Shooting glasses are worn by sport shooters to help them hit the target. They are as much a helping tool, as are a corrective device for persons with vision problems. The glasses are worn mostly by pistol shooters and shotgun shooters. Rifle shooters usually have their vision accessories embedded into the rear diopter, directly on the rifle, but the principles are the same.
Reasons to wear glasses are multiple. The first being the one everybody thinks of, bad eyesight. People that have myopia, meaning that they can see close objects clearly but objects farther away appear blurred, need and usually wear glasses daily. For shooting, the same type of corrective glasses need to be used, but not with the same prescription.
Another reason to wear shooting glasses is to cover the non-shooting eye, especially in precision events.
Yet another reason is to help see better and/or acquire the target faster.
And the last reason is to reduce the field of vision, to better focus on the target and obscure side movement that could lead to distraction.
Glasses are also worn by the majority of shooters simply for protection. For semi-automatic large caliber pistols and for airsoft players they are actually mandatory, because the chance of something rebounding and hitting the shooter in the eye is very high.
Sport shooting glasses are split into 2 categories: the ones that look like normal glasses and the ones that look like some kind of robot device.
The normal glasses are worn usually by athletes that compete in fast moving events, like 25m rapid fire pistol or shotgun trap and skeet. In these events a very good peripheral vision is mandatory because the target is moving or changing.
The adjustable glasses are worn by athletes in precision events, like 10m air pistol. Here the target and the gun stay fixed in position, so the focus is directed in a single point. Of course, there are shooters that use normal glasses for precision events. It’s a matter of preference.
There are also other devices that are worn by shooting athletes, for example headbands that support a simple blinder or a lens. Or a blinder that is clipped on a pair of normal glasses.
A blinder is a piece of material that obscures the vision in the non-aiming eye. Most of the shooters use only one eye to aim, and keep the other closed or covered. There are however some people that can aim with both eyes open.
The eye that is used in aiming is called the dominant eye. It is usually the eye on the side of the dominant arm. For right-handers, it’s the right eye. But there are exceptions to this rule are well, right-handed people that are left eye dominant for example.
The dominant eye is the one that provides a slightly greater degree of input to the visual part of your brain and more accurately relays information about the location of objects.
To establish your dominant eye, extend your arms out in front of you and create a triangular opening between your thumbs and forefingers by placing your hands together at a 45-degree angle. With both eyes open, center this triangular opening on a distant object — such as a wall clock or door knob. Now bring your hands toward your face while keeping the selected object in your vision. When the hands reach your face, they will be centered over your dominant eye, and covering the non-dominant eye. There are also other method to determine the dominant eye.
The adjustable glasses, in addition to being very customizable on where the lens is positioned, also permits the attachment of other accessories. One accessory is the blinder to cover an eye but there are also side and top blinders. Side blinders are no longer allowed in some pistol competitions.
The lens holder can be positioned in such a way that the lens is centered and perpendicular to the eye in the shooting position, which is turned to one side.
Also, on the lens holder can be attached an iris, a color filter or a centering cone.
The iris is a diaphragm like device that is placed on top of the lens in order to increase the depth of field. This makes the target and the rear sight more clear, while focusing on the front sight. It also allows to keep the pupil centered and in the same position and to focus easier on the sights, as it obscures everything else except the pistol and the target. The downside is that the iris reduces the amount of light coming into the eye.
The centering cone is a black cone with a very small opening that is put on top of the lens to help calibrate the lens position. This is done in order to make sure the shooter looks at the target using the center of the lens.
The color filter is a colored lens that is put on top of the normal lens in order to filter out some colors. This is done to increase the contrast of the sights on the target. They are also heavily used in shotgun shooting to increase the contrast of the fast moving orange clay targets against the background, usually green foliage.
The lens is the main motive of wearing glasses. For fast moving events, if you need to correct your vision in normal daily life, use the same prescription. For precision events however, the lens needs to be specially prescribed.
In precision pistol shooting, there are 3 points that need to be aligned: the rear sight, the front sight and the target. The eye cannot focus on 3 distances at once, so the eye must be focused on the front sight. To help the eye focus there, the lens must be made to have the focal length of your arm plus pistol. This will help the eye to naturally focus on the front sight and keep it from focusing on the target. We can say that the lens will make you see worse, because you will see the target blurred no matter how much you try.
There are 2 types of corrective adjustments that can be made on vision: distance (myopia) and astigmatism. For distance, the correction is spherical while for astigmatism, the correction is cylindrical.
If your eye is focused at infinity (which is where the ‘normal’ human eye focuses when relaxed), and you add a positive diopter lens, your relaxed focal point will shift to the inverse of the diopter power, in meters. If you add a +2 lens, you will now be focused at 1/2 meters. If you add a +3, you will be focused at 1/3 meter. Diopters add. If I stack a +2 lens on another +2 lens, that’s the same as having a +4. Diopters can come in negatives: instead of moving your focal point closer, they push it further away. They still add, stacking a +2 on a -2 will cancel each other out.
When you have a distance vision prescription, it means your eye’s natural focal point is *not* at infinity, but somewhere else. Could be closer (near sighted), could be further. What the eye doctor does is measure where it is, and then prescribes you the lens which will cancel it out. So if you are near sighted and naturally focus at 1/2 meter, meaning that your eye effectively has a +2 built in, the doctor will prescribe you a distance correction of -2 to offset the built in +2, and your relaxed eye now effectively has zero correction and you focus at infinity.
For shooting, what your eye does to see the nearby gun sight and the distant target at the same time, is focus between them. That is to say: calculate the diopter to see the target, calculate the diopter to see the sight, and take an average.
For pistol, the eye needs to focus on the front sight that is approximately 1 meter away from the eye. That would mean a +0.75 diopter on the lens. For rifle, a +0.50 diopter is usually used. This is added to the distance prescription of your normal glasses. If you have good vision and don;t need glasses, than it;s just a +0.75 diopter lens for shooting. If you have already distance vision glasses of, for example +1, for shooting a pistol you will need a +1.75 lens.
These diopters that we talked about are spherical correction. If you also have astigmatism, an additional cylindrical correction needs to be added to the lens. The cylindrical correction, in addition to its power, it also has an ax. So the lens will need to be mounted in an exact position in the lens holder for the correction to work.
This is a typical result of an eye exam at the doctor, made by an automated machine that measures the properties of your eyes. Note the 2 columns : SPH for myopia and CYL plus AX for astigmatism. The pistol shooting lens is +0.75 added to the SPH correction.
The best known brands of adjustable shooting glasses are Champion and Knoblock with cheaper alternatives Varga and MEC. There are other brands as well, especially for shotgun glasses.
Shooting glasses are important for everybody, young and old, with good vision or not and they are especially important for protection.