Went shooting today. All three of my scopes had crosshairs that are curved at the edges. Played with the eyepiece adjustment. It helped some but the problem never went away completely. All of the evil commie pop-cans were killed however.

Can eyeglasses with a stout prescription create or exacerbate parallax?
Are other problems created by light going through the extra set of prescription lenses?
When going for an eye exam, is there anything the eye doctor can do to help?

Thanks
ZM

Zeke,
I wear glasses in between contact changes and everytime I look thru the scopes on my rifles when I am wearing glasses, the crosshairs appear curved. As to whether it affects parallax I cannot tell you. I try to never shoot or hunt with my prescription glasses on.

Paralax is the shift of the aimpoint based upon the angle at which you look through the scope. The curviture of the reticle sounds like the failure of your glasses to correct an astigmatism. If paralax is an issue because the angle at which you look through the scope is extreme (either by eyeglasses or bad geometry), a scope with an adjustable objective can cure the paralax blues.

John

quote:

Originally posted by Big Bore Boar Hunter:
Paralax is the shift of the aimpoint based upon the angle at which you look through the scope. The curviture of the reticle sounds like the failure of your glasses to correct an astigmatism. If paralax is an issue because the angle at which you look through the scope is extreme (either by eyeglasses or bad geometry), a scope with an adjustable objective can cure the paralax blues.

John

The astigmatism is spot on, I have moderate astigmatism. Two of my scopes have an adjustable rear eyepiece which helped quite a bit. My newest scope does not.
The scope worked the best for me is my Nikon Buckmaster 4x40. It did the best as the early morning light got better and it has the least parallax/curved crosshairs. I don't have a problem getting another one for my other hunting rifle.

On my nest trip to SW, I'll start looking into scopes with AO's and see what I can find.


Thanks
ZM

I have a question then if eyeglasses are what cause the reticles in all my scopes to "seem to be curved.
How is the best way to line up a scope when the crosshairs seem to be crooked. just ignore them or what?
No one awnsered the question if a optician can help the problem.

Maybe the Optician caused the problem.
Always advise them that you shoot and what sights you use.
A scope (only)could be taken along for trials.

I have had bad astigmatism,(it's getting better by its self), maybe once I noticed a curved cross hair, but don't have that problem.
Anyway I'm sure it's nothing to do with paralax.
When I was bad a vertical line was very blurry, a mast in the distance looked like 2, many yards apart. Horizontal was normal.

For some reason looking thru bynos or scopes with or without glasses seemed to fix my problem.
Weird.

The astigmatism you have can only be corrected by the optician. By raising or lowering the scope, you might be able to get the axis of the scope inline with the axis of your glasses. If your presciption allows, you can try contacts, they will help (unless using a heavy recoiling rifle). I would discuss with your optician to see how it may be corrected. The good news, it shouldn't affect point of impact at hunting distances. The bad news, it is very difficult to detect a cant.

An adjustable objective will not correct bent lines, only paralax issues (when you cant align your eye with the bore).

quote:

Originally posted by Big Bore Boar Hunter:
The astigmatism you have can only be corrected by the optician. By raising or lowering the scope, you might be able to get the axis of the scope inline with the axis of your glasses. If your presciption allows, you can try contacts, they will help (unless using a heavy recoiling rifle). I would discuss with your optician to see how it may be corrected. The good news, it shouldn't affect point of impact at hunting distances. The bad news, it is very difficult to detect a cant.

An adjustable objective will not correct bent lines, only paralax issues (when you cant align your eye with the bore).

Last night while installing a new stock on the Howaby I did a little impromptu testing.
I discovered that the postion of my prescription eyeglass lens in relation to the scope has a direct bearing on the amount of crosshair curving. If I look directly through the center of the eyeglass lens, the problem with the crosshairs almost goes away.

I have some money coming back from flexible spending that is going to new glasses. I plan on taking the variable scope in with me and insisting that the new prescription work with riflescopes. I am also considering removing the variable from the Howaby and replacing it with a 6x42 Nikon Monarch. I had almost no issues with a Nikon 4x mounted on another gun. Seems variables cause more issues than fixed power scopes.

