A recent conversation here about emergency lighting that led (excusethe pun) to head torches and the mention of red lights to helppreserve night vision when needed.An example of that was we were walking the dog last night with the Mrsand daughter and because the Mr's night sight seems to be pretty sh1tand so she generally carries a small pocket torch.Thinking it was helping us (walking in front) she shone her torchforward and because only daughter and I were keeping an eye on thedog, we would often be turning round and ending up with a face full ofbright white light, then we could see less when we were lookingforward again.I believe red light is used to help lessen the impact of night visionloss but does it matter how the red light is formed?Eg, Years ago I made up a sun visor for my Messerschmitt with somegreen film that was used in stage lighting. The first set of trafficlights I came to I thought were out so had to double take under thevisor and seen they were indeed set to red. ;-(So, if I wanted to say manage her torch to make it less of an issue tous, would *any* red filter (within reason), or a red LED work re that?Cheers, T i m

It is more important to keep the light intensity low. Bright red light will kill your night vision just as effectively as bright white light. Red is traditionally used because a dim red light is better for keeping night vision than dim white light. However, for map reading at night, dim green or blue green may be better, as it allows you to see different colours better.

Lights colours and human night vision?

Nov 11, 2020 Last reply: 5 years ago 49 Replies

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T i m 5 years ago

Sure. I bought some battery / LED 'lanterns' and tried to use one to see stuff (picture holding it up in front of you like someone trying to walk in a storm with a 'storm lantern') and all it did was dazzle me. That's why many lanterns have a shield or reflector, masking some of the light radiation so it gives you a dark bit to help you not get a face full when using it like that. Had I not been in a hurry I would have just put it on a shelf or some such behind / beside me.

Sorry that should be the case Brian.

Yes, so it seems, if I turn the red work light down on my BIGLarry2 torch when walking outside at night it seems to impact my night vision less when I get more light back from reflections etc (which sorta makes sense).

Cheers, T i m

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polygonum_on_google 5 years ago

My usual torch was chosen as it has a relatively good CRI - fairly natural looking. I have found that I can use it effectively at very low settings such that it is (overall) much less bright than some other torches. But I see better with it.

By being less bright, it has less impact on night vision.

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Tim Lamb 5 years ago

Can country night time visitors using impossibly bright LED torches kindly not shine them at the face of the person who owns the land?

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whisky-dave 5 years ago

Cats have far better night vision.

Think of all the cats buried in the centres of our roads and motorways just so you know which side of the road you should be on ;-)

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T i m 5 years ago

Than ... not owls. ;-)

And there may be more spare if it's proven cats do carry Covid between people. ;-(

Cheers, T i m

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polygonum_on_google 5 years ago

You should wear a mask based on a retroreflector. That would show them.

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Dave Liquorice 5 years ago

That's deliberate, so you can't see their mates nicking your quad bike. B-(

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Dave Liquorice 5 years ago

On a clear moonless night I can get out of the car, straight after driving, look up and see the milky way. I don't think I have particulary good night vision, is finding just starlight enough to to move about safely unusual? I think finding the Milky Way "just there" is down to living in place with some of the darkest skies in England.

Shame about the cloud, rain, near gale and wind chill down to -5 C (air temp is a warm 8 C). B-)

Once my night visio has kicked in on a clear and moonless there are just some many visible stars that I can't pick out the constelations. Being short sighted, I just take my glasses off then I can only see the brightest stars which generally make up the constealtions. B-)

Depends how clear the air is, the milky wasy disappears somewhere between around 1/4 moon.

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Tim Lamb 5 years ago

Indeed:-)

Actually I don't have one. The land here is all reachable by public paths and I wear out a pair of cheap wellies each year!

On the last occasion, I suspect it was three youths out for a surreptitious smoke.

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T i m 5 years ago

<snip>

Can only have been 'country lads' Tim [1], 'urban yout' [2] seem to smoke anywhere, judging by how often I smell it as I walk about.

Cheers, T i m

[1] Unless they were under 10 possibly. [2] Or the 30 year old 'working from home' account manager neighbour who, from the regularity of the instances I smell when out in the back garden, must have longer smoke breaks than periods of 'work'!

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