
low, low light = good. bright light (even red) = kills night vision
so knowing that: anything (especially reading a map) goes better with white light. Just keep it low

blood?
never tried, but in theory: blood with blue light = a black "mark" or "trail", that is not "lightened", while everything else glooms blue ...
BUT
with a white light that blood possibly is simply red and thus (white light = better for most everything) that blood trail is still better to follow?
:thinking:

Blue + fishing line ... no idea.
maybe the plastic is a bit UV active and the blue light also emits some UV?

summary:
the white light - consisting of a multilevel light with a low output - is the best sum of compromises
colors: gimmick

exception: red as warning light in traffic

http://stlplaces.com/night_vision_red_myth/

best explaination I have ever red (heh), even if the site is bit wonky, the essay is superb.

Yet again, tools for whats needed. Blue acts as a black light. As mentioned above, a dark spot for blood, but also anything white stands out. Thus certain colors of fishing line will light up as well as white markers for location purposes. Of course a reflector with a white light can also serve as a marker as well. Using any color besides (presumably bright) white makes it difficult for a second party to locate you. I used to use blue light, but now i have moonlight modes which also work well. I still like the blue for its black light feature though even though i've been toying around with UV drop-ins recently.

Although red may not be the best for vision, again using it makes it difficult for a second party to locate you. In addition, red isn't seen by animal life i've read in the past, but go knows what they see. People have said that animals don't spook when red is put on them. Haven't had the opportunity to experiment with white versus red on animals.

Green is supposed to be the easiest light spectrum for humans to see so it is supposed to contrast better. Although i have some green filters to play around with, white seems to work fine for me.

Do not own one yet but saw my friend used one with white and blue source when go out fishing. it claims that fish will not be disturbed by blue light. also found another function that blue light can make blood and chemical more visible, does it work?

Years ago (mid-1970's), I knew some deputies that replaced the clear plastic lens on their Kel-Lites with a (light) blue tinted lens. When asked, the deputies told me that the blue lens reduced the amount of light reflection when shining their lights through car windows. I didn't see many deputies doing this, so I can't comment on how well it worked.