Thanks
ZM

Straight lines appearing curved at the edges of the field of view is caused by the magnification not being the same over the entire field of view...Not by astigmatism. Astigmatism is a focusing problem NOT a distortion problem.

Astigmatism is a condition where a lens (or your eye) is incapable of focusing clearly at the same time on lines running at different angles to each other.

If you have astigmatism present one of your cross hairs (either vertical or horizontal) would be in focus and the other would not be.

Obviously your eye glasses are causing the magnification to differ at the edges of the field of view. Try a more square on head position and see if things improve. Most natural shooting positions will have your eye glasses at some amount of angle to the ocular lens of your scope which could cause the distortion of the cross hairs you are seeing since your eye glasses are in effect another lens in the sytem.

When I asked my eye doc whether I should shoot with or without my glasses (and while using binocs) he asked me a rhetorical question: If you aren't gonna wear the glasses why are you buying them? Then he explained that the scope or binocs could only adjust for focal length, and not axis and astigmatism, etc. That was why he recommended you wear your glasses, especially if you have lots of correction.

Scope manufacturers take great pains to assure that all the lenses in the scope are square to each other. Your eye glasses are, in fact, another lens added to the system and it’s really difficult to place your head so your glasses are precisely square to the ocular lens. Having your glasses at an angle to the scope can make some of the light waves bend differently which can cause some amount of distortion in the image you see.

Obviously the degree of angle, the quality of your glasses and your particular prescription all play a part in this.

quote:

Originally posted by dustoffer:
rhetorical question: If you aren't gonna wear the glasses why are you buying them? .

These guys annoy me. They're in their own little world.
Eg. I first got glasses to see clay targets better. Did I need perfect eyesight all the time? NO.

Then at age 46 the Aviation authorities wanted me checked over to the enth degree.
All ready got glasses I told the eyeman.
But how do you read with them he says.
I takes 'em off don't I.

So I end up with bifocals.
But do I fly all the time? NO
So why wear uncomfortable glasses all the time?

Then the eye man talks me into light sensitive lenses for all round use. After I get a few (spares and all) the aviat. auth. lads then say they're no good because they take too long to change if things go dull suddenly.

At 62 now, still don't wear glasses for driving/living, and they're a real pain with iron sights.
And no matter what is said, I NEVER need glasses once I've focused a scope or binocks, I just use them for shooting with scopes for eye protection mostly.

So take Doctors recommendations with a grain of salt. (Unless they want to walk a mile in our shoes.)

quote:

Originally posted by Rick 0311:
Scope manufacturers take great pains to assure that all the lenses in the scope are square to each other. Your eye glasses are, in fact, another lens added to the system and it’s really difficult to place your head so your glasses are precisely square to the ocular lens. Having your glasses at an angle to the scope can make some of the light waves bend differently which can cause some amount of distortion in the image you see.

Obviously the degree of angle, the quality of your glasses and your particular prescription all play a part in this.

This is probably more true to the cause. If the scope is off axis from the the glasses, it can cause lines ot curve. Most folks with asitgmatisms will have trouble with horizontal and vertical lines when they first get glasses. Not knowing the true cause for this, my guess is that the brain is used to seeing multiple image points on the retina and merging them to perceive a straight line. Once glasses are put on, it still thinks one of the images should be straight (the one that is no longer there).

At any rate, if an astigmatism is nstill present, you will have off and on problems looking through lenses of varying types. checking with the optometrist is the best bet.

John

Big Bore Boar Hunter is very correct. Our eyes and our brains will attempt to “fix†distortions in our vision. Anyone who gets new glasses will notice that it takes awhile before our eyes/brain “adjust“ to them.

My last set of reading glasses made parallel vertical lines appear to taper downward, and that lasted for about a week or so before my eyes and brain adjusted to it and straightend the lines out.

UPDATE:

Thanks for all you insight. I think I have a solution.

The eye doctor is a hunter and shooter. He gets it.

