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Solution for old eyes

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Spent my first day as a vendor at Friendship, IN, at the muzzle loading championships. I'm new to muzzleloading. I'm a Service Rifle shooter, retired engineer who studied optics at MIT, photographer, and I'm old enough my near vision went, so I studied the optics of the human eye and developed the solution for shooters. I have been doing corrective lenses for shooters for 10 years, and was recently told at Camp Perry that I need to talk to the muzzle loading community, especially since I live in Cincinnati, right next to Friendship. So ...

Definition 1: Depth of Field (DoF). Your eye only has one theoretical focal point at any particular moment, however if the width of the blur line of an 'out of focus' object is smaller than the distance between two photoreceptors on your retina, you cannot see it. Hence the theoretical focal 'point' is actually a range including some distances closer than the focal point, and some distances further than the focal point. How big your DoF is, is determined by the size of the aperture you are looking through.

Definition 2: Aperture. The smallest opening in your optical path. Within reason, does not matter where it is. It might be your pupil, it might be an aperture sight on the rifle, or it could be a sticker with a small hole drilled in it that you have stuck onto your eyeglasses, or a merit disk. When people find that they can focus better with more light, it is not actually because of the increased light, it is because the increased light makes the pupil in your eye constrict, reducing aperture size, improving your eye's natural depth of field.

Definition 3: Diopter. A measure of lens strength, based on how much it shifts your focal point. The relaxed (or corrected) human eye focuses at infinity. If you add a positive diopter lens, it will shift your focal point closer without your eye making an effort. The adjusted focal point will be the inverse of the diopter strength, in meters. eg, if you add +2.00 diopters (typical reading glasses strength), your relaxed eye will be focused at 1/2 meter, about 20", good arm length for reading. Some people prefer +2.50 diopters, 1/2.5 = 40 cm = 16". +3.0 diopters is 1/3 meter which, if you remember the old 12" rulers that were 30cm on the other side. Reciprocals work too: +0.50 diopters = 1/2 diopter = 2 meter = 8 feet. These are awesome for watching television. The human eye can detect changes in focus about as small as 1/8 diopter = 0.125. So basically, from +0.125 = 8 meters, out to 0 diopters = 1/0 = infinity meters, it all looks the same. So basically, all targets are at optical infinity.

A sight picture needs two things: for your eye to have a good depth of field, and your point of focus must be at a distance so the depth of field is centered between your sights and the target (referred to as the hyperfocal distance in photography). Ideally, your depth of field is big enough that the sights are in the near edge of your depth of field, at the same time as your target is in the far edge of your depth of field. This part of my theory is a departure from the old adage 'focus on the front sight'. It might be OK to concentrate on the front sight, but if you truly focus ON the front sight, your target is too blurry. By focusing at the hyperfocal, you have slight blur on the target, and slight blur on the sight, but the clarity looks balanced.

As stated, the relaxed (or corrected) human eye focuses at infinity. You exert the ciliary muscle in your eye to squeeze the lens, which brings your focal point closer. You relax the muscle, and the lens' elasticity restores focus to infinity. At around age 40, the lens loses it's elasticity, and the muscle has to struggle harder to focus up close. For really close, you cannot do it, for medium close, you can do it for a few seconds, and the muscle tires and fades. Another way to bring your focus in closer is to add a positive diopter lens in front of your eye, aka reading glasses or a bifocal if you have distance correction. Lens power relates to focal distance, however standard reading glasses are typically MUCH too strong to shoot with.

Seeing the front sight is a 'middle distance' where shooters struggle. With a rear aperture, the correct answer on a rifle is to add +0.50 diopters of lens, because you are balancing focus between front sight and target, leaving the aperture fuzzy. This is way weaker than reading glasses. With pistol, where the sights are closer, you want to add +0.75 to +1.00 (depending on how blurry you like the target). I had never experimented with buckhorn sights, but most people I worked with today preferred a +0.50 lens, so they were concerned with balancing the front sight and the target, and were willing to let the buckhorn be blurry. To be clear, with a +0.50, the buckhorn will be less blurry than if you were just shooting with your eye, but not very clear. I'll be back tomorrow and gather more data as to what people like.

