Single point Scope Red Dot OEG (Occluded Eye Gunsight)
Singlepoint’s moment of fame came during the Vietnam War when it was used by U.S. troops in the Son Tay prison camp raid in 1970. Arguably, the success of Singlepoint gave rise to the popularity of a somewhat similar Armson OEG that is still made today, the rise of Trijicon’s Bindon Aiming Concept (BAC), and the enormous variety of red-dot sights that have largely replaced OEGs in common use.
Unlike modern red-dot optics, the Singlepoint OEG is just a sight — there are no optics involved. It is also unpowered. The end of the fiber optic can be seen beneath the clear plastic dome at the business end. Light is gathered there, and the center of the sight glows in the color of the fiber-optic filament, which is much larger than we are currently accustomed to. The dot is a whooping 16 MOA, which is massive compared to what we encounter today. To facilitate use at night, a small vial of tritium was located near the light-gathering hole at the front of the OEG to make the fiber-optic filament glow. This would mean the dot would appear green during nighttime hours.
The OEG concept takes advantage of the peculiarities of our binocular vision. A human brain takes image data from both eyes and seamlessly superimposes it. Generally, most of it comes from our dominant eye, with the other eye providing some additional detail and field of view.
An OEG tricks our vision into doing something a little different. Occluded means “blocked” or “obstructed.” You cannot see through an OEG. All it does is project a bright aiming point to your dominant eye that looks like it is fairly far away so your eye can still be focused on a distant object.
However, if both of your eyes are open and your other eye is focused on the target, the brain will superimpose the bright red dot from the dominant eye onto the image of the target from the nondominant eye. The important thing is to not try to focus on the dot. This method works for high-speed engagements where you keep your focus on the target. If you try to focus on the dot, it all falls apart.
OEGs do not work for everyone. Some people do not have very good binocular vision (many are born that way, and others have had some sort of an eye injury). This also does not work for people who are cross-eye dominant (i.e., right-handed with left-eye dominance) if they shoot with the dominant side.
There are other problems with OEGs. The first one is parallax. It’s due to the distance between the eyes, so there is an offset between the point of aim and the point of impact. Another is that the sight-in is individual. An occluded sight setup for one person is unlikely to be properly sighted in for another.
Aside from these issues, OEGs are extremely fast and work great for center-mass hits at close range. For me, 25 to 30 yards are the practical limit for reasonably accurate OEG use, but I know of people who are successful with them out to around 100 yards.