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Mike in FL

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I inadvertently stumbled on a way to take 30 years off sighting. I'm A little ashamed to say U used to perch big blocky sights on my flintlocks so I could see the sights. Or using adjustable peep sights.
About a year ago I was in a restaurant and picked up a ballpoint to sign the check. Wearing progressive lenses, I held the pen at arms length and tilted my head back to clearly see the point of the pen, if the ball was protruded.
My next stop was at a dollar store where I bought the weakest reading glasses they had, 1.25.
At distance, target bullseye, or squirrel, is a tad fuzzy, but front and rear sights very clear. Try it!
 
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I had similar problems, but the 1.25 reading glasses were too strong. I found some 0.75 and 0.50 readers on Amazon and Ebay. These are very cheap and scratch easily offering very little really in safety protection, but the front sight is in focus, and they do protect from cap fragments. They are cheap enough that after they get too scratched up, I can throw them away and pull out another pair.
 

Semisane

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Yeah, the joy of cheap reading glasses is much appreciated as one grows older (and wiser). I have them in +25 increments from 1.25 to 300 and use different ones for rifles and handguns. The +300's are great when you need to read that ultra-fine print on some things, and for up close work on gun parts and various household do-dads.
 
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I have been buying the magnified safety glasses. I use them for both shooting and woodworking projects. Some of them come marked by “diopter” instead of magnification. There is a conversion formula that converts diopter to magnification but it escapes me right now. I want to say I am buying 2.0 diopter and it is 1.5 magnification.
 

Kmcmichael

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I taught firearms 20 years for our uncle. In addition to new hires I assisted older journeyman. The +1 reading glasses were usually the ticket to keep older eyes on the front sight.
For my flintlocks I do not need correction from distance(from regular prescription) for the front sight due to the longer barrel.
 
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A note of caution. Buying cheap readers for your purpose may be a little short-sighted:cool:. The most shatter resistant lenses are made of polycarbonate. Without knowing what the lenses are made of might put your eyes at risk should "an event" occur. You could wear safety glasses over unknown lenses but just making sure your lenses are poly gives you sight AND protection. Just my 2 cents.
 
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There are stick on diopter lenses available for you to put on any glasses. They are very inexpensive and come in a package with several strengths. This makes it easy to experiment for your own shooting needs. And, yes, the older the shooter is, the further up the barrel the rear sight is moved.
 
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I used to sell professional camera and optical equipment. FYI, a +1 diopter lens allows the eye to remain set as if focused at infinity when actually it is now focused at 1 meter (about 39"), which is about where the front sight would be on a lot of ML rifles. Since the eye can still focus on its own with a diopter lens in front of it, there is some small range of fucus that can be attained. A +2 diopter lens allows the eye in the same infinity scenario to be focused at 1/2 a meter (about 19-20"), and a +3 diopter lens allows focus at 1/3 of a meter (about 13"), and so on. A +0.75 diopter lens allows the eye to focus at 1.3 meters (about 50"), and a +0.5 diopter lens allows focus at 2 meters (about 79"). A diopter of a given strength will allow a lens (whether it be an eye or a camera lens set to focus at infinity) to focus at a distance in yards which is the reciprocal of the diopter number, thus a +10 diopter lens can focus down to 1/10 of a meter (about 4") when set to infinity focus.
 
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Poor eyesight fix that has served me well.
Can purchase a clip-on jewelers loupe like this on Amazon for about $6.00. I replace the loupe's lens with bottom of a 35mm film canister & drill hole size that produces a sharp sight & target picture, a .040 size aperture works well for me.
IMG_2298.JPG
 

Anvilboy

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Poor eyesight fix that has served me well.
Can purchase a clip-on jewelers loupe like this on Amazon for about $6.00. I replace the loupe's lens with bottom of a 35mm film canister & drill hole size that produces a sharp sight & target picture, a .040 size aperture works well for me.
View attachment 155540
Poor man's Merritt Sight!
 
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Poor man's Merritt Sight!
Your correct Anvilboy, this rig actually worked out much better for me than the Merritt sight I used 30 plus years ago before the suction cup lost traction & the spendy unit was lost.
Best part is this jewelers rig pivots out of your line of vision between matches & while hunting & it serves as a peep sight for all your rifles & pistols.
 
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About ten years ago, or less, I dont remember exactly, I had a cataract removed from the right eye and a lens was put in the eye.
I have 20/20 vision in that eye but less in the left eye which has a small cataract that is deemed not worth operating on, so I wear glasses for reading, driving etc.
It disconcerts some shooters on the range when the ‘old fella’ takes his glasses off before shooting !!
 
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I'm new to muzzleloading - actually, I don't even do muzzle loading. I'm a Service Rifle shooter, retired mechanical 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 have never experimented with buckhorn sights, but imagine it will be at least +1.00 if you want to balance focus between the rear sight and the target. If someone can tell me the distance from your eye to the buckhorn, I can run the math and give a quick estimate.

Bottom line, to see your sights like you did when you were 18, you need to use a +0.50 lens, and an aperture sight. If you shoot buckhorns, you likely need a +1.00 lens, and put a sticker with a small hole on your glasses (like eye pal, or make it yourself).

Art Neergaard
ShootingSight llc
www.shootingsight.com
 
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The 18th Century folks figured out that a tang mounted peep sight , "piece of sheet metal 'bout 3/8" wide , and bent at a right angle skyward at the shooter's eye end of the strap of metal". Drill a small , around 3/32" hole , lining up with the eyeball and the rear sight. All this commotion causes the target , and the front sight to be in almost perfect focus. Rear sight can be removed and sold to unknowing gypsies for a good luck charm. Have yer flinter charged up , so when they figger out , there's no luck in the castaway rear sight , thet ye kin run 'em off.
One "O" those "eye surgeon" ladies and I , discussed this "out of focus " stuff over a fresh haunch of venison roasting on a stick. I was real thankful , 'cause she knows stuff about eyes and all.
Hope this explanation helps some of those folks , with challenged heritage , livin' in the low hills of South West Virginia next to the Ohio River . They still teach readin' , writin" , and cypherin" there and none of this "CatPeople , and "lizzard"people live there , like seen on those cell phones.
 
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