Iron sight shooters - explain this!

[divil]

Something strange happened at the range today. I was shooting an M1 Garand at an indoor range standing and leaning the rifle on my range bag. It was a pretty awkward position, but I noticed something really strange with the sights.

I discovered if I tilted my head forward a certain way, I could sometimes see a different, much sharper sight picture. In particular, the target was much sharper even though I was focusing on the front sight.

The best way I can describe it is like an old CRT TV when something was out of sync, you'd get the picture scrolling up the screen, followed by another copy of the same picture. Well when I tilted my head, the old sight picture "scrolled up" and was replaced by the better one. Or to put it another way, it was like I could somehow look "under" the normal picture. I could stop half way and see half of each.

It was really confusing and I couldn't get the picture consistently enough. But there's no question it was much sharper.

This was totally new to me and I haven't been able to reproduce it at home. I wear glasses for minor astigmatism but I generally see the same out of any part of my glasses.

Has anyone ever experienced this? Any ideas?

[MC 1911]

I get the same thing but mines caused by my glasses. Different picture depending on how I hold my head.

[Wag]

It's a diffraction effect.

More here: https://www.wtamu.edu/~cbaird/sq/201...round-corners/

As light comes around both sides of the sight, it creates a focal point and possibly a very slight degree of magnification right at that spot.

When you move your eyes into that focal point, the clarity of the picture increases.

The effect is pretty minor and depending on the time of day or the lighting at an indoor range, it could be less noticeable.

--Wag--

[divil]

The effect is pretty minor

It was definitely a huge improvement over what I normally see. If I could see that picture all the time I'd be a much better shooter!

[cslinger]

It was definitely a huge improvement over what I normally see. If I could see that picture all the time I'd be a much better shooter!

I shoot iron sighted peep/aperture air rifles quite a lot. I have had crappy vision since I was manufactured and surprise it’s not getting any better as I head to 50. I experience the very same thing and always curse the fact that if I could attain the same sight picture it would really help.

I have noticed a few things shooting with glasses.

-Any tilt of your head might put your eye into a different focus and it can be very difficult to duplicate this as not only do you need to find the right spot like every shooter you also have to deal with the fact your glasses are moving all the time.

-smudges or other crap on your glasses that you may barely notice in normal activities will play hell with shooting focus and precision.

-Your facial movements/resting attributes matter with glasses. Do you shoot better open mouth or closed, squinting or wide eyed, tightly closed off eye or slightly closed etc. etc. these all matter to sight picture not only because of the effect on your shooting eye but your glasses position as well.

-Just how your eyes are working that day. Fatigued/scratchy/focusing differently all of us glasses wearers do fight with this stuff more then we realize then most folks with 20/20 vision

At the end of the day it can be a real challenge shooting for precision with glasses and irons even more so with glasses. I realize air to powder is different but the fundamentals remain.

[cslinger]

For example. Same rifle, same ammo, same sights, same target, same day, same pretty much everything. One group where I was able to get my focus on vs another where I just kept having focus issues and I can trace all of this to how my vision is perceiving the target. Its challenging and fun but boy would I prefer 20/20 vision. Alas whatryagonnado.

Like alot of us one day I know I will have to bow down and likely go mostly optics.





Take care, shoot safe,
Chris

[veprdude]

I do this sometimes while driving and trying to read road signs. If you pinch your index finger to your thumb and put both hands together to make a very small diamond, you can see better also. It has to be well lit for this to work.

[bamaranger]

A Garand a (30'06) on an INDOOR range. Bet that was just a bit loud.

[Picher]

When you look through the "aperture" created by your thumbs and index fingers, you're reducing the effective diameter of the image seen by eliminating more dispersed light waves, making the image more "pure", so the observed image is "clearer" to you. You can do the same thing by inserting a smaller-diameter aperture in a receiver sight. However, the image becomes somewhat dimmer. That's why we're tempted to unscrew the removable aperture in a receiver sight when the light is low, using just the larger aperture "socket". We sacrifice sharpness for increased brightness, considered a necessity in dimmer light. However, accuracy isn't greatly diminished, since the eye automatically centers when looking through a hole.

[Blue1]

This is like closing a camera lens down to a higher (numerical) F stop, depth of field grows larger with the smaller aperture.

[darkgael]

Try a set of Knobloch or Champion shooting frames…..adjustable in just about every way you can conceive. Add on what you need….occluders, centering devices, plano or Rx lenses, even adjustments for how the device can be fitted to the nose, adjustable irises.

[berettaprofessor]

I do this sometimes while driving and trying to read road signs. If you pinch your index finger to your thumb and put both hands together to make a very small diamond, you can see better also.