Bottom line, to see your sights like you did when you were 18, you need to use a +0.50 lens. An aperture in the sight, or on your eyeglasses makes it even better. I heard lots of 'oh, wow' when I held up the right lens with an aperture for shooters.

Art Neergaard
 
Best I've found is 1.0 reader glasses. An aperture tang sight by itself seems to correct for the double front sight image just fine, but it is even better with the glasses. Trying to squint at the sights seems to change the shape of the aperture while keeping eyes wide open produces a nice round aperture.

You are right about the depth of field increase in good light. This will be even more noticeable if you are shooting over snow.

Haven't tried drilling an aperture into a cheap pair of sunglasses yet. Maybe next week.

Sucks gettin' old, don't it?
 
I'm using 0.5 safety glasses, seem to help quite a bit. Even with them a fine front sight is hard to see. Every day I have 2.0 reading glasses and my optometrist has suggested I'm could use some prescription.

Someone politely called me sir the other day, I said I wasn't old enough (61) but that my dad was (91).
 
Spent my first day as a vendor at Friendship, IN, at the muzzle loading championships. I'm new to muzzleloading. I'm a Service Rifle shooter, retired engineer who studied optics at MIT, photographer, and I'm old enough my near vision went, so I studied the optics of the human eye and developed the solution for shooters. I have been doing corrective lenses for shooters for 10 years, and was recently told at Camp Perry that I need to talk to the muzzle loading community, especially since I live in Cincinnati, right next to Friendship. So ...

Definition 1: Depth of Field (DoF). Your eye only has one theoretical focal point at any particular moment, however if the width of the blur line of an 'out of focus' object is smaller than the distance between two photoreceptors on your retina, you cannot see it. Hence the theoretical focal 'point' is actually a range including some distances closer than the focal point, and some distances further than the focal point. How big your DoF is, is determined by the size of the aperture you are looking through.

Definition 2: Aperture. The smallest opening in your optical path. Within reason, does not matter where it is. It might be your pupil, it might be an aperture sight on the rifle, or it could be a sticker with a small hole drilled in it that you have stuck onto your eyeglasses, or a merit disk. When people find that they can focus better with more light, it is not actually because of the increased light, it is because the increased light makes the pupil in your eye constrict, reducing aperture size, improving your eye's natural depth of field.

Definition 3: Diopter. A measure of lens strength, based on how much it shifts your focal point. The relaxed (or corrected) human eye focuses at infinity. If you add a positive diopter lens, it will shift your focal point closer without your eye making an effort. The adjusted focal point will be the inverse of the diopter strength, in meters. eg, if you add +2.00 diopters (typical reading glasses strength), your relaxed eye will be focused at 1/2 meter, about 20", good arm length for reading. Some people prefer +2.50 diopters, 1/2.5 = 40 cm = 16". +3.0 diopters is 1/3 meter which, if you remember the old 12" rulers that were 30cm on the other side. Reciprocals work too: +0.50 diopters = 1/2 diopter = 2 meter = 8 feet. These are awesome for watching television. The human eye can detect changes in focus about as small as 1/8 diopter = 0.125. So basically, from +0.125 = 8 meters, out to 0 diopters = 1/0 = infinity meters, it all looks the same. So basically, all targets are at optical infinity.

A sight picture needs two things: for your eye to have a good depth of field, and your point of focus must be at a distance so the depth of field is centered between your sights and the target (referred to as the hyperfocal distance in photography). Ideally, your depth of field is big enough that the sights are in the near edge of your depth of field, at the same time as your target is in the far edge of your depth of field. This part of my theory is a departure from the old adage 'focus on the front sight'. It might be OK to concentrate on the front sight, but if you truly focus ON the front sight, your target is too blurry. By focusing at the hyperfocal, you have slight blur on the target, and slight blur on the sight, but the clarity looks balanced.

As stated, the relaxed (or corrected) human eye focuses at infinity. You exert the ciliary muscle in your eye to squeeze the lens, which brings your focal point closer. You relax the muscle, and the lens' elasticity restores focus to infinity. At around age 40, the lens loses it's elasticity, and the muscle has to struggle harder to focus up close. For really close, you cannot do it, for medium close, you can do it for a few seconds, and the muscle tires and fades. Another way to bring your focus in closer is to add a positive diopter lens in front of your eye, aka reading glasses or a bifocal if you have distance correction. Lens power relates to focal distance, however standard reading glasses are typically MUCH too strong to shoot with.

