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Thread: Red map light: good idea?

  1. #1

    Default Red map light: good idea?

    A long, long time ago, it was commonly thought that red light would do the least short-term damage to night vision. Folks at Pontiac and BMW and others used red lighting for their gauges, presumably for this reason.

    I wonder if that's still common wisdom and/or fact.

    My '08 Prius has a pair of overhead "map lights", using T10/192/168 bulbs. I have the idea of converting one of them to red LED, so if I wanted to look for something at night, it would be less bad for my night vision than the current "cool white" LED map light.

    Is this a good idea, or am I working with outdated information?

  2. #2
    Flashaholic* zespectre's Avatar
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    Default Re: Red map light: good idea?

    I replaced the map lights in my Volt with red LED. I couldn't say if the end result is due to the red, or them being somewhat dimmer than the white bulbs, but now if my wife flips on that light without warning (as is her habit) it certainly has less impact on my visibility as the driver.
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    Moderator Alaric Darconville's Avatar
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    Default Re: Red map light: good idea?

    Quote Originally Posted by eggsalad View Post
    A long, long time ago, it was commonly thought that red light would do the least short-term damage to night vision. Folks at Pontiac and BMW and others used red lighting for their gauges, presumably for this reason.
    Or to "look cool" and with the (hopefully unintended) effect of helping to mask dashboard warning lights.

    Replacing the lights with *not too intense* red would help preserve night vision. Even too-intense red light damages night vision. Some of the red LED ones may be too intense.

    Red light will make maps with red markings harder to read, though.

    In my '01 Corolla, the little map lights in the rear view mirror have been replaced with 194A ('amber') bulbs which are slightly less troublesome than white light. Is it the removal of a lot of blue light, or just the reduction in intensity? One could guess either way, or even that it is the intersection of reduced blue light/reduced light overall.

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    *Flashaholic* StarHalo's Avatar
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    Default Re: Red map light: good idea?

    The only way red light doesn't affect night vision is if it's so dim that you can't tell it's red; 660nm+ and moonlight mode only, most "red" LEDs are ~630nm, and the interior light of your car is certainly not moonlight. You have zero color recognition using a single-color light for a task anyway.

  5. #5
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    Default Re: Red map light: good idea?

    It is 100% fact. Subs rig for red before going to periscope depth for this reason. Pretty much a well established fact in the military circles.

  6. #6

    Default Re: Red map light: good idea?

    I’m slightly red green color blind, so definitely would work for me....

  7. #7

    Default Re: Red map light: good idea?

    Difficult to read/see stuff under red light. You can reduce dark-adaptation damage by attenuating the blue without going all the way to red; put in these (or if you want to experiment with red anyway, use these.)

  8. #8

    Default Re: Red map light: good idea?

    Once upon a time I switched my car's map lights to red bulbs. I left it like that for years but really it wasn't a good idea. Reading maps or general purpose, it's just too hard to see details. Blue lights are recommended for nighttime reading of maps specifically, they don't impact your night vision as much while also don't wash out markings on the maps. But I doubt these days you use your car's map lights to actually read maps. For a softer general purpose use, I like Virgil's recommendation of an amber light.
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  9. #9

    Default Re: Red map light: good idea?

    "Blue lights are recommended"...by who? Blue is not a good choice for nighttime seeing. It has the largest negative impact on your dark adaptation.

  10. #10

    Default Re: Red map light: good idea?

    We have two types of photoreceptors in our eyes: rods and cones. Cones come in three basic types: mostly red-sensitive, mostly green-sensitive and mostly blue-sensitive. (That's why we have Red-Green-Blue, RGB, monitors and TVs. Combining these three colors at different intensities is perceived as different colors of light.) Rods are 100 times more sensitive to light, but don't register color. Both rods and cones become desensitized in bright light, and in dim light--if they have not been desensitized--only the rods are sensitive enough to work. One of the several proteins involved in vision--rhodopsin--in rods is not sensitive to red light. So, we can use bright red light that is perceived by the red cones to illuminate things reasonably well without desensitizing the red-insensitive rods we need to see in very dim light. In other words, red light helps preserve night vision (the ability to see in very dim light) because it doesn't desensitize rods the way higher-frequency colors of light do.