I used to do this in the 7th grade to see things better on the chalkboard. Then in the 8th grade I got glasses and didn't need to anymore. I suggest you have your vision examined by an expert.

[Picher]

Some opticians specialize in making glasses for shooters, because we want to see our best at places in the lens that aren't the same as for normal viewing. They can make special glasses that have the best view in the upper left portion of the lens, where we naturally look when shooting.

[Bob Willman]

I use stick-on bifocals during hunting season or serious target shooting. They are available in different diopters, are flexible, can be cut to size and shape and applied wet. They stay in place when dry, peel off easily and can be reused. Amazon at $20 -$25.

NRA Benefactor Golden Eagle Looking forward to Indianapolis

[veprdude]

Originally Posted by berettaprofessor

I used to do this in the 7th grade to see things better on the chalkboard. Then in the 8th grade I got glasses and didn't need to anymore. I suggest you have your vision examined by an expert.

I got LASIK back in 2015. Went from 20/10 with glasses to 20/20 post-LASIK eye. It's a trade-off for sure.

[Picher]

I'm fortunate to for my right (master) eye to have minimal distance correction, so there's little distance distortion at the edges of the right lens. I can see quite clearly when looking over the top of my glasses at distance, but not close-up.

My left eye requires more correction for distance, so that vision is quite blurry without my glasses. though close vision is okay for reading without glasses.

[David Todd]

I just saw this post, and it is something I have been having trouble with for several years.
I am a fullbore TR and small bore shooter of over 50 years.
My eyes have changed quite a bit in the last 20 years , to the point were I " just line up all the fuzzy stuff and use the force"
However, the last two months I figured I had better do something about it because I found my distance glasses were less interfering than my bifocals.
I bought a 1.0 X Gehmann clarifier lens for my front sight, and things improved , but I was still getting some big vertical strings 5 MOA at times at 500 and 800 meters.
A friend sold me a used set of Knobloch frames and I spent an hour with my optometrist and explained exactly what I needed , and that my sights are 36" apart.
The very first day I tried them out , I shot a possible 6V's at 500, then came down to 300 meters , and after my initial sight setting , I looked through the sights at the target and realized I could actually see the orange bull
NO KIDDING!
I didn't have a Shotmarker target set up at 300 so I used an ICFRA 300 meter TR target and used a Birchwood Casey shoot'n'see target in its center so it would be easier to see the bullet holes. The bull is 2 3/4" or very close to 1MOA.
Now, it was a bright day, but still I was amazed at just how well and how much of a difference those glasses made!
I shot two bulls and 3V's, then we shut the range down so others could post targets. I then strapped back into the rifle and shot three V's and two bulls.
After that I went back up to 500 and shot 3 bulls and 2 V's before I ran out of ammo.
I haven't shot that well comfortably in many years, all the stress has gone form my shot sequence, and I credit the glasses for it, and am once again shooting better than 96%!

Now, when I am strapped into the gun , my lens when properly set up is way over towards my nose, nothing like where one would think it should be, which surprised me .
David

[David Todd]

Here is what my glasses look like when they are set up for the rifle and how they look when I am looking straight on. This is reversed of course because it is a selfie on my phone!
I strongly suggest tat anyone having sight picture problems to spend the money for a set of frames and a lens set up properly .
Don't forget to tell your optomotrist what you want and if possible , bring your rifle and kit in so they can see exactly what it is you attempting to do!
David

[divil]

So I just discovered what was going on with this issue, and by discovered of course I mean stumbled accidentally over someone else's discovery: https://www.ssusa.org/articles/2016/...he-rear-sight/


After reading that I grabbed a rear sight aperture I had lying around and played around with it, and sure enough I was soon able to reproduce this issue I described originally, where tilting my head downwards causes a horizontal line to slide upwards, revealing a different image underneath. This line is in fact the top of the frame of my glasses, inverted just like the eyebrow in the article.

As I tilt my head down, my eye moves up to look over the top of the frame, and I see the frame moving up from below. The image it reveals is therefore what I see without my glasses. It doesn't happen at all if I push the glasses back against my face.

Now, when this happened at the range that time, the image I saw over the top of my glasses was by far the better, sharper one. Now that I do it at home, I'm not seeing a huge difference in sharpness. So I'm not sure why the no-glasses image was so much better at the range, but there are a lot of variables - lighting, pupil size, glasses needing to be cleaned etc.

Still, the image I saw that day was better than usual so maybe I'm making a mistake by wearing my corrective lenses while shooting. I only have fairly mild astigmatism and there may be circumstances where it's better to wear plain safety glasses.