Good topic, George. I'm afraid Father Time is nibbling at my night vision so this is something I'm familiar with. When I do have to turn on a white (or green -- good suggestion!) light, I usually close one eye so the night vision is diminished in only one eye, and I can still use the other if I need dark-adapted vision for something in the next 30 minutes or so. Thanks for the video!
Red light or color itself impacts cone cells. Humans are trichromats meaning we have 3 types of cones red, blue, green, rod cells on the other hand detect light itself and not color wavelength. Night vision is dependent on a particular photo pigment on the rod cell called Rhodopsin. Exposure of white light light immediately photobleaches the rhodopsin on those rods which is what causes that night time blindness which no one at a star party wants to have happen. In the absence of that light rhodopsin regenerates in about 30 minutes or so. Light emitted in the red wavelength has the least ability to photo bleach that rhodopsin which is why it’s highly desired as a night vision sparing light. Moving down the wavelength towards the blue end of the spectrum increases the lights impact on rhodopsin so going from red to yellow to green to blue is going from most NV sparing to least, white light is a combination of all the colors so regardless of the presence of the red light the other wavelength bleaches the rhodopsin out. The human eye is most sensitive to green light in terms of what pops the most for us… Green light at a wavelength of 555nm. Of the visible spectrum that we can see. Red light has the least energy per photon while blue has the highest. If you can get away with red light that’s fantastic if you need more than moving to orange would be next ideal followed by yellow followed by green… unfortunately I have not seen headlamps with yellow or orange leds since these colors are either a mix of primary colors or specially designed leds which output a single wavelength.
A follow up to what I wrote. If you can get a flashlight and stick an amber filter on it that would be better than a green headlamp then again it wouldn’t be a headlamp. Also you would have to make absolutely sure there would be zero light leak around the filter. You could combine wax paper with the filter to further diffuse the light if it’s too intense although in the desired wavelength
And it’s rod cells which are responsible for human biological night vision not cones. However the red light that we see photobleaches rhodopsin the least that’s why we use red light for night vision illumination. The human eye is more sensitive to green wavelengths (explains your statement starting at 3:30) which is the premise for using it if you can’t get enough from red light. Although this does come at the cost of more rhodopsin bleaching than red however not as much as full spectrum light aka white light. As for hunting and green light that is because most non human mammals are dichromats meaning they are red green color blind and they see the world in terms of blues and yellows. Dichromats don’t see red like we do and barely see green instead being more grayish to them. Red is the ultimate light for hunting and night vision because number one it bleaches the rhodopsin in our rods the least and is furthest away from what dichromat animals can see. Green because we are most sensitive to that wavelength will see objects brighter than red or blue light alone. White is the ultimate for illumination because it includes all wavelengths and is thus the worst for night vision. Yay for us astronomers lol
I use a $200 blackdiamond distance 1500 headlamp that does 300/600/900/1500 lumens but then again I do nighttime backcountry snowshoeing. When I’m using my telescope I’m using the red auxiliary led for night vision don’t want to melt my telescope with a headlamp that can output light rivaling a cars headlamp.
I tape a piece of paper or that low tack blue tape over most of my lights, it makes a glow instead of a harsh light in any mode. Those red/ green lights are sold as 'tracking' lights for hunters. (Doesn't work well for that, lol)
Good topic, George. I'm afraid Father Time is nibbling at my night vision so this is something I'm familiar with. When I do have to turn on a white (or green -- good suggestion!) light, I usually close one eye so the night vision is diminished in only one eye, and I can still use the other if I need dark-adapted vision for something in the next 30 minutes or so. Thanks for the video!
Red light or color itself impacts cone cells. Humans are trichromats meaning we have 3 types of cones red, blue, green, rod cells on the other hand detect light itself and not color wavelength. Night vision is dependent on a particular photo pigment on the rod cell called Rhodopsin. Exposure of white light light immediately photobleaches the rhodopsin on those rods which is what causes that night time blindness which no one at a star party wants to have happen. In the absence of that light rhodopsin regenerates in about 30 minutes or so. Light emitted in the red wavelength has the least ability to photo bleach that rhodopsin which is why it’s highly desired as a night vision sparing light. Moving down the wavelength towards the blue end of the spectrum increases the lights impact on rhodopsin so going from red to yellow to green to blue is going from most NV sparing to least, white light is a combination of all the colors so regardless of the presence of the red light the other wavelength bleaches the rhodopsin out. The human eye is most sensitive to green light in terms of what pops the most for us… Green light at a wavelength of 555nm. Of the visible spectrum that we can see. Red light has the least energy per photon while blue has the highest. If you can get away with red light that’s fantastic if you need more than moving to orange would be next ideal followed by yellow followed by green… unfortunately I have not seen headlamps with yellow or orange leds since these colors are either a mix of primary colors or specially designed leds which output a single wavelength.
A follow up to what I wrote. If you can get a flashlight and stick an amber filter on it that would be better than a green headlamp then again it wouldn’t be a headlamp. Also you would have to make absolutely sure there would be zero light leak around the filter. You could combine wax paper with the filter to further diffuse the light if it’s too intense although in the desired wavelength
Hi George - nice video and it’s the cones that are responsible for the color vision. ;-)
Thank you. I knew someone would have what I forgot.
And it’s rod cells which are responsible for human biological night vision not cones. However the red light that we see photobleaches rhodopsin the least that’s why we use red light for night vision illumination. The human eye is more sensitive to green wavelengths (explains your statement starting at 3:30) which is the premise for using it if you can’t get enough from red light. Although this does come at the cost of more rhodopsin bleaching than red however not as much as full spectrum light aka white light. As for hunting and green light that is because most non human mammals are dichromats meaning they are red green color blind and they see the world in terms of blues and yellows. Dichromats don’t see red like we do and barely see green instead being more grayish to them. Red is the ultimate light for hunting and night vision because number one it bleaches the rhodopsin in our rods the least and is furthest away from what dichromat animals can see. Green because we are most sensitive to that wavelength will see objects brighter than red or blue light alone. White is the ultimate for illumination because it includes all wavelengths and is thus the worst for night vision. Yay for us astronomers lol
I use a $200 blackdiamond distance 1500 headlamp that does 300/600/900/1500 lumens but then again I do nighttime backcountry snowshoeing. When I’m using my telescope I’m using the red auxiliary led for night vision don’t want to melt my telescope with a headlamp that can output light rivaling a cars headlamp.
I tape a piece of paper or that low tack blue tape over most of my lights, it makes a glow instead of a harsh light in any mode. Those red/ green lights are sold as 'tracking' lights for hunters. (Doesn't work well for that, lol)
I have tape over all of my equipment lights. They are too bright.