The problem is in my glasses. My prescription is such that if I look through the scope dead on, the crosshairs are fine. If I hold my head steady and use my eyes only to focus on an object up or down and use the edge of the len any object, like crosshairs for example, seem distorted. Since my head is slightly cocked when shooting, I am looking a part of the lens that causes distortion.

He suggested contact lenses. He picked out a set he thinks will work well when shooting. I have them on now. In the 25 years that I have wore glasses I have never used contacts until now. Takes a bit of getting used too.

I hope this contact lens thing works. I am tired of wearing glasses. There is a trade off with contacts. I lost most of my up close vision. These contacts need to be just a bit stronger. He is willing to work with me to sort this out.

The crosshairs are nice and straight now. Life is good.

Thanks Again
ZM

Years ago I had a friend with a scope that he just couldn’t hit with. Several of us tried it out and had the same problems with distorted lines, etc. Come to find out the objective lens was very slightly tilted off axis and was causing the same problems your “tilted†eye glasses were causing.

When I get done loading up on caffene and reading the paper I'll be going up on the hill with a few rifles to see how the contacts work while shooting.

ZM

For the opticiens out there, wouldn't it be possible to have ground a lens for eye correction that is simply screwed into the ocular eyepiece of the scope? Obviously you would have to take off your glasses when using the scope but all the correctable problems would be solved, would they not?

Wink,

All lenses are designed to focus light rays at some predetermined distance behind the lens. Eye glasses obviously have a far shorter “eye relief†than do rifle scopes...unless you have an extremely long nose!

Wink Sir, I believe they already have such a thing used in the rear peep on target rifles.
These sights already had positions for tinted lenses, so it was no trouble to use correction inserts. So scopes would be a problem re fitting, but I thought that the scope's own focus would take care of most problems.

Anyway specks are useful as an eye guard anyway, and useful to spot game when not peering thru the scope.

JAL, the eyepiece of the new Leupolds, for instance, is threaded. In my case correction wouldn't just cover any focusing need but also my astigmatism. When one looks through one's own eyeglasses the optical center has been placed where you are looking when looking straight ahead. If you look to the side or towards the edges of the lenses you get distortion and this is what happens when I look through my eyeglasses with a shouldered scoped rifle.

I have used eyeglasses from 16 years and up and this thought have never even occurred to me. So it seems that I am happily unaware of the eventual problem. So in short, I have never experienced any problems with eyeglasses and scopes.

Eyeglasses do not at all have a shorter eye relief than riflescopes.

http://dictionary.reference.com/search?q=diopter

A 1 diopter lens will focus light rays at 1 meter. A 2 diopter lens will focus light rays at 1/2 meter, and a 3 diopter lens will focus rays at 1/3 of a meter. 3 diopter eyeglasses are pretty strong, yet won't converge light rays until a much further distance than a riflescope. Then, that is not the purpose of them anyway.

Your eyes aren't focusing the image on your retina. By giving an assist in bending the light rays appropriately, it helps your eyes manage a focused image on the retina to see clearly.

I don't see why the appropriate lens couldn't be mounted on the scope rather than your eye.

quote:

Originally posted by Esldude:
Eyeglasses do not at all have a shorter eye relief than riflescopes.

http://dictionary.reference.com/search?q=diopter

A 1 diopter lens will focus light rays at 1 meter. A 2 diopter lens will focus light rays at 1/2 meter, and a 3 diopter lens will focus rays at 1/3 of a meter. 3 diopter eyeglasses are pretty strong, yet won't converge light rays until a much further distance than a riflescope. Then, that is not the purpose of them anyway.

Your eyes aren't focusing the image on your retina. By giving an assist in bending the light rays appropriately, it helps your eyes manage a focused image on the retina to see clearly.

I don't see why the appropriate lens couldn't be mounted on the scope rather than your eye.

You’re right. Theoretically, you could probably have any prescription you wanted built into a rifle scope but I’m not sure if it is as simple as screwing a lens onto the ocular bell. Just so happens I’m visiting my eye doctor today to get a new pair of reading glasses and I’ll ask him.

