Rear Aperture Sights and Astigmatism

[dhagerty40]

I think you got confused. The Gehmann 510 is not a sight but an iris only. to use this, you would need a thread adapter for your redfield sights which gehmann makes. The 530 is the 510 with a 1.5x magnifier.

I went through the same problem you are having and it drove me crazy. The Iris helped a lot. I will send another post which explains how it works.

Now, instead of using the 510, you might want to look at this that attaches to your glasses. Since I shot a lot of guns with notch and post type sights, this is what i used.

Gehmann Iris - Disc for Regular Glasses | Champion's Choice

 

[Bennybooboo]

It's great to be free of the constraints of rules, isn't it?!?!

To solve your problem, I would suggest consulting the Heinz Reinkemeier YouTube Videos regarding sights and sighting. Each adjustment has an intended function and will yield specific changes. Similar to the depth-of-field adjustment on a camera... sure it acts as a zoom-in/out, but that's not the correct use of the adjustment.

Further reading can be found in Ways of the Rifle (long discontinued) and it's current replacement Olympic Rifle Shooting. At least one of these texts should be in every rifleman's library, regardless of discipline.

Make time on the firing line (preferably at a shooting bench with rifle support) and make educated sight adjustments while noting the result. Similar to going to the optometrist who is asking "Better at 1 or 2?" in a specific sequence. This time is absolutely a worth while investment.

Really, it's wonderful to be on the firing line and able to make sight adjustments correctly the first time as needed. Similar to a photographer shooting in Manual Mode with confidence.

 

[dhagerty40]

and here is the explanation:

The human eye, whether or not prescription glasses are required, cannot focus on both sights and the target at the same time. The eye will constantly shift focus from the sights to the target trying to ensure proper alignment. Unfortunately, as we age, the eye loses the flexibility which allows it to do this; thus, sights and target begin to grow fuzzy. There is a simple way to combat this by increasing your eyes' depth of field (range of focus). If you look through an aperture or pinhole of the correct size, you will be able to see both sights clearly, and the target will be clearly defined as well. It was utilizing the principle of a pinhole that allowed the original box camera to work without a lens, and its pictures were in clear focus from about 2 feet out to infinity. To check out this phenomena for yourself, try this rough, but inexpensive, experiment:

1. Make a fist, put it up to your shooting eye, and look through the tunnel formed by your fingers. By manipulating your fingers, you can adjust the size of the hole.
2. Hold a pencil out at arm's length; the point represents your front sight. Pick out a distant object to be the target.
3. Sight through your fist, adjust the hole to the right size, and you will be able to focus on both objects near and far.

 

[TuckerJ]

Again my terminology slip has added confusion. I shouldn't have called the Gehmann 510 a sight. I have Redfield Olympic sights with the stock fixed "disk" aperture. I'm looking to replace this with either an adjustable iris, or possibly an adjustable iris that also has some +/- vision correction abilities also.

I have no need to replace the "sight."

 

[68Hoyt]

Iirc , the “Gehman” instructions say the 530 is NOT for use with astigmatism
Do any of you think a front sight magnification lens would help TukerJ?
I am trying to learn as well

 

[SteveUrban]

Again my terminology slip has added confusion. I shouldn't have called the Gehmann 510 a sight. I have Redfield Olympic sights with the stock fixed "disk" aperture. I'm looking to replace this with either an adjustable iris, or possibly an adjustable iris that also has some +/- vision correction abilities also.

I have no need to replace the "sight."

One thing that you can look at is a lens called “ Eagle Eye”. I don’t think it will work with the Redfield, but it does work with the Gehmann. It is a small magnifying glass that fits in the front sight to magnify the bull.

Cheers,
Steve

 

[Tim Slater]

Iirc , the “Gehman” instructions say the 530 is NOT for use with astigmatism
Do any of you think a front sight magnification lens would help TukerJ?
I am trying to learn as well

Maybe. A slightly larger fuzzy blob might be easier to aim at.

My optician, himself a competent small ore shooter, recommended an Eagle eye for short-sighted shooters to compensate for the negative lens.

That said, I think correcting astigmatism and distance would be the first steps. These don't need to be in the same lens/gadget though.