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Monday, July 5, 2010

A moldy oldie review: The Singlepoint sight



"I don't know just what it is, but I'll let you have it cheap." So said the fellow at the gun show, and that is how I came to have this thing in my collection. The Singlepoint is an ancestor of today's red dot sights. It created a stir back in the seventies. It was discussed in the English Parliament. Its moment of fame came on the Son Tay raid in the Vietnam war. It even got writeups in Popular Mechanics and Popular Science, honors reserved for things that were maximally cool.

By modern standards, though, it's a pathetic gunsight. It was a good try for its time, no doubt. It is an occluded eye gunsight (OEG), meaning you can't see through it. When you look in the end you see a black field with a red dot floating in it. You look at the target with your other eye and your brain merges the two images into one. Thus, you see the red dot superimposed upon the target.

Well, sort of. It doesn't work perfectly. The effects of phoria make the dot wander off the target if you aim for any length of time. Obviously this makes slow deliberate aiming impossible. You must shoot quickly or not at all.

Another problem with this sight is the dot is a whopping 16 MOA across. That is much too big--bigger than many targets I'd want to aim at. I find it necessary to sight in so that my point of aim is at the top center of the dot, right at the 12 o'clock position. I then use the dot as if it were a bead sight, placing the target atop it to aim.

Despite its peculiarities, the Singlepoint was successful in getting riflemen interested in the red dot idea. Improved dot sights that you could actually see through were soon on the way. A sight tube you could look through eliminated phoria effects by giving both eyes a shared view of the target.

One problem the Singlepoint's design solved brilliantly was that of gaining sufficient contrast between the dot and the target. Because the dot is presented in a blacked out field, the eye looking into the sight sees plenty of contrast. Moreover, the Singlepoint needs no batteries. Enough ambient light to illuminate the dot is gathered by the small collector on the end. For a long while, see-through red dot sights needed to use polarizers to darken the target image so you could make out the dot, and they ate batteries like kids going through Crackerjacks

Dot sight technology has come a long way since the early days. Compared to the present day offerings of AimpointEoTech, Trijicon and others, the Singlepoint now seems pretty crude and backward. But we can credit the Singlepoint with helping to get the ball rolling on what has become one of the most significant shooting developments in this century.

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Update, 21 March 2013: I just discovered by accident (I was researching something else) that the occluded eye gunsight has been in existence for quite a long time. It was used in World War One artillery. So far as I know, the Singlepoint was the first commercially successful  application to small arms. Reference:

Elementary optics and applications to fire control instruments: May, 1921, p. 84, By United States Army Ordnance Departmant

10 comments:

  1. It certainly did create a stir in the seventies.
    I bought one of these when I was in the Army in Belfast in 1975 and walked the streets with it.
    That was until the local paper ran a story on 'new weapon sights'.
    We were told that we had to remove them as it gave us an unfair advantage over the paramilitaries.
    PA gone mad even then eh!
    Granted as you say the accuracy of this sight left a lot to be desired, but for a snap shot close quarter situation it was ideal.
    Seeing it again after all these years brings back lots of memories.

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  2. The one pictured above with the 16 MOA dot is for shotguns, There was a rifle model that I believe was 4 MOA dot. Most people have seen this sight and don't realize it, It's the sight used on Imperial blasters in Star Wars.

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    1. Haven't seen one like that myself. The similar Armson OEG has a nominally 4 MOA dot and would likely work better for rifle shooting than the 16 MOA basketball.


      Funny that the Star Wars prop guys thought this futuristic looking; it's a crude early attempt at giving the shooter a heads up aiming pip. But, as our Brit pal points out above, it was pretty good for its time.

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    2. I have one I brought home from Vietnam in 1972...sn# 16126...combat tested since I carried on my Car-15/XM203 while doing recon missions for SOG and there was more than one night fight...MSG Kevin "Snake"Smith USSF (Ret)

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  3. I bough one of these in the late 70's, I mounted it on my ar15. I still have them both. It may be outdated, but I don't worry about batteries. Na na na na na naaaaa.

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    1. Well... Okay. It may be said, in all fairness, that it works as well as it ever did. Furthermore it is rugged and therefore most likely will continue doing what it does.

      I too like the no-batteries aspect, and the good contrast between the dot and its background. The OEG concept has a lot to recommend it. For me its biggest downside is the phoria problem. If both eyes cannot see the target, the alignment of one eye with the other soon starts to wander and your accuracy goes to pot.

      There is a new sight on the market that uses the OEG principle and which may succeed in avoiding the phoria problem. It's the "See All Open SIght" and consists of the lower half of an OEG: You can see over the top of it to maintain visual orientation of both eyes. It's an intriguing concept but I don't know anything about how well it works, as yet. I hope to do a thorough review of it by and by.

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  4. I have one with a green dot. Maybe that was a later model? With a smaller MOA (one might hope)? Seems to me that if the dot's MOA is excessively large, it might still be very useful as a shotgun aiming device. What do you all think?

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    1. Some sources online suggest that there was a green dot version with a 12 MOA dot, which is an improvement, but that's still awful big. Covers a foot at 100 yards.

      Shotgun...I'm not so sure, for shotguns firing shot loads seem to do all right without optics.

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    2. Thanks Kendal. Yes, mine is definitely a 'green dot' model, but I cannot confirm the MOA. If it is 12 MOA, rather than 16, I'm satisfied. If 12 MOA covers a foot at 100 yards, that may be acceptable, for its intended purpose. What I really like about the Single Point is that it is not dependent on batteries. It seems to me that battery life, and other electronic issues, make electronic sights problematic. I agree that the shotgun probably doesn't need optics, although I do recall that Single Point did market a shotgun version.

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    3. Again going on net buzz, not solid facts or firsthand knowledge, the shotgun model had a dot 42 MOA across!

      Measuring MOA is a handy do-it-yourself project. 1 MOA equals (nearly enough as to make no difference) a span of 1 inch at 100 yards, 1/2 inch at 50, 1/4 inch at 25... So you compare what you see to a grid, such as one of those targets ruled in 1 inch squares. Or measure the bricks in a brick wall and compare to that.

      It would appear that whoever designed the Singlepoint liked really big dots. Anywhere from 2 to 5 MOA seems common in red dot rifle sights offered today.

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