Night vision

If my memory serves my correctly, did not the findings of the Ouzo Tragedy include comments about the watch keepers night vision being seriously impaired by the white lights behind him on the bridge and the passenger deck which were not properly excluded from his position and his night vision taking 15 to 20 minutes to get back to about 50% if he managed to get somewhere dark?
 
the intensity, not the colour, of the light you use to read your chart is what knackers your night vision.

i did a search through the medical literaturea few years ago. i found one paper (in the '50's?) that suggested that red light may be slightly better, but that the main issue is intensity, not colour

no one has mentioned "shut one eye" i find it v helpful for seeing a chart with a headtorch, then returning to cockpit with full night vision in t'other eye

had a shot of some RAF NVG last month - they were very good, but i don't have the £ spare...
 
I am so glad to hear this. I very quickly found that using red light was useless and have used a white light since. I just thought that it was me being abnormal....but now I find I AM NORMAL :-).......I think?

Gerry www.sadler32forsale.com
 
It takes about 40 mins to acquire full night vision since this is a chemical change, though much of it happens in the first minutes. If you can keep the chart work as short as practicable this will lessen the amount of adaptation lost.
 
bikedaft said:
the intensity, not the colour, of the light you use to read your chart is what knackers your night vision.

i did a search through the medical literaturea few years ago. i found one paper (in the '50's?) that suggested that red light may be slightly better, but that the main issue is intensity, not colour
...
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I am inclined to agree about intensity. Going below i do not look directly at the light source. I do not think my cabin lights are that bright. As i said in my opening thread if my crew shines the torch in my face or even reflects light off the white cabin bulkhead then i do loose night vision.
I do not think it takes 20 mins to get it back.
I do think red is useless for reading.
My instruments have a mixture of green & red & green is softer on the eyes
My instrument lights are on the deck hatch so are not " in my face" as with say a chart plotter on a steering binnacle so the light does not worry me much
My eyes are blue & possibly react to a different colour spectrum. Ie I hate sunglasses with brown lenses but like blue
I expect people with bown eyes react differently to the colours that suit me
 
If you can read detail when using white light it will take 15-30 mins before you obtain full night vision.
This is just physiology. There is nothing you do to change this (in the eye exposed). It is not effected by eye colour.

Full night vision is not always required, so dull white light can retain sufficient night vision for many situations but it its important to realise that this is less than full dark adaptation.

Once exposed to white light of sufficient intensity to read, full dark adaptation is a slow process.
 
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Dark adaption has nothing, or at least very little, to do with iris colour, colour vision, or. sunglass preference.
 
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Daydream believer said:
Possibly but i definitely react differently to different colours even compared to my wife who has brown eyes ( i think!!!)
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The colour of the eyes has nothing to do with the perception of colour, although some pigments are more likely to get damaged by UV. Colour perception takes place in the brain, and as far as I am aware nobody is sure that any two people perceive colours in the same way.
 
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