Glasses and scope problem

[Andy Cross]

Variable humans

As an optical engineer who has worked in an ophthalmic section and with ophthalmologists I can tell you that the optimum setting you seek for reticle focus and parallax will change from day to day or even from hour to hour especially when you have reached an age over 40.

Sometimes reticle focus cannot be achieved because the correction you need is outside the range offered in the scope. It is also only spherical adjustment so if you have an astigmatism over 2 diopters the sharp focus of the reticle on both planes will be difficult if not impossible. Toric lens elements an be made to achieve this but very expensive.

The rediced flexibility of the eyes lens as we ago may also not be responsive enough to go from focusing on the areial image the scope produces of the target to the reticle quickly enough to see both in focus even if the parallax adjustment is set optimally.

I know a couple of shooters who have retired from the sport in recent years because of these issues. People suffering from myopia will find it easier to deal with than those suffering from presbyopia and or astigmatic issues.
Andy.

 

[Mike Bryant]

This has nothing to do with clarity only size. A focused reticle is a focused reticle at 2X or 50X. We might want to consider the fact that any other additional lens in the system, while adding to image size, degrades image quality.

The company that designed it made it for people who couldn't get the reticle focused. It wasn't made to boost the image though it does do that to a certain extent. The company that makes this had an employee that they had a rifle built for him to honor him as a long time employee. He looked through the scope and wasn't able to see a reticle no matter how they had it adjusted. So, they built an adapter ground to where the reticle was clear for the elderly gentleman. The 2.5x, 3x and 4x they offer is for vision requirements not scope boost. It won't hurt to call them and ask about it. You'll find the same thing I did.

 

[Chism G]

As an optical engineer who has worked in an ophthalmic section and with ophthalmologists I can tell you that the optimum setting you seek for reticle focus and parallax will change from day to day or even from hour to hour especially when you have reached an age over 40.

Sometimes reticle focus cannot be achieved because the correction you need is outside the range offered in the scope. It is also only spherical adjustment so if you have an astigmatism over 2 diopters the sharp focus of the reticle on both planes will be difficult if not impossible. Toric lens elements an be made to achieve this but very expensive.

The rediced flexibility of the eyes lens as we ago may also not be responsive enough to go from focusing on the areial image the scope produces of the target to the reticle quickly enough to see both in focus even if the parallax adjustment is set optimally.

I know a couple of shooters who have retired from the sport in recent years because of these issues. People suffering from myopia will find it easier to deal with than those suffering from presbyopia and or astigmatic issues.