Seeing the front sight is a 'middle distance' where shooters struggle. With a rear aperture, the correct answer on a rifle is to add +0.50 diopters of lens, because you are balancing focus between front sight and target, leaving the aperture fuzzy. This is way weaker than reading glasses. With pistol, where the sights are closer, you want to add +0.75 to +1.00 (depending on how blurry you like the target). I had never experimented with buckhorn sights, but most people I worked with today preferred a +0.50 lens, so they were concerned with balancing the front sight and the target, and were willing to let the buckhorn be blurry. To be clear, with a +0.50, the buckhorn will be less blurry than if you were just shooting with your eye, but not very clear. I'll be back tomorrow and gather more data as to what people like.

Bottom line, to see your sights like you did when you were 18, you need to use a +0.50 lens. An aperture in the sight, or on your eyeglasses makes it even better. I heard lots of 'oh, wow' when I held up the right lens with an aperture for shooters.

Art Neergaard
Where would one find a +0.50 lens? I've never seen one. Or would I need to request them from an optometrist?
 
Best I've found is 1.0 reader glasses. An aperture tang sight by itself seems to correct for the double front sight image just fine, but it is even better with the glasses. Trying to squint at the sights seems to change the shape of the aperture while keeping eyes wide open produces a nice round aperture.

You are right about the depth of field increase in good light. This will be even more noticeable if you are shooting over snow.

Haven't tried drilling an aperture into a cheap pair of sunglasses yet. Maybe next week.

Sucks gettin' old, don't it?
Yep 1.0 glasses is what I use too. Shoot for the middle of the black blur.
 
Spent my first day as a vendor at Friendship, IN, at the muzzle loading championships. I'm new to muzzleloading. I'm a Service Rifle shooter, retired engineer who studied optics at MIT, photographer, and I'm old enough my near vision went, so I studied the optics of the human eye and developed the solution for shooters. I have been doing corrective lenses for shooters for 10 years, and was recently told at Camp Perry that I need to talk to the muzzle loading community, especially since I live in Cincinnati, right next to Friendship. So ...

Definition 1: Depth of Field (DoF). Your eye only has one theoretical focal point at any particular moment, however if the width of the blur line of an 'out of focus' object is smaller than the distance between two photoreceptors on your retina, you cannot see it. Hence the theoretical focal 'point' is actually a range including some distances closer than the focal point, and some distances further than the focal point. How big your DoF is, is determined by the size of the aperture you are looking through.

Definition 2: Aperture. The smallest opening in your optical path. Within reason, does not matter where it is. It might be your pupil, it might be an aperture sight on the rifle, or it could be a sticker with a small hole drilled in it that you have stuck onto your eyeglasses, or a merit disk. When people find that they can focus better with more light, it is not actually because of the increased light, it is because the increased light makes the pupil in your eye constrict, reducing aperture size, improving your eye's natural depth of field.

Definition 3: Diopter. A measure of lens strength, based on how much it shifts your focal point. The relaxed (or corrected) human eye focuses at infinity. If you add a positive diopter lens, it will shift your focal point closer without your eye making an effort. The adjusted focal point will be the inverse of the diopter strength, in meters. eg, if you add +2.00 diopters (typical reading glasses strength), your relaxed eye will be focused at 1/2 meter, about 20", good arm length for reading. Some people prefer +2.50 diopters, 1/2.5 = 40 cm = 16". +3.0 diopters is 1/3 meter which, if you remember the old 12" rulers that were 30cm on the other side. Reciprocals work too: +0.50 diopters = 1/2 diopter = 2 meter = 8 feet. These are awesome for watching television. The human eye can detect changes in focus about as small as 1/8 diopter = 0.125. So basically, from +0.125 = 8 meters, out to 0 diopters = 1/0 = infinity meters, it all looks the same. So basically, all targets are at optical infinity.