    Using a red map light lets you use lots of light to read the map, then use very little light to hike the trail, see the road or stumble to the bathroom.

    By the way, I am a Scoutmaster, and I encourage my Scouts to use the dimmest possible setting on their flashlights, and to be careful not to shine them in the eyes of fellow night-walkers. People are often surprised at how well they can see if they let their eyes adjust to the darkness, how quickly they can lose night vision with a burst of bright light (including the reflection of high-beam flashlights off trees or buildings or fellow campers), and how long it takes to recover. It takes five minutes to recover the majority of night vision, and almost an hour to fully recover it. When we are stargazing, I use a dim red light, and have people notice the difference in how bright the stars seem when we start, after five minutes, and after 20 minutes. Some people never see many stars, because they never let their eyes adjust enough to let the starlight register.

    If you have ever woken in the middle of the night to go to the bathroom, you may have noticed how much brighter the path seems than when you went to bed. That's because the proteins responsible for night vision have had a chance to return to full working order.

    Hope this helps!

    Joe Gill

  11. #11

    Default Re: Red map light: good idea?

    Quote Originally Posted by -Virgil- View Post
    "Blue lights are recommended"...by who? Blue is not a good choice for nighttime seeing. It has the largest negative impact on your dark adaptation.
    I wasn't saying blue was a recommended nighttime light. I said it was for nighttime reading of maps because the color doesn't wash out markings (compared to red or other colors).

    Back when I got my SRT9, it had red, green, blue, and UV modes. I was well familiar with the uses of red and UV and I'd heard about using blue to see blood trails but I wasn't sure what the practical purpose was for green. In researching it, using blue for maps was one of the other factoids I gathered. Here's one reference a quick google search comes up with; there are others:

    http://www.flashlightuniversity.com/...lors-and-uses/
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  12. #12

    Default Re: Red map light: good idea?

    Quote Originally Posted by HughJorgan View Post
    In researching it, using blue for maps was one of the other factoids I gathered. Here's one reference a quick google search comes up with; there are others:

    http://www.flashlightuniversity.com/...lors-and-uses/
    You appear to have made a very common error: mistaking a web search for "research". That site you just linked has this little gem: Blue light is the only light that can cut through fog, which is why it is widely used for fog headlights.

    Ummmmm...no, blue isn't the only light that can cut through fog, because because no it doesn't; there's no light that can "cut through fog". And no, blue is not used widely (or at all) for "fog headlights" (or any other legitimate vehicle lights except the flashing ones on police cars).

    Just because it's on the internet doesn't mean it's true -- not even if it's on a site claiming to be educational.

  13. #13

    Default Re: Red map light: good idea?

    I swapped out the cab lights in my big truck for red. I find it much more comfortable if the swamper needs too grab something while i am driving. Plus it looks cool.

    The peterbilt has a floodlight on each side as well as an aimable spotlamp. I swapped the floodlight out for red and left the spotlight clear so i have an untinted light for doing paperwork/logbooks.

  14. #14
    Moderator Alaric Darconville's Avatar
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    Default Re: Red map light: good idea?

    Quote Originally Posted by HughJorgan View Post
    Once upon a time I switched my car's map lights to red bulbs. I left it like that for years but really it wasn't a good idea. Reading maps or general purpose, it's just too hard to see details. Blue lights are recommended for nighttime reading of maps specifically, they don't impact your night vision as much while also don't wash out markings on the maps.
    If the map has any blue marking on it at all, they'll be invisible under blue.

    Blue is also a TERRIBLE light color if you intend to preserve your night vision.

  15. #15

    Default Re: Red map light: good idea?

