There has been much discussion of NVG (Night-Vision-Green 495-505nm) vs red light (1 2 3 4 5), some of it contradictory. Since all these discussions failed to un-confuse me, I decided to put it to the test myself. With comments such as "eyes most sensitive to NVG" and "more contrast/detail with NVG" I was ready to agree that NVG would be superior to red for dark-adapted eyes. Imagine my surprise when I found exactly the opposite!
I purchased an NVG Photon Freedom Micro and compared it's lowest setting with a dollar-store red keychain LED (two button alkalines). The wimpy dollar store LED has total fewer lumens so I really expected the NVG to win, but while the NVG light was "brighter" (even on the dimmest setting), I saw less contrast and less detail! I tried a variety of objects around the house including black text on white papter, and the dimmer red won out for sharpness and contrast every time. This was just after waking up in the morning before the sun came up so I should have had complete dark-adaptation.
I think I might understand what's going on here. From what I gather rods are the cells that see NVG in scotopic night vision, and since there are fewer rods in the eye, naturally resolution is lower. And since cones, which are much more numerous, see the red, acuity is higher.
Actually seeing things in the dark is a totally different matter than preserving night vision, and for for me in close distances around the house, red wins. If red has an added advantage over NVG when it comes to preserving night vision, for me that's merely a pleasant fringe benefit.
And as for destruction of night vision, neither NVG nor red noticeably damaged my dark adaptation at these low, low levels. So while my test is admittedly subjective and unscientific, I must concur with the conclusion that some have drawn, which is that what really matters to preserving night vision is using very low levels...of any color.
I purchased an NVG Photon Freedom Micro and compared it's lowest setting with a dollar-store red keychain LED (two button alkalines). The wimpy dollar store LED has total fewer lumens so I really expected the NVG to win, but while the NVG light was "brighter" (even on the dimmest setting), I saw less contrast and less detail! I tried a variety of objects around the house including black text on white papter, and the dimmer red won out for sharpness and contrast every time. This was just after waking up in the morning before the sun came up so I should have had complete dark-adaptation.
I think I might understand what's going on here. From what I gather rods are the cells that see NVG in scotopic night vision, and since there are fewer rods in the eye, naturally resolution is lower. And since cones, which are much more numerous, see the red, acuity is higher.
Actually seeing things in the dark is a totally different matter than preserving night vision, and for for me in close distances around the house, red wins. If red has an added advantage over NVG when it comes to preserving night vision, for me that's merely a pleasant fringe benefit.
And as for destruction of night vision, neither NVG nor red noticeably damaged my dark adaptation at these low, low levels. So while my test is admittedly subjective and unscientific, I must concur with the conclusion that some have drawn, which is that what really matters to preserving night vision is using very low levels...of any color.