A sight picture needs two things: for your eye to have a good depth of field, and your point of focus must be at a distance so the depth of field is centered between your sights and the target (referred to as the hyperfocal distance in photography). Ideally, your depth of field is big enough that the sights are in the near edge of your depth of field, at the same time as your target is in the far edge of your depth of field. This part of my theory is a departure from the old adage 'focus on the front sight'. It might be OK to concentrate on the front sight, but if you truly focus ON the front sight, your target is too blurry. By focusing at the hyperfocal, you have slight blur on the target, and slight blur on the sight, but the clarity looks balanced.

As stated, the relaxed (or corrected) human eye focuses at infinity. You exert the ciliary muscle in your eye to squeeze the lens, which brings your focal point closer. You relax the muscle, and the lens' elasticity restores focus to infinity. At around age 40, the lens loses it's elasticity, and the muscle has to struggle harder to focus up close. For really close, you cannot do it, for medium close, you can do it for a few seconds, and the muscle tires and fades. Another way to bring your focus in closer is to add a positive diopter lens in front of your eye, aka reading glasses or a bifocal if you have distance correction. Lens power relates to focal distance, however standard reading glasses are typically MUCH too strong to shoot with.

Seeing the front sight is a 'middle distance' where shooters struggle. With a rear aperture, the correct answer on a rifle is to add +0.50 diopters of lens, because you are balancing focus between front sight and target, leaving the aperture fuzzy. This is way weaker than reading glasses. With pistol, where the sights are closer, you want to add +0.75 to +1.00 (depending on how blurry you like the target). I had never experimented with buckhorn sights, but most people I worked with today preferred a +0.50 lens, so they were concerned with balancing the front sight and the target, and were willing to let the buckhorn be blurry. To be clear, with a +0.50, the buckhorn will be less blurry than if you were just shooting with your eye, but not very clear. I'll be back tomorrow and gather more data as to what people like.

Bottom line, to see your sights like you did when you were 18, you need to use a +0.50 lens. An aperture in the sight, or on your eyeglasses makes it even better. I heard lots of 'oh, wow' when I held up the right lens with an aperture for shooters.

Art Neergaard
 
Spent my first day as a vendor at Friendship, IN, at the muzzle loading championships. I'm new to muzzleloading. I'm a Service Rifle shooter, retired engineer who studied optics at MIT, photographer, and I'm old enough my near vision went, so I studied the optics of the human eye and developed the solution for shooters. I have been doing corrective lenses for shooters for 10 years, and was recently told at Camp Perry that I need to talk to the muzzle loading community, especially since I live in Cincinnati, right next to Friendship. So ...

Definition 1: Depth of Field (DoF). Your eye only has one theoretical focal point at any particular moment, however if the width of the blur line of an 'out of focus' object is smaller than the distance between two photoreceptors on your retina, you cannot see it. Hence the theoretical focal 'point' is actually a range including some distances closer than the focal point, and some distances further than the focal point. How big your DoF is, is determined by the size of the aperture you are looking through.

Definition 2: Aperture. The smallest opening in your optical path. Within reason, does not matter where it is. It might be your pupil, it might be an aperture sight on the rifle, or it could be a sticker with a small hole drilled in it that you have stuck onto your eyeglasses, or a merit disk. When people find that they can focus better with more light, it is not actually because of the increased light, it is because the increased light makes the pupil in your eye constrict, reducing aperture size, improving your eye's natural depth of field.

Definition 3: Diopter. A measure of lens strength, based on how much it shifts your focal point. The relaxed (or corrected) human eye focuses at infinity. If you add a positive diopter lens, it will shift your focal point closer without your eye making an effort. The adjusted focal point will be the inverse of the diopter strength, in meters. eg, if you add +2.00 diopters (typical reading glasses strength), your relaxed eye will be focused at 1/2 meter, about 20", good arm length for reading. Some people prefer +2.50 diopters, 1/2.5 = 40 cm = 16". +3.0 diopters is 1/3 meter which, if you remember the old 12" rulers that were 30cm on the other side. Reciprocals work too: +0.50 diopters = 1/2 diopter = 2 meter = 8 feet. These are awesome for watching television. The human eye can detect changes in focus about as small as 1/8 diopter = 0.125. So basically, from +0.125 = 8 meters, out to 0 diopters = 1/0 = infinity meters, it all looks the same. So basically, all targets are at optical infinity.

