27 Jun Village Praxis: Unaided Night Vision by Bill Buppert
Publisher’s Note: Day after day, one who pays attention knows that the imperial mandarins in Mordor on the Potomac have zero goodwill toward their charges in the zoo they have created in the USSA. The politicos and apparatchiks take their exsanguination program of the Helot in their pet vampire nation most seriously. The game is afoot and it is just a matter of time before the real unpleasantness starts with the descending Endarkenment sponsored by the Orcs in power. There is no cavalry on the horizon, you are on your own.
On occasion, we will publish arcane or neglected lore and this happens to be one of them. I would urge you to give this a try. This would synchronize nicely with some the other forgotten skills like navigating with no tools other than you organic optics and intellect Harold Gatty died in the 1950s but his guide is quite useful. He studied the earlier cultures such as the Vikings, Polynesians, Portuguese, Native Americans and Aborigines to divine their wandering ways. I highly recommend it. The methods covered range from the usual — such as stars, the sun and trees — to less common ones such as the routes of migratory sea birds or seasonal winds. As a matter of fact, find an active outdoorsman over the age of fifty in your neck of the woods and start an informal apprenticeship under him.
The same applies to the following short overview of unaided night vision. Do you happen to know a fellow shooter at the range who just happens to be an optometrist or ophthalmologist? Ask around. Then explore some of these questions with an expert. These kind of interdisciplinary investigations is what opens new answers to unresolved questions.
Our first Village Praxis entry was July 2009. My, how time flies. -BB
While modern Western armed forces have sophisticated technologies and methodologies to increase visual acuity at night, one should practice what’s available when technology fails. Not everyone can afford to shell out three thousand dollars for their personal Third Generation night vision devices. Unaided night vision and “dark adaptation” is a compromise in the following components:
- The inability to distinguish colors.
- No detail can be seen (about the same as 20/200 vision in daylight).
- That nothing can be seen directly in front of the eyes (no rods in the center of the retina), you must learn to look about 15-20° off center.
- Only motion can be detected well, therefore you may have to learn to move your eyes to detect something that doesn’t move.
- Objects that aren’t moving appear to move (autokinesis). This has probably led to a number of plane crashes.
It takes the average person 30-45 minutes to acclimate to total night vision capability unaided. The ability to ruin carefully nurtured night vision for an event can quite literally be disposed of in a flash.
Bottom line is that apart from studying the mechanics of your eyes, the primary two means are:
Diamond viewing: “It is similar to the off-center vision technique taught in rifle marksmanship. Diamond viewing means that you move your eyes just slightly, a few degrees, in a diamond pattern around the object you wish to see. You do not have to move your head-use your peripheral vision.”
Looking around objects. Your eyes are much more effective at the periphery of the cone than the center in low light conditions and movement can be detected with more alacrity.
There are a number of resources for TTP on these variations of unaided night vision.
FM 3-21.94 Appendix B, Limited Visibility Operations.
An unaided night vision instructional program.
This training presentation gives a great overview fro team training on unaided night vision.
The bottom line is you have to reduce the recovery time back to night vision (dark adapted or scotopic).
This extract from FM 3-22.9 Rifle Marksmanship M16-/M4 Appendix H describes the following in its appendix:
- NORMAL BLIND SPOTS – The normal blind spot is always present, day and night. It is caused by the lack of light receptors where the optic nerve inserts into the back of the eye. The normal blind spot occurs when you use just one eye. When you close the other eye, objects 12 to 15 degrees away from where you are looking will disappear. When you uncover your eye, the objects will reappear.
- NIGHT BLIND SPOTS AND VIEWING TECHNIQUES – When you stare at an object under starlight or lower levels of illumination, it can disappear or fade away. This is a result of the night blind spot. The night blind spot affects both eyes at the same time and occurs when using the central vision of both eyes. Consequently, when looking directly at an object, Soldiers miss larger objects as the distances increase. A hand grenade 2 meters away might not be seen; an enemy Soldier at 50 meters may be missed. An M1 tank at 300 meters can even be missed.
- AVOIDING NIGHT BLIND SPOTS – To avoid night blind spots–
• Look to all sides of objects you are trying to find or follow.
• DO NOT STARE.
