What colour light source should I use to preserve my night vision?
A. Firstly, we are referring to the colour of the actual light source, not light that has passed through a coloured lens. Secondly our night vision capability can vary depending on the amount of sunlight we have been exposed to. I found one study of pilots that found that a full day in the sun significantly affected night vision and ten consecutive days of sunlight exposure reduced visual acuity, visibility range and contrast discrimination by half. Red is the best light for preserving night vision provided you only use the lowest light level needed. However, if you are reading a map, then a red light will cause the red lines to disappear so a low level green light would be best. Green is often favoured by hunters as apparently animals cannot see or are not bothered by a green light. Some people assume green is preferable for night vision, referring to the green displays used in military night vision equipment. The display colour in these equipments has nothing to do with preserving ni
