Why the need for red lights?

[Alteran]

Wouldn't wearing red tinted goggles be sufficient to block out all non-red light? This would not work as well with white LED's, but it should work just fine with incandescents. It's true that in a "tactical" situation, a filter on the light might be ideal, so as to not attract attention. I'm wondering why I've never seen mention of this, except for ideas on how to prepare for darkness in advance.

 

[nc987]

Can you expand on this, im not quite sure what your asking.

 

[TOOCOOL]

Im sorry but without red lights you can't find ladies of the night

 

[Alteran]

Can you expand on this, im not quite sure what your asking.

Wouldn't it be easier to wear red tinted glasses that filter out non-red light at your eyes, as opposed to having several red filters over different incan lights? With the limited spectrum of LEDs, this would not work as well for them, though.

 

[nc987]

Ahhhh, theres a post somewhere about this in the archives about a guy that made infrared sunglasses or something like that. It was a really neat post that I think described how to make them and offered some pictures that were out of this world.

Heres a related post with some helpful information:

http://www.candlepowerforums.com/vb/archive/index.php/t-60506.html

 

[RCatR]

Putting a red filter over your lightlowers its output and makes you harder to bee seen by a 3rd party while preserving your nightvision. As for IR sunglasses; an old friend of mine used welding goggles at night to get his eyes adjusted to near-IR light so he could see without use of a light.

 

[bfg9000]

The earliest generation night-vision device (gen "-1"?) did preserve darkness adaptation by blocking all wavelengths of light. The price was loss of depth perception from the mode switching mechanism.

The modern equivalent with stereo vision would be wearing dark sunglasses whenever around bright lights, then taking them off and using only extremely dim lights when it was really dark. I'd imagine wearing darkly rose-tinted glasses the same way would work fine, but actually using them while stumbling around in the dark may require some pretty bright lights.

 

[OceanView]

Wouldn't wearing red tinted goggles be sufficient to block out all non-red light?

I'm still not quite sure I understand the significance of the question. Did you mean, for example, if I were out night hiking with my buddies with our lights off, and we wanted to use a light at some point, instead of using a red/red filtered light, we could all put on red goggles and use our really bright light so we wouldn't destroy our night vision? Theoretically, that would be a valid choice as far as preserving your own night vision, but it requires everyone to have red goggles.

There are other drawbacks, too. If you were an astronomer at a star gazing party, using a bright light ruins the night vision and long-exposure photographs of everyone else. And in tactical/military situations, as you point out, a bright light can give away your position to an observer, whethery using NVG or unaided vision. So, there are good reasons to filter your light rather than filter the light entering your eyes.

I believe I read somewhere that bomber pilots in WW II would sometimes use red goggles before night raids if they had to take off before the sun went down. This would give their eyes additional time to dark adapt without having to actually be in the dark.

 

[Phaserburn]

I use a red Fauxton every night to check on my 2 yr old daughter. The wide angle red light never disturbs her, allowing me to move around and adjust covers, toys, etc.

The same red Fauxton, using a single 2032, has been used a couple minutes per night for the better part of the last 2 years!

 

[TITAN1833]

simply red does not disturb night vision???:nana:

 

[hank]

You have two different things going on, with at least three visual systems involved.

--- dark adaptation (look up "visual pigment" and "night vision")
--- color vs. black/white vision (look up "rods" and "cones")
--- circadian clock receptors and melatonin synthesis (look up "blue light" and "melatonin")

This may help on the specific red light question about night vision and dark adaptation (which takes maybe 15 minutes, for the "visual purple" pigment in your eyes to regenerate after a brief flash of bright/white light):

http://home.earthlink.net/~astro-app/horsehead/DarkAdapt.htm

That's a different chemistry than the one that resets your body clock -- different cells in the retina, not the rods and cones --- and different wavelength and light intensity involved. The latter were only discovered in 2001 and are changing all sorts of things.

NASA found it takes only candlelight levels of brightness to set or reset the body clock.

http://www.pnas.org/cgi/content/abstract/98/24/14027

Exposure to {approx}100 lux:
http://www.pnas.org/cgi/content/abs...an&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT

So going to look at a sleeping baby with a red (or amber or yellow or green, but not blue) light will let the kid keep sleeping; using a standard white LED, which is very strong in blue light,
see the LEDMuseum pages for spectra showing the emissions
is likely to set the kid to "morning" and wake the kid up.