A sight picture needs two things: for your eye to have a good depth of field, and your point of focus must be at a distance so the depth of field is centered between your sights and the target (referred to as the hyperfocal distance in photography). Ideally, your depth of field is big enough that the sights are in the near edge of your depth of field, at the same time as your target is in the far edge of your depth of field. This part of my theory is a departure from the old adage 'focus on the front sight'. It might be OK to concentrate on the front sight, but if you truly focus ON the front sight, your target is too blurry. By focusing at the hyperfocal, you have slight blur on the target, and slight blur on the sight, but the clarity looks balanced.

As stated, the relaxed (or corrected) human eye focuses at infinity. You exert the ciliary muscle in your eye to squeeze the lens, which brings your focal point closer. You relax the muscle, and the lens' elasticity restores focus to infinity. At around age 40, the lens loses it's elasticity, and the muscle has to struggle harder to focus up close. For really close, you cannot do it, for medium close, you can do it for a few seconds, and the muscle tires and fades. Another way to bring your focus in closer is to add a positive diopter lens in front of your eye, aka reading glasses or a bifocal if you have distance correction. Lens power relates to focal distance, however standard reading glasses are typically MUCH too strong to shoot with.

Seeing the front sight is a 'middle distance' where shooters struggle. With a rear aperture, the correct answer on a rifle is to add +0.50 diopters of lens, because you are balancing focus between front sight and target, leaving the aperture fuzzy. This is way weaker than reading glasses. With pistol, where the sights are closer, you want to add +0.75 to +1.00 (depending on how blurry you like the target). I had never experimented with buckhorn sights, but most people I worked with today preferred a +0.50 lens, so they were concerned with balancing the front sight and the target, and were willing to let the buckhorn be blurry. To be clear, with a +0.50, the buckhorn will be less blurry than if you were just shooting with your eye, but not very clear. I'll be back tomorrow and gather more data as to what people like.

Bottom line, to see your sights like you did when you were 18, you need to use a +0.50 lens. An aperture in the sight, or on your eyeglasses makes it even better. I heard lots of 'oh, wow' when I held up the right lens with an aperture for shooters.

Art Neergaard
Excellent explanation of "Optometristese" As my preacher says, "You gotta put the feed out there where the calves can reach it." You've certainly done that my friend.
 
I have been living with three pairs of glasses for a long time and my job as a watchmaker did not help me to keep good eyes, now I am seventy-five years old, and the old age is felt in addition to my poor eyesight from birth...
To be able to shoot correctly, I use glasses with medium-distance glass (not long-distance) and very short-distance glass to be able to load a weapon correctly. On the medium distance lens, I have installed a Lyman Eyepal which I use for shooting, and it is perfect, I can see the aiming instruments perfectly. The second lens, short distance, is only used to load and handle my small stuff...

Lyman Eyepal: You are being redirected...
 
I have been living with three pairs of glasses for a long time and my job as a watchmaker did not help me to keep good eyes, now I am seventy-five years old, and the old age is felt in addition to my poor eyesight from birth...
To be able to shoot correctly, I use glasses with medium-distance glass (not long-distance) and very short-distance glass to be able to load a weapon correctly. On the medium distance lens, I have installed a Lyman Eyepal which I use for shooting, and it is perfect, I can see the aiming instruments perfectly. The second lens, short distance, is only used to load and handle my small stuff...

Lyman Eyepal: You are being redirected...
I'll have to check that out.thanks!
 
Spent my first day as a vendor at Friendship, IN, at the muzzle loading championships. I'm new to muzzleloading. I'm a Service Rifle shooter, retired engineer who studied optics at MIT, photographer, and I'm old enough my near vision went, so I studied the optics of the human eye and developed the solution for shooters. I have been doing corrective lenses for shooters for 10 years, and was recently told at Camp Perry that I need to talk to the muzzle loading community, especially since I live in Cincinnati, right next to Friendship. So ...

Definition 1: Depth of Field (DoF). Your eye only has one theoretical focal point at any particular moment, however if the width of the blur line of an 'out of focus' object is smaller than the distance between two photoreceptors on your retina, you cannot see it. Hence the theoretical focal 'point' is actually a range including some distances closer than the focal point, and some distances further than the focal point. How big your DoF is, is determined by the size of the aperture you are looking through.

