Seeing in the dark

[Ollie]

What's the best way to keep your night vision when walking at night, but still having enough light to see that path below you?

Does anyone have any tips on how to heighten your night vision? To make it more sensitive as it were?

Ollie

[David]

I have been told that a red light is less disruptive to night vision, apparently this is what the army use to read maps at night time (I don't know how true this is though)

To regain night vision just close your eyes for a while; in terms of permanently improveing it, I guess eating your carrots (or other veg!) is the only way.

[Marmot]

its the vitmamin A in carrots and some vegetables which causes an improvemnt in night vision. as vitmain a is needed for the regeneration of rhodopsin, the pigment in the rods of the eye which are responsible for being able to see in low light conditions.

Red light has always been more common as a preference to white light in order to retain night vision. However there has bee a move recently to the use of green light. The human eye is more sensitive to green light, so we can have better visual acuity in low light levels then red. Green also allows for better differentiating between colours then red - contour lines are especially more difficult using a red light then a green.

However, because of our sensitivity to gren light a strong green light is hugely more detrimental to our eyes then a red light of an equivilent strength .

Basically you only want a light strong enough to allow you to do your job, no more.

An interesting point of note is that it is belived that pirates are pictured as wearing eye patches not because they constatly lose eyes in fights but because wearing an eye patch will allow that eye to adjust to low light levels, the eye patch can then be removed when it starts getting dark and you then have an already adjusted eye to low light levels.

It is sensible when navigating a night that only one person looks at the map with the use of a torch - whilst the others do not crowd around and lose their night vision too - and the map reader could sensibly shut one eye before turning on the torch, thus retaining night vision in that eye

[Ollie]

An interesting point of note is that it is belived that pirates are pictured as wearing eye patches not because they constatly lose eyes in fights but because wearing an eye patch will allow that eye to adjust to low light levels, the eye patch can then be removed when it starts getting dark and you then have an already adjusted eye to low light levels.

Now that is an interesting fact! Very clever. I think I might look a bit silly walking round with an eye patch on though! :D

[David]

I have to agree with marmot about the colour differentiation problems; somethimes I have to use non-red light to tell the difference between two coloured areas, like blue in a lake. I guess this would be even more important for the army, for minefields and such marked in red!

[Ollie]

Was reading around on wikipedia the other day and came across this, quite a nice little read:

http://en.wikipedia.org/wiki/Night_vision

Amazing technology we have nowadays, eh?

[timmygowalkies]

Hmmm, interesting. Not something I really know much about.

My usual tactics are: once in the dark close eyes for 8-10 seconds then open and you can see :) that get's rid of the glare of lights in your eyes i.e when you come of a brightly lit road or a car with headlights on drives past you.

Red light takes away contour lines on the map, which can make it incredibly confusing if you are using the contours to navigate.

[Jake D]

And there was me thinking you just had to eat a lot of carrots :rolleyes:

[Shaggysheep]

I can remeber as a child being able to buy a torch that had different coloured glass that you could put over the ends to change the colur of the beam. Is it worth a try of putting the coloured paper you get on sweet wrappers over a torch end to lower the brightness of the beam. Hmm come to think of it I must get the youngsters try it to see how good it works.

[Ollie]

I work in lighting occasionally so I've tried all kinds of things - funnily enough coloured gels (the filters they put in stage lights) work quite well :D

They can stand quite high temperatures too. Lol.

Ollie

[timmygowalkies]

Yeh, I've thought about using them before, but I've never tried it.

Do you do any stage/theatrical lighting? I'm just starting to take over from a 6th former who leaves at the end of the year. I'll be doing the lighting for school drama competitions, music competitions and the school plays.

[Ollie]

Exactly what I do :) I'm also a mobile DJ amongst other hidden talents. :)

[TresMon]

Greetings from the new guy.
Neat posts. Military maps, at least the ones we had in the US Marine Corps are printed with a special ink that does show up under red filtered light. The problem is that on conventional maps, the blue (water) markings disappear or appear black in red light. On military maps blue appears as a distinguishable brown when illuminated in red light.

It takes a full 45 minutes for your eyes to get as much natural acclimation to the dark as they are able to. Just one tiny burst of white light kills your natural night vison and takes 45 more miuntes to max out. This is due to the arrangements of the rods & cones in the eye, or so I was told.

Lastly, we learned in close quarters battle to never look directly at what you want to see in darkness. Rather look just off to the side, but observe the object in the edge of your vison, that is in your periphrial vision. If seems odd at first but you will quickly note a little more detail to the viewed object. This technique is only good when you are not using artifical light (a torch) of any kind. It works though. Next night hike you go on center your vision just off to the edge of the trail. But view what is in the edge of your vision- the trail. You will trip over 90% less rocks, roots and such. This technique works to a noticable degree in moon & stralight. If your in the depths of the earth where their is ZERO natural light, fur-git-it. It is not magic.

I NEVER use white light unless it is an emergency. Even when a torch is needed in my home or around the cottage. Check out Petzl's head torch: "TakTikka." it has a red flip down lens. ;{