**Diamond viewing, a technique similar to the off-center vision technique taught in rifle marksmanship, is a good technique for peripheral viewing. To use the diamond viewing technique–
• Move your eyes just slightly, a few degrees, in a diamond pattern around the object you wish to see.
• Do not move your head; use your peripheral vision.
- DARK ADAPTATION – In order for your visual system to work efficiently at night, you need to dark-adapt, or get your eyes used to seeing things under low light conditions. Dark adaptation is similar to walking into a movie theater when it’s very dark; you can’t see things at first, but as your eyes gradually adapt, you can see better. “It takes about 30 to 45 minutes to fully dark-adapt when going from a brightly lighted area into the dark. However, people dark-adapt at varying rates. People who are older, people who smoke, or people who are not in great physical shape will take longer to dark-adapt. There are three stages of dark adaptation:
• Daylight vision.
• Twilight vision.
• Night vision.
- Daylight Vision – Daylight vision occurs under maximum lighting conditions, such as when the sun is shining or in a well-lit room. Under these conditions, Soldiers have–
• Optimal visual acuity. In daylight conditions, Soldiers use both their central and peripheral vision, which provides optimal visual acuity—20/10, 20/15, and 20/20 vision.
• Optimal color vision. Colors look most vivid under daylight conditions.
• Quickest reaction time.
- Twilight Vision – Twilight vision occurs during many military night operations and when driving around in a car at night. It occurs at dawn and dusk, down to full moonlight; when there is artificial illumination; and when snow is on the ground at night. It can occur in the daytime with several layers of jungle canopy. Under these conditions, Soldiers have–
• Poorer visual acuity. Visual acuity can be as poor as 20/100. Under twilight conditions, optimal visual acuity is between 20/50 and 20/100.
• Poorer color vision. Colors will not be as vivid.
• Slower reaction times.
- Night Vision – Night vision occurs under starlight, as well as on moonless and cloudy nights when there are no stars or cultural lighting. Remember, there is a night blind spot, as discussed earlier. Under these conditions, Soldiers have–
• The worst visual acuity—from 20/200 to 20/400 and possibly much worse. Soldiers can recognize silhouettes, but not details of the objects. This is why knowing the silhouettes of vehicles and critical natural and man-made objects is
• Poor color vision. Soldiers cannot see colors, only various shades of gray. The longer wavelengths of light, such as the reds and oranges, are hard to see and appear dark. Unless a dark color is bordered by two lighter colors, it becomes totally invisible. On the other hand, greens and blues appear brighter, but Soldiers may not be able to determine their color. Note: Reds are almost invisible at night. Red crosses are on white backgrounds on tents or vehicles so they can be seen more easily at night.
- PROTECTING (BEFORE OPERATION) – Soldiers must protect their eyes before night operations so they can dark-adapt in an efficient manner. To efficiently dark-adapt, use the following suggestions:
• Don’t smoke before night operations. Not smoking four to six hours before night operations will aid in dark adaptation.
• Wear sunglasses if you plan to spend time in the sun. Without sunglasses, it will take longer to dark-adapt.
• Watch what you eat. Maintain adequate levels of Vitamin A.
• Use dim white lighting or red lighting before night operations.
PROTECTING (DURING OPERATION) – Once a Soldier has dark-adapted, it is important to maintain that dark adaptation. To maintain dark adaptation, use the following suggestions:
• Minimize your use of unnecessary lighting.
• Close one eye before being flashed by flares and other bright lights.
- ILLUSION (APPARENT MOVEMENT OF LIGHT) – The illusion of movement, which a static light exhibits when stared at in the dark, is related to the loss of surrounding visual references that normally serve to stabilize visual perceptions. Consequently, very small eye movements are perceived by the brain as movement of the light. To avoid illusions of movement–
• Begin a scan pattern, and control the eye movement.
• Use large movements, and scan.
• Try to find another light, and shift your gaze back and forth between the lights.
All of these techniques demand tailoring and customizing to the needs of yourself and those you train with.
I do wish I could recommend further reading but there is nothing I have found that is useful. Some gun writers with zero optometry nor ophthalmic knowledge have put out some things I would stay away from. There is a real need for a trained eye science professional to address this from a brass tacks perspective for low/no light application for unaided night vision.
Read. Train. Resist.