Unable to focus on sights

[gimgim]

Since about one year ago, when I had a lens for the Varga frame made, my eye got worse (I am 55 y/o) and I have to go again to my optometrist.
What's annoying/weird though is that, with the current setting, when I lift the pistol I can initially focus for a short time on the front sight.
As I keep aiming, both front and rear sights become very blurry (target is blurry as well, I am not focusing on that) and no matter what, I can't get back to a sharp sight. The same happens when shooting on the back of the target; I have double checked to make sure I wasn't switching focus on the target without being aware of it :-).
Has anybody else experienced the same?
Thanks

[David M]

At your age your eyes can change quickly, then in a couple of years they seem to settle down.
Do the eye test and see.
The ideal focal length seems to me about one metre in front of the foresight.

[Leon]

My eyes seem to change just about every day...

After spending an hour or two changing and rotating lenses in a Knobloch lens holder, I often find that yesterday's perfect eye sight lacks crispness, and is slightly out astigmatically today.

So, I am thinking of getting a VarioLens 2 +. The original version was criticized for being a tad heavy, so the latest iteration of the VarioLens 2 is a lot lighter....

http://www.variolens.de/english.html

Another tempting, and much cheaper, alternative is this -

https://www.amazon.com/gp/product/B01HD ... 0DER&psc=1

You can order regular lenses for your non dominant eye on their website. Better yet you can order bottom bifocals for your non dominant eye so you can see bullet calibers etc .
You can have a complete mix & match kit for under $70 and can easily swap lenses to your current eyesight needs ..

BTW, sorry to the OP if I have hijacked his thread....

[jetpoweredchicken]

Typically, your glasses prescription plus about .50 to.75 dioptoer correction should place a relaxed eye focus at or about your front sight.
There are a number of things that can cause this to vary. Discuss with your optometrist/opthamologist. You may need to experiment to find right lens.
TALK TO YOU DOC about how to set this up and save a lot of trouble and cost.
Also as your prescription gets stronger, you are going to notice the target ball getting fuzzier and fuzzier. Your brain can still find the right place to hold, but it will take a bit. Just one of those things.
Jet

[divingin]

So, I am thinking of getting a VarioLens 2 +. The original version was criticized for being a tad heavy, so the latest iteration of the VarioLens 2 is a lot lighter....

http://www.variolens.de/english.html

Another tempting, and much cheaper, alternative is this -

https://www.amazon.com/gp/product/B01HD ... 0DER&psc=1

I used a set of Adlens adjustable glasses to see if shooting glasses would work for me. While I wouldn't suggest the use of Adlens glasses as an end solution, the technology works well in letting you see how things change day to day (or, I suppose, hour to hour in some cases.)

The Variolens looks to be a more elegant (if pricier), and more permanent solution along the same lines.

I ended up with a set of Champion frames, a corrective lens, and additional diopters as needed (-1.25 for most pistols, -1.00 for free pistol due to the longer sight radius.) The $39 for the Adlens prevented any kind of worry that I was buying the frames and accessories and having them not work for me.

[trev]

Please do not use this link http://www.variolens.de/english.html as it is for Surrey Guns here in England and they went bust in a big way about two years ago. So don't go sending any money to this link.

[Leon]

Please do not use this link http://www.variolens.de/english.html as it is for Surrey Guns here in England and they went bust in a big way about two years ago. So don't go sending any money to this link.

Thanks for the heads up on this....

[gimgim]

Thank you for the suggestions I like the idea of variable focus lenses, but knowing the correction and getting a fixed lens would be preferable for me.
The problem with my optometrist is that I can't bring the pistol there; last time I brought a stick with sights at the right distance, but it was too much trouble. And in any case, the exam is indoor, with artificial light. I see more issues when shooting FP @50 yards, outdoor.

An option I am considering is to get a few trial lenses in the ballpark of my current prescription to experiment with (see https://www.ebay.com/itm/Metal-Rim-Tria ... 1125682200) and then get a lens done properly with the right setting.

Incidentally, the diameter of the trial lenses, seems to match closely what pistol frames use.

[Rover]

Stop fooling around with that Doc and get one that will work with you. You absolutely don't want variable focus glasses. Get the RIGHT scrip and use it, though you may need a new one in a couple of years.

[atomicgale]

Contact Art at Shooting Sight.

Art is an engineer and extremely dedicated to the optics craft. After an extended dialog, he set me up in a +3.75 by 42mm lens on Champion Olympic frames. Add an adjustable iris set to a "pin-hole" & I can now actually see a clear front sight on a defined target.

Note, my eyes are "RK-survivors from 1992" and add a massive orbital injury in 2005 (yeah, yeah, I know - +3.75 WTF?)

The limiter now (or additional skill) is keeping my head perfectly still to keep the iris in line. This is manifested in neck and left shoulder soreness, however, ACTUALLY BEING ABLE TO SEE - WOW - WHAT A CONCEPT!!!

Good luck!

[gimgim]

> Contact Art at Shooting Sight.

That's my intention once I know the prescription. I have done that in the past (current lens) and all I can say is that it was a great experience.
For the iris, I have it mounted on the lens, but it's not enough tho fix this problem.

