What's purpose of the left-eye shield?

I occasionally do competitive matches with handguns (USPSA in the US), so I have some background knowledge. The eye cover is to reduce strain / fatigue from squinting, however it also helps the other eye focus on their aperture sight naturally, thus making it easier to take a more accurate shot (with all of the science behind closing apertures and front sight posts, linked in this thread).

In USPSA, while we don't use eye covers in a match, but a lot of competitors will use them on their dominant eye to practice fast target acquisition, independent of their pistol red dot or iron sights. Translates to very refined muscle memory when you don't need to rely on your optics to align your aim.

In most type of shooting, you're generally NOT closing either of your eyes while aiming. It's counter productive to your situational awareness

A few things. It makes for no distraction in the eye you’re not using, while still allowing you to have both eyes easily open with focus where you need. Keeping both eyes open vastly reduces strain on the facial/eye muscles.

Sometimes a white opaque shield is used, on the theory that allowing light through won’t have potentially negative effects on iris contraction. I can’t speak to the validity of this one.

We use tape over the left eye of my youngest’s eye pro when he’s shooting a rifle. He’s cross eye dominant and scotch tape on the glasses is cheaper than a left handed rifle.

I'm no olympian, but squinting one eye shut can mess up your vision when aiming. Leaving both open takes some extra attention away from the target. I don't shoot competitively, but I leave both eyes open. I assume the same for them.

I'm not a shooter, but people do the same thing when looking through a telescope, or a microscope with one eyepiece. You learn to ignore the other eye.

Looking through a telescope or microscope isn't a competition sports.

Considering the performance of the silver medalist, maybe thousands of hours of practice makes it moot, if you don't train yourself to require it.

Cargo cult, even at the olympic level, is a thing. See the mustaches that make you swim faster [1]. It wasn't only the Russian's that adopted it.

[1] https://swimswam.com/the-legend-of-the-mustache-in-swimming-...

He didn't reach the final in the men's event, so maybe they just had a good day.

I teach drawing and my students are required to measure alignment of objects using their pencil as a straight edge whilst looking through one eye. Some students have trouble with this and have to place one hand over there non dominant eye.

Since I lost my left eye I have no trouble looking through only one eye. However, I have acquired plenty of troubles with balance.

Most shut left eye, an eye patch reduces muscle strain as eye doesn't have to close as tightly

extend your arm, now focus your vision on a tip of your finer, and (still focusing on a finger tip!) try to point your finger just below some small object in the distance of few meters. If you use both your eyes, if done properly it should be impossible because the object you try to point to, but not look at, will be seen double and will move as you move your finger. Then do do same but with one eye closed - now it still should be blurry, but nothing more so you can aim. This is how you aim in shooting (always focusing vision on pistol, never on target) so you need to do it with one eye. You don’t want to keep it shout as this creates additional tension in body, and probably may affect your face after years of training, so simple piece of paper or plastic to shield the eye is enough.

Interesting, I’ve essentially done zero pistol/rifle shooting but I shoot clays regularly and this is pretty much the opposite of the advice you’d give a new clay shooter. Mount the shotgun properly with both eyes open, track the clay, work out the lead, then boom. Is the “focus on the pistol” thing because you’re aiming at a static target?

For precision shooting, the alignment of the sights with each other has a much bigger impact on where you hit than the alignment of the sights with the target. An intuitive explanation for why might be that the distance from either sight to the target is much greater than the distance between the sights, so a misalignment between the sights creates a much larger angle than the same amount of misalignment with the target.

Yes, for pistol shooting iron sights (just learned the english term, that’s what I meant by “focus on pistol” ;) ) are what you have to focus on. The target is black bulls eye, clearly visible on a white background, even if it’s blurry.Then you aim just below the bulls eye - so what you se is black iron sights (vision focus, sharp), then small white gap, then blurry black bulls eye. And then you learn to have all those elements spaced exactly the same on every single repetition.

You don’t have to track target, as it’s always in the same spot.

That’s for bullseye style shooting. In other pistol formats like ipsc sight focus shooting is too slow. Target focused is the way top competitors shoot.

What I’m curious about is the rapid fire Olympic event. It’s not particularly fast as these things go but very accurate (though less so than the other events).

It's basically the same, just with a lot more of a "good enough" attitude to aiming. So you really mostly on a muscle memory to have pistol somewhere in a target, then aim using iron sights. For whole 8,6 or 4s you focus vision on a iron sights. During the first phase - moving your arm up from the 45 degree position, you look in the target direction so you know when to start, then focus your vision on iron sights in the end phase of raising arm motion so you are almost immediately ready to aim and pull the trigger, then just move you eyes to the next target, but with "locked" focus (at the distance of iron sights, not target), so again, arm moves to the target area and you can aim and shoot.

I know you must know this, but for others reading, this also is not a static view, like in a video game, but the sights are 'swimming' around usually in a figure 8 pattern as your heart beats. It is not just a matter of getting a good sight picture, but breaking the trigger when things aren't perfectly lined up, because by the time the mechanism fires and the projectile leaves the barrel you will no longer be lined up. This is worse for air pistol due to the slow velocity of the pellet.

In other words it is not like you are holding a tiny dot in the exact center of a circle, it is a messy blur of trying to hold 3 things in alignment where the front sight is about as big as the entire bullseye (hence why you aim below, so there is white visible, you would otherwise obscure the target entirely.

If you do it well, you are consistently hitting something the size of the period at the end of this sentence from 10 meters away (again, air pistol).

Ex-military guys give the same advice of keeping both eyes open. It doesn't seem to apply to bullseye shooting, though.

I shoot quite often. If you learn to shoot with your left right shut you will need to calibrate your sight to shoot for something I know as a 'counter-paralax'. When i say "left eye" that might be your right eye, it depends on how you shoot. You cannot calibrate a sight properly without choosing left, right, or having both eyes open...

Both eyes are preferred for a killer, because you want to have awareness. But it is not an easy way to shoot, or train, or learn.

On another note, I had a cal .22 blow on my face once, on a perfectly tuned rifle, and the reason I kept my eye, is because the exit is on the right hand side. Most rifles are build like that.

"Both eyes are preferred for a killer, because you want to have awareness. But it is not an easy way to shoot, or train, or learn."

I think you're entirely wrong, but the sport USPSA is vastly different from any Olympic style shooting you would seen. It's speed and hit factor (that is, the caliber of your gun as a TLDR). Different priorities than Olympic sharpshooting.

You need to take a pistol class from Shrek (sob tactical). He will change your way of thinking about your eyes and shooting

Bloke on the range goes into this in his video[1] on olympic pistol target shooting.

For him it helps to block his non-dominant eye as he has a weak dominant eye.

Also, the pupil responses are linked, so you'd want both eyes to be exposed to similar brightness. So you don't want to close it or wear a patch.

[1]: https://www.youtube.com/watch?v=zfaK4Hz0Na8