    I would be reluctant to have only red cabin lighting in my vehicle. It seems to me that could make a police officer "hinky" if they stopped me after dark.

  16. #16

    Default Re: Red map light: good idea?

    I thought green had become the preferred low light color for reading paper maps as it doesn't make the red warning and danger markers disappear nor does it make it difficult to see bodies of water, two rather important things you need to see when using a map on a rally course or S&R run. Personally I'd rather just use a low intensity white light for map reading.

    That said, my 2001 VW Passat has a pair of red LEDs mounted in the rear view mirror pointing down to illuminate the console area for seeing the controls, it works fine. It also has red led back-lighting for all the window and lock controls.

  17. #17
    Flashaholic* zespectre's Avatar
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    Default Re: Red map light: good idea?

    so this got me curious. I had an amber LED handy so I pulled one of the red map lights and made it amber.
    well what do you know.... I like it

    I think I'm going to switch them both to amber (though I'm leaving the DOME lights alone.
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  18. #18

    Default Re: Red map light: good idea?

    We're days away from the year 2018. Are we really still trying to read paper maps in the car?

  19. #19

    Default Re: Red map light: good idea?

    Quote Originally Posted by -Virgil- View Post
    We're days away from the year 2018. Are we really still trying to read paper maps in the car?

    I'm not, nor was that the intention. But I do "store" random items on my passenger seat, and sometimes I need to locate one of them when it's dark.

    The dome light will remain cool blue/white, as will the driver side map light. Only the passenger side will be changed to red. If I don't like that, I'll try amber. They're cheap enough to play with.

  20. #20
    Flashaholic Bicycleflyer's Avatar
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    Default Re: Red map light: good idea?

    Quote Originally Posted by -Virgil- View Post
    We're days away from the year 2018. Are we really still trying to read paper maps in the car?
    Yes, I still carry paper maps. I even use them. Heck, I even have phone books and a city directory. Technology does fall short sometimes. My GPS does create goofy routes sometimes and my smart phone has failed to load data.

    As for the red light, I have flown airplanes that use a red flood light. In those instances I have had to use a flashlight at times to see what the red has washed out. VFR charts use a color called magenta, which is a reddish color. That washes out all the time. Truth is, most newer planes just use white light.

    Green is used by the military during NVG flights to prevent the red from glaring in the googles.

    As I understand it, red does not affect the eye’s acuity. Perhaps that is the reason it is used on gauges.

  21. #21
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    Default Re: Red map light: good idea?

    Moderator Edit
    Please reread the CPF Rules and FAQs, particularly rule #4.

    --Alaric D
    Last edited by Alaric Darconville; 12-18-2017 at 10:58 AM.

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    Flashaholic* Echo63's Avatar
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    Default Re: Red map light: good idea?

    Quote Originally Posted by -Virgil- View Post
    We're days away from the year 2018. Are we really still trying to read paper maps in the car?
    Paper maps, No.
    Road books using tulip diagrams, in conjunction with a trip meter - Yes.


    I am planning on modifying the wiring on my overhead "map lights" in my subaru, to give a very dim red when the passengers light is switched on, and a normal "warm white" in both sides when the drivers side switch is flipped.
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  23. #23

    Default Re: Red map light: good idea?

    Personally I think a dimmer "enough" light level works fine instead of red lighting. Sure it can affect your night vision but in a vehicle unless you are driving without headlights in the dark I don't think changing to red lighting would help vs dim white lighting as once you look at stuff with your white headlights you've already compromised whatever night vision you have anyway. I've had red and green lighting on my dash and I have mixed emotions about them both as I like both colors of lighting for different reasons in that red lighting is more relaxing than green which is both good and bad. Green lighting can help keep you awake if you are starting to get too tired than red which can relax you if you need to be relaxed but if relaxed too much you could nod off while driving. I don't really notice any difference in night vision driving with my headlights on between the two colors and when you have a huge contrast in the light in your vehicle and outdoors shining in either in a tunnel or when driving into the sun sometimes a brighter lit dash can be seen easier than dimmer (or red) color. I'm thinking one reason red is used by the military is less for night vision and more for remote detection that is when you run a red light the enemy cannot see it as well at a distance than white light and since pilots usually don't have strong enough "headlights" to see anything while in the air reflecting back on them having night vision is a great advantage.
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  24. #24

    Default Re: Red map light: good idea?

