Purpose of coloured lights on head torches

[wayno]

some head torches now come with multiple coloured lights,
originally it was just red for low light conditions, but you can now get them also with blue and green on the same head torch
I havent found information that explains the best use of these lights.
the green is the brightest of the colours, the blue the next brightest with the red the dimmest
i'd red green and blue were better than red to reduce night blindness, but the green is a lot brighter, its arguably too bright even for a night light in a hut...
blue isnt too bright, but in theory that can interupt or prolong your body clock letting you get to sleep...
that brings you back to.... red...
maybe i'd use blue or green when i wake up and red before going to sleep or in the middle of the night...
Yeah... first world problems... terrible arent they....

[Mark F]

Red allows animals to be observed without spooking them as many animals cannot detect red light. Useful for checking on marauding possums etc in the dead of night.

[johnw]

Red allows animals to be observed without spooking them as many animals cannot detect red light. Useful for checking on marauding possums etc in the dead of night.

I've found red also stops you blinding your companions in camp and helps preserve night vision.
I generally use red most of the time for cooking etc and in the tent, unless I can't find something.
Or need to go for a walk in the bush to find the bathroom. Or on a very rare night walk.
As for the other colours, I don't know. But I'll bet someone will have researched it.

[CraigVIC]

Sales person told me blue was for following blood trails. I enquired no futher.

[Heremeahappy1]

Old army angle torches came with multiple colour filters too. Red always preserves your night vision, makes sense. Not sure about the rest. Maybe to read features on a map??
I prefer three options in a headtorch red, dim white and brighter white... and has a lock out to prevent unintentional battery drain.

[FatCanyoner]

Yeah, I remember red and green filters on my old army torch too. I don't recall using the green -- only the red -- so don't think I ever learnt the purpose.

[GBW]

From Google so it must be true...The color green is the most visible and sensitive color to the human eye. Green lighting was introduced into operating rooms in 1914 by Dr. Harry Sherman who found the color green reduces glare and complements hemoglobin red, the color of blood, to create a more visible environment for surgeons.

Yellow lights commonly used in fog

[wayno]

Sales person told me blue was for following blood trails. I enquired no futher.

I'll never be able to look at someone with a green torch the same way ever again....

[Huntsman247]

https://www.flashlightuniversity.com/le ... -and-uses/

[Neo]

Green filtered light doesn't upset a plants daylight rhythm, ie wont wake it up or trigger a season change (day length).

Red to not upset your night vision/eyes adjusted to the dark. Also other animals not noticing the red lighting.

[rcaffin]

Multiple colours gives the Marketing Dept something extra to bleat about.
I find the red useless. I have not tested the other colours.

Cheers
Roger

[wayno]

Multiple colours gives the Marketing Dept something extra to bleat about.
I find the red useless. I have not tested the other colours.

Cheers
Roger

red isnt as effective at reducing night blindness as is made out, it does actually activate your day vision. but when you turn it on in a hut bunk room at night its less likely to start a fight than a white light torch...

[Tortoise]

... but when you turn it on in a hut bunk room at night its less likely to start a fight than a white light torch...

Yep. And give those early risers the red option! Not that I hut much these days.

[matagi]

The red light is also useful when sharing a tent. Avoids having a disgruntled spouse.

[Lamont]

We are talking biology of the eye, especially the Retina and it's role in sight for both; colour perception and visual acuity or detail (and the Pupil for red light) and the retina's light receptors called photoreceptors -named Rods and Cones. No rods and no cones functioning =you don't 'see' i.e. you don't perceive colour and detail.
Rods are used (stimulated) in low light and give a rough shape but no colour. Cones are used for colour perception and visual acuity used (stimulated) most in white light-which is made up of ROYGBIV, Red, Orange etc-the Visible Light Spectrum-for humans.
Red light allows your pupils to remain quite large (not full dilation though-so you aren't blinded by your companions red light) ..similar to the biological pupil reflex to darkness- but the advantage is you will have light and so see far better in near dark. With the Red light you're engaging both rods and cones on the retina with the red light rather than just rods (rods are used in darkness-pupil fully dilated-no colour discernment) so you wont see a vague non coloured image (you still wont likely see much colour-just shades) but you'll have some some visual acuity (cones-are used for fine detail and colour and used in full white light-ROYGBIV) as well ie detail. Apparently animals that are colour blind can't see the red light as well. Hunters stalking?
Green being a different length wave on the visible light spectrum and right in the middle ROYGBIV allows most detail to be discerned from memory because it triggers a wide range of cones (not just green but some cones either side) that receive light and that we perceive as a wide range of colours ie. so we get the 'best' range of colour discernment in low light and should be best depth of vision also.
Blue I think is added because as Craig said it 'reacts' with bodily fluids (not the best though) and allows you to discern them-hunters again I suppose.
I have seen all sorts of coloured filters on different coloured lights -it looks like these are thought to give a person a good smattering of choices (selling point for the hunter/bushwalker) for most circumstances.

Last edited by Lamont on Sat 19 Dec, 2020 9:31 am, edited 3 times in total.

[wayno]

thanks very much for the elaboration,, explains it nicely...