Kids and old people are less solid in their sleep cycle anyhow, so more sensitive to this most likely. Those of you in your 20s and 30s won't have noticed any problem, most likely, even using bright white LEDs in the middle of the night.

Your time will come (grin).

 

[gunga]

Does it work to have a strong red filter on a light (ie, minimag red filter) instead of a red LED?

 

[Alteran]

The main purpose for this would be where you have several lights that all have expensive red filters. Surefire filters are pretty expensive (though not compared to the lights), and the infrared ones are just insane.

 

[2xTrinity]

The main situation in which I would use red light would be for astronomy -- there the idea is not to mess up my own night vision, or anyone else's night vision. Also, since that heightened sensitivity is actually needed for observing, using red glasses wouldn't work.

Using a white light and throwing red glasses would essentially limit your visibility to the narrow spot illuminated by the light. Using a red light, with no glasses on, allows you to still use night adaptation to see your way around by dim moonlight, or astronomical observations, but to also use your red light for specific tasks (such as reading a map etc).

IHMO the best way to go with red light is a true Red LED emitter. Much more efficient than filtering an incan. IMHO it would be nice if red drop-in modules were available for more LED flashlights, as an hot-swappable option. (similar to swapping filters or bulbs an incan, someone could swap the emitter in the field)

 

[bobfried]

Wouldn't wearing red tinted goggles be sufficient to block out all non-red light? This would not work as well with white LED's, but it should work just fine with incandescents. It's true that in a "tactical" situation, a filter on the light might be ideal, so as to not attract attention. I'm wondering why I've never seen mention of this, except for ideas on how to prepare for darkness in advance.

That made no sense at all. Are you suggesting that someone would put on a pair of red sunglasses to use a light at night to preserve their nightvision? For all practicality it's MUCH easier to use a light with a red filter. Why on earth would you want to fumble around at night for glasses, put them on, turn your bright flashlight on, look around, turn them off, take your glasses off than resume what you were doing?

The reason no one does that is because it's impractical. I used red filter quite abit in the military, but even without a tactical situation I would do the same if i wante to preserve my night vision. Again I can't think of a single situation where what your suggesting would make any sense.

 

[DM51]

If you want the best of both worlds, wear a light-proof eyepatch (or a piece of black adhesive tape) over your master eye while you are using a light (just closing the eye is not sufficient). Take the eyepatch off after you've switched the light off. The eye that was covered will have kept its night vision.

 

[Alteran]

...Again I can't think of a single situation where what your suggesting would make any sense.

I guess it's not as practical as I originally thought, but it would be cheaper than buying many red filters in some cases.

 

[bobfried]

Why would you need more than one dedicated red light source? Honestly you do not need nor want any high output halogen, xenon, led, hid or anything fancy. A basic military angled flashlight with the 4 color lens filter kit for $12 is more than enough.

I have seen those red filter's on Surefires and have to wonder why? Sort of like buying a Ferrari Enzo than limiting yourself to 30 miles per hour all the time. Even the new Pentagon Molle is a better setup. A red light source isn't something you'll be using for any serious lighting, it serves as a reading aid at best and some light tracking/navigation uses at night. You do not want it more powerful than a dim faint red light.

Especially when your a lady working the red light district, gotta keep the copper away. :candle: :twothumbs

 

[2xTrinity]

double post, ignore

 

[2xTrinity]

Honestly you do not need nor want any high output halogen, xenon, led, hid or anything fancy. A basic military angled flashlight with the 4 color lens filter kit for $12 is more than enough.

The LED option really isn't bad either, it doesn't need to be too expensive, and it has the advantage of being more efficient than using an incan with a filter in terms of battery life. Around $12 for a Dealextreme "Elly" AA flashlight, and a Red Lux-III LED. Runs a few hours at usable output on 1xAA. The reflector defocuses the light to make a wide flood (bright hotspot would be unwanted), which is useful for say, setting up a campsite or something without disturbing others as much.

If that is too much, I have a red Photon-III with built-in dimming -- more than enough to read up close or something.