    Quote Originally Posted by Lynx_Arc View Post
    once you look at stuff with your white headlights you've already compromised whatever night vision you have anyway.
    Actually, night driving with headlamps (and roadside building/sign lights, street lights, etc) is in a visual mode called "mesopic". It has elements of "photopic" (bright light) and "scotopic" (dark) vision modes.

    red lighting is more relaxing than green
    Interesting claim. This is your personal opinion you're stating?

    Green lighting can help keep you awake if you are starting to get too tired
    {{{citation needed}}}

    red which can relax you if you need to be relaxed but if relaxed too much you could nod off while driving.
    {{{citation needed}}}

    I'm thinking one reason red is used by the military is less for night vision and more for remote detection that is when you run a red light the enemy cannot see it as well at a distance
    This sounds like a guess, right? Because {{{citation needed}}}.

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    Flashaholic* Daniel_sk's Avatar
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    Default Re: Red map light: good idea?

    It's very difficult to read ordinary maps under red light - that is because anything printed in red color will become almost invisible on paper under red light. I think the older military paper maps actually omitted red because of this, it's also difficult to distinguish colors (again - that's an issue with maps, when you have different trails marked with different colors). This is from my experience while night hiking and trying to use red light. I prefer low lumen warm white color for this use case.
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  26. #26

    Default Re: Red map light: good idea?

    Quote Originally Posted by -Virgil- View Post
    Actually, night driving with headlamps (and roadside building/sign lights, street lights, etc) is in a visual mode called "mesopic". It has elements of "photopic" (bright light) and "scotopic" (dark) vision modes.
    Out of town when headlights aren't hitting anything but at greater distances the light reflected back shouldn't affect night vision anywhere near as much as when you are in town driving.

    As for Red vs green being more relaxing it is sort of why people want warm white LEDs vs puke green tints the green tint is more irritating to some (including me).
    Finally here is an article that states Red is the least visible color at a distance.
    https://sciencing.com/visible-colors...e-8209029.html
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  27. #27

    Default Re: Red map light: good idea?

    I was rooting around in my coffee can of random light bulbs (doesn't everybody have one??) and I found a 5w incandescent in amber, so I gave it a shot. I rather like it, and will be ordering an LED version, hopefully none too bright.

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    Default Re: Red map light: good idea?


  29. #29
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    Default Re: Red map light: good idea?

    Quote Originally Posted by HKGuns View Post
    It is 100% fact. Subs rig for red before going to periscope depth for this reason. Pretty much a well established fact in the military circles.
    That doesn't mean that red is "better" for seeing or even necessarily for maintaining night vision. There is a lot of misinformation, misinterpretation, etc. about red-light and night vision.

    w.r.t. subs, while where is the concern about not waiting for night vision adaptation, it is also because light goes both ways in a periscope and you want to ensure the least visibility if light accidentally exits the periscope.

    If you truly want to maintain your night vision, you must use >660nm as indicated above. This is where the photochromatic step is. Anything less, and mainly you are just using a low effective amount of lumens.

    There are some other advantages of red including less glare at low lighting levels, and you have highest visual acuity in the red, if the target has high contrast in red. However, in many cases, and as a general rule, you would be equally served by a very low level of white light which guarantees contrast in far more situations and will still allow you to maintain a level of night vision suitable for driving.

    Who the heck uses paper maps any more though? :-)

  30. #30
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    Default Re: Red map light: good idea?

    I suspect there's a good reason why general aviation aircraft of numerous brands use red lighting for the instrument panel.
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