Red spotlights


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stressed
November 5, 2013, 10:49 PM
Someone please school me. What's with the red filter lens for spotlights or the red LED's for hunting on the side of some commercial spotlights. What's with the red light? Why no just use the standard white light, you would see the animals better. Is it so other people don't notice it as fast? Animal, especially nocturnal, is gonna see either or.

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MCgunner
November 5, 2013, 11:06 PM
Red won't spook hogs like white light will. I assume they cannot see in red quite so well.

RetiredUSNChief
November 5, 2013, 11:20 PM
Aboard submarines, during night time operations Control is "rigged for red" (the actual term is "rig for low level lighting", but the slang term is more descriptive), and the OOD wears red glasses.

The purpose of this is to preserve the OOD's night vision so that any trips to Periscope Depth or the surface are not delayed or unnecessarily rendered dangerous because he cannot see what's up there. It takes human eyes about a half hour to fully adjust to night vision after exposure to bright light. So human visual acuity is limited during that time.

The same principle applies to any similar night time lighting scheme...the point is to be able to see the best you can without temporarily blinding oneself to the darkness by using broad spectrum white light. Red or blue light is typically used for this purpose. Illuminating a scene with red light does not massively screw up the sensitivity of the human eye like bright or white light does.


I imagine some animals would be less affected by red light than white light, as well.

Patocazador
November 6, 2013, 04:58 AM
I've got a head light with white, red, blue and green bulbs (LEDs). I can see well with the white and green but the red and blue are dangerous for me to use in the dark. They say blue light helps "you" see blood trails better .. maybe it does for "you" but it doesn't for me.

Outlaw Man
November 6, 2013, 09:14 AM
Scientifically speaking, the rods in the human eye are less sensitive to red wavelengths. In application, this simply means that red light is less likely to dilate your eyes and make it more difficult to see in low light. Red preserves your "night vision" better than other colors.

I'd imagine hogs are similar and that's why it doesn't spook them as much.

Chief, you never see that stuff in movies!

Jitterbug
November 6, 2013, 10:06 AM
Predators will typically keep coming to the call with a red light on them, pop the red lens off and go to white when they are within range, this will usually stop them offering a shot. If not I mew at them like a cat or bark like a dog...that always works.

The way I do it this is a 2 man job, one guy running the light the other the rifle, it's really fun when you call in a Mountain Lion or a bear.

Art Eatman
November 6, 2013, 11:21 AM
A red lens cover reduces the tendency of a predator to spook and not come to a call. Even then, I just use the edge of the beam, just enough light to make the eyes show.

A quick flick of white or red directly on a coyote won't necessarily scare him away, but a sustained beam will.

The belief is that they don't see a red light as well, and that's apparently borne out by results.

Patocazador
November 6, 2013, 12:22 PM
I know a gator will submerge quickly with a white Q-beam on him. ;)

brainwake
November 6, 2013, 05:45 PM
I have one of those Primus blood tracking lights..it uses a combination of red and green. I have to admit. It does make blood stand out better. I have used it to track a blood trail at night.

But the light itself is a bit bulky and has something rattling, so it doesn't come along anymore.

The Fenix LD20 does the job for me now.

RetiredUSNChief
November 6, 2013, 08:18 PM
Scientifically speaking, the rods in the human eye are less sensitive to red wavelengths. In application, this simply means that red light is less likely to dilate your eyes and make it more difficult to see in low light. Red preserves your "night vision" better than other colors.

I'd imagine hogs are similar and that's why it doesn't spook them as much.

Chief, you never see that stuff in movies!

Yeah, the differences between reality and the movies is pretty interesting. Well...except for my wife who absolutely HATES to see military movies with me. I have a tendency to go MST3000 on these differences, which annoys the bejeebers out of her.

:neener:

By the way...eyes naturally dilate in low light/darkness to allow more light into the eyes. When exposed to bright light, the pupils constrict, which limits the amount of light entering the eyes.

The response time of the pupils with respect to dilating in low light is only part of the reason for the long time it takes to adjust to low light conditions...and an insignificant one, at that. Pupils actually dilate and constrict very rapidly. However, the cells which make up the retina take a much longer time to adjust to low light conditions, having essentially been "saturated" with bright light. The response time for the rods in the retina are what accounts for that 30 minute adjustment time to obtain maximum sensitivity to low light conditions.


Eyes are fascinating...I wish mine still worked like they did when I was younger! Being near-sighted isn't much of a problem...but having to get a new prescription every couple years or so for changing vision is a royal pain in the keister. Especially that whole presbyopia thing. ;)

Flintknapper
November 6, 2013, 09:49 PM
^^^^^^^^

USN above is spot on with his explanation.

Additionally, (and I am sure he knows), night vision (in humans) is largely controlled by a biological pigment in the eye called Rhodopsin (or Visual Purple).

This 'pigment' is extremely sensitive to light and photobleaches instantly when exposed to full spectrum white light. It does indeed take about 30-45 minutes for the eye to regenerate Rhodopsin...(and night vision be restored to full acuity).

Red light (especially of low intensity) has much less effect and allows the human eye to retain as much acuity as is possible.

If you plan to hunt with a red light, be aware that 'filtered' light is less effective than true 'wavelength' red light.

It has been my experience that canines are least 'likely' to notice red light. Certain other varmints/furbearers (I.E. Raccoons) also tend not to react to red light.

Hogs are another matter. Please do NOT let anyone tell you that red (or any other color of light) is 'invisible' to them, complete BS! Yes, they do not see red as we see it (hogs are Dichromates), but they DO see red light (as some shade of gray).

Light INTENSITY and the Angle of Incidence will determine whether or not hogs will see (and react) to light cast upon them. Hogs are quite sensitive to any light source that suddenly creates a 'shadow' beyond or near them. This is owing simply to the way they perceive things (visually), which is very different from humans.

stressed
November 8, 2013, 02:56 PM
So in effect, if I am wearing red lens glasses, I won't be bothered as much and readjust by oncoming traffic's headlights at night?

RetiredUSNChief
November 8, 2013, 04:02 PM
So in effect, if I am wearing red lens glasses, I won't be bothered as much and readjust by oncoming traffic's headlights at night?

True...however, you may deprive your eyes of other visual cues while wearing them because the red lenses will block/reduce other light.

On submarines, the OOD will remove his red lensed glasses when he uses the periscope for just that reason.

Sometimes blocking or reducing certain wavelengths is great, other times not so great. Blue blockers are awesome for almost any use, day or night.

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