So far, contacts have solved all of the problems I had with scopes. Crosshairs are nice and straight.

I've had glass hanging off my face for 25 years. This is a nice change.

ZM

Well, what did the eyeball doctor say when you went there Rick?
I've picked up on a problem with my latest pair of glasses that I've never had before (no change in prescription, just new glasses and lenses).
For starters, I have a massive astigmatism, can't stand wearing contacts and laser surgery has been ruled out by the doctors. When a rifle is shouldered for shooting through a scope I've noticed that I actually look through the top right corner of the eyeglass' right lens. My latest pair of glasses actually distorts the image through this part of the lens. I never noticed any problem with previous pairs of eye-goggles.
The next time I head into the optometrist I'm going to make sure this problem is corrected by bringing in my old pair of glasses and the ones I am currently wearing. I am going to venture a guess that the lenses I am wearing are not curved properly to my eye at this top right corner.
Does anybody know if I'm on the right track?

Later,

Ross

"When a rifle is shouldered for shooting through a scope I've noticed that I actually look through the top right corner of the eyeglass' right lens. My latest pair of glasses actually distorts the image through this part of the lens. I never noticed any problem with previous pairs of eye-goggles."

Ross,
I would venture a guess that the optical center of the glass is not in the middle of the lens.
At one time I used to use Decot Hy Wyde and Zeiss glasses with the optical center moved as close as possible to the corner of the glasses that I looked thru. I was shooting hipower rifle matches, and the glasses worked great at the time, but I had to take them off as soon as I was finished shooting as I would get a headache if I tried to wear them afterwards.

quote:

Originally posted by R.P.:
Well, what did the eyeball doctor say when you went there Rick?
I've picked up on a problem with my latest pair of glasses that I've never had before (no change in prescription, just new glasses and lenses).
For starters, I have a massive astigmatism, can't stand wearing contacts and laser surgery has been ruled out by the doctors. When a rifle is shouldered for shooting through a scope I've noticed that I actually look through the top right corner of the eyeglass' right lens. My latest pair of glasses actually distorts the image through this part of the lens. I never noticed any problem with previous pairs of eye-goggles.
The next time I head into the optometrist I'm going to make sure this problem is corrected by bringing in my old pair of glasses and the ones I am currently wearing. I am going to venture a guess that the lenses I am wearing are not curved properly to my eye at this top right corner.
Does anybody know if I'm on the right track?

Later,

Ross

My eye doctor said he believed you could have just about any prescription adapted into/onto a rifle scope.Price is another matter, but he didn’t see why it wouldn’t be possible.

I think your logic is dead on the money. What you are experiencing is more than likely caused by the angle of your viewing. The more “square†the scope and your glasses are to each other the less the problem shows up...right?

This may sound silly, but you might give it a try. Tape a piece of paper with a hole in the center over the right lens of your glasses and adjust your shooting position accordingly and see what happens. You can experiment with different sized holes and see if it helps. You may need a longer LOP to square you head more to the scope. Just a few thoughts to try out before you invest in expensive screw on lenses.

Rick,
I thought I might be on the right track. I really have no intention of adding anything to a scope and have tried to adjust my head to the scope and for a better alignment to the optical center of the eyeglass lens. It does clear up when I try it but it (holding my head to the rifle that way) feels very unnatural to do so. I still plan on taking both glasses in to where I got my previous pair of glasses to help me explain and have the doc, or whomever specializes in that stuff, figure it out. I can still shoot well enough for prairie dogs at 250. It just boils down to having one less noticeable item on my mind when I'm aiming. I'll repost when I find something out from them.

Thanks guys,

Ross

Ross,

Lens manufacturers (eyes glasses, camera lenses, rifle scopes, whatever) go to great lengths to remove as much spherical aberration and distortion across the entire lens surface as they possibly can. This ain’t easy to do since lenses are not flat, and that is one reason that higher end optics cost more money.

Another trick you might try (it doesn’t cost anything!) is the same thing you do to adjust for parallax on the fly. Move your head slightly to the rear and you will be forced to center your eye directly along the lens axis.