[Leon]

Just an idea gimgim, but why don't you try shooting with both eyes closed ?

This way you can eliminate both the annoying and distracting target, and the sights.

If the Japanese Zen archers can do it, so can you !

:)

[gimgim]

> Just an idea gimgim, but why don't you try shooting with both eyes closed ?

What you say may be smarter than you think :-)
After shooting a few times to the back of the target, I am now shooting without any correction.
The sights are in focus, but the target is a complete blur.
I am about 5% worse than my usual (low) scores, so....

(working as expected, of course, still surprising when you experience it)

> If the Japanese Zen archers can do it, so can you !

Herrigel docet...

[Leon]

Gimgim, I have another helpful hint for you.

It might take a little fiddling at the range, but I'm sure if you persevere, you will end up with perfect vision ! :)

[thirdwheel]

Leon
This is exactly the route I've gone down and my eyesight is not that far out, but I want perfect (this is a precision sport after all) and opticians here were going for best guess. Read what Don Nygord has said in the matter in the past, he was spot on.

[gimgim]

> Gimgim, I have another helpful hint for you.

Leon, this is what I did. In my case I already know the old prescription and the direction in which my eyesight is getting worse, so I don't need the full set. I've got a couple of these in .25 steps from my current shooting prescription: https://www.ebay.com/itm/Metal-Rim-Tria ... 1125682200

[ShootingSight]

I actually sell reduced trial lens sets for shooters, but have discouraged people from buying them these past few years, since I figured out the optical math and how it applies to shooting.

Let me start with a simplified definition of diopters and how they apply to your eye: 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. Sounds complicated, but the math is actually easier. 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. The inverse of 1 is still 1, so a 1 diopter focuses at 1 meter. Inverse works too: if I add a 1/2 diopter lens, I'll focus at 2 meters. in-between powers work, but you might need a calculator, a +2.25 lens is 9/4 diopters in fractional notation, so you'd focus at 4/9 meters .... or just use a calculator to calculate the inverse of 2.25 and find out you will focus at 0.44 meters. One other example of note: adding a zero diopter lens (same as adding no lens, or looking through flat glass) will focus you at 1/0, which is infinity. Since your eye started at infinity, this is the same as saying that adding no lens does nothing, but we knew that.

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, ie 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.

So much for diopters.

What you used to do when you were young is that your eye muscle can exert to re-shape the lens in your eye and add internal diopters to focus up close. As you get old, the lens loses its flexibility and you cannot naturally focus up close, so we turn to the solution of reading glasses, adding extra diopters so the lens shifts our focus where we want it to be. Reading often calls for about 2 to 2.5 diopters, as 1/2 meter corresponds to arm length for a lot of people. Working at your computer with the screen around 0.8 meters away might call for 1.25 diopters.

As I said, diopters add, so if you have a distance correction of +3 diopters, and you want to read, you need to add 2 diopters, so this person would use +5 for reading glasses.

Now, for shooting.

What your eye does to see a near by sight and a 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. It's that simple.

For a rifle, the target is at 100 meters, so you would need a 0.01 diopter lens (your eye does not see differences smaller than 0.1 diopters, so this is effectively zero). The front sight is around 1 meter away, so you need a 1.0 diopter to see the sight. So to aim a rifle, you average 1 and 0, and the result is you want to shoot with a +0.50, or you want to add 0.50 to your distance vision prescription if you have a distance correction. So someone with a -2.00 distance correction would add +0.50 and shoot with a -1.50 correction.

Pistols are a little trickier, because you have the rear and the front sight. Since sight alignment is so important, people would rather see the sights a little more clearly, so rather than averaging the front sight and the target, in my experience I average the rear sight and the target. So my rear sight is 24" from me. Converting that to meters is 0.61 meters, and the inverse is 1.64 diopters to see a perfect rear sight. I need 0 diopters to see the target, so my ideal shooting vision is 0.82 diopters (average of 1.64 and zero). Lenses usually come in 1/4 diopter steps, and you want to round down, so 0.82 would be rounded down to +0.75.

Bottom line, use, or add, +0.50 for rifles, +0.75 for pistols. This satisfies 90% of the people I work with. Of course, when I say add, I mean adding to your distance prescription, which means you need to start the process with a current distance prescription. Good news however is that this is just the 'normal' prescription you get from any eye doctor or optometrist. You do not need to find a shooting specialist doctor or arrange to bring your gun to the doctor's office.

There is a whole other theory about adding more power, and offsetting the target blur with apertures, but I will not go into that here. What I gave is an excellent starting point.

Art

[David M]

As we have said for a very long time for Pistol, add +0.5 to +0.75 power to your distance script.
There is a slight performance difference between 10m/25m short barrel and Free pistol 50m long barrel.
But the greatest difference is in the glass tint, yellow for low light, clear (with anti glare coating) for indirect
light and grey tint for full bright sunshine.
Go and get your eyes checked and take a copy of Dr Wongs "BULLSEYE SHOOTERS' GUIDE FOR THE EYECARE PROFESSIONAL".

BULLSEYE SHOOTERS - EyeGuide.doc

(36 KiB) Downloaded 205 times