Definition 2: Aperture. The smallest opening in your optical path. Within reason, does not matter where it is. It might be your pupil, it might be an aperture sight on the rifle, or it could be a sticker with a small hole drilled in it that you have stuck onto your eyeglasses, or a merit disk. When people find that they can focus better with more light, it is not actually because of the increased light, it is because the increased light makes the pupil in your eye constrict, reducing aperture size, improving your eye's natural depth of field.

Definition 3: Diopter. A measure of lens strength, based on how much it shifts your focal point. The relaxed (or corrected) human eye focuses at infinity. If you add a positive diopter lens, it will shift your focal point closer without your eye making an effort. The adjusted focal point will be the inverse of the diopter strength, in meters. eg, if you add +2.00 diopters (typical reading glasses strength), your relaxed eye will be focused at 1/2 meter, about 20", good arm length for reading. Some people prefer +2.50 diopters, 1/2.5 = 40 cm = 16". +3.0 diopters is 1/3 meter which, if you remember the old 12" rulers that were 30cm on the other side. Reciprocals work too: +0.50 diopters = 1/2 diopter = 2 meter = 8 feet. These are awesome for watching television. The human eye can detect changes in focus about as small as 1/8 diopter = 0.125. So basically, from +0.125 = 8 meters, out to 0 diopters = 1/0 = infinity meters, it all looks the same. So basically, all targets are at optical infinity.

A sight picture needs two things: for your eye to have a good depth of field, and your point of focus must be at a distance so the depth of field is centered between your sights and the target (referred to as the hyperfocal distance in photography). Ideally, your depth of field is big enough that the sights are in the near edge of your depth of field, at the same time as your target is in the far edge of your depth of field. This part of my theory is a departure from the old adage 'focus on the front sight'. It might be OK to concentrate on the front sight, but if you truly focus ON the front sight, your target is too blurry. By focusing at the hyperfocal, you have slight blur on the target, and slight blur on the sight, but the clarity looks balanced.

As stated, the relaxed (or corrected) human eye focuses at infinity. You exert the ciliary muscle in your eye to squeeze the lens, which brings your focal point closer. You relax the muscle, and the lens' elasticity restores focus to infinity. At around age 40, the lens loses it's elasticity, and the muscle has to struggle harder to focus up close. For really close, you cannot do it, for medium close, you can do it for a few seconds, and the muscle tires and fades. Another way to bring your focus in closer is to add a positive diopter lens in front of your eye, aka reading glasses or a bifocal if you have distance correction. Lens power relates to focal distance, however standard reading glasses are typically MUCH too strong to shoot with.

Seeing the front sight is a 'middle distance' where shooters struggle. With a rear aperture, the correct answer on a rifle is to add +0.50 diopters of lens, because you are balancing focus between front sight and target, leaving the aperture fuzzy. This is way weaker than reading glasses. With pistol, where the sights are closer, you want to add +0.75 to +1.00 (depending on how blurry you like the target). I had never experimented with buckhorn sights, but most people I worked with today preferred a +0.50 lens, so they were concerned with balancing the front sight and the target, and were willing to let the buckhorn be blurry. To be clear, with a +0.50, the buckhorn will be less blurry than if you were just shooting with your eye, but not very clear. I'll be back tomorrow and gather more data as to what people like.

Bottom line, to see your sights like you did when you were 18, you need to use a +0.50 lens. An aperture in the sight, or on your eyeglasses makes it even better. I heard lots of 'oh, wow' when I held up the right lens with an aperture for shooters.

Art Neergaard
Several years ago, I ran up against the problem of not being able to get the front sight in focus. I consulted my optometrist (a shooter) who suggested I bring a pistol mock-up (I took a a pellet gun), and she put the changeable-lens glasses on me and swapped a few lenses back and forth until I got a comfortable front sight focus with my dominant eye only. I got a pair of glasses made, and viola! problem solved! (plus they are great at the computer) As you said, the difference was only about 1 diopter, longer distances are slightly blurry, but still within legal driving limits. I use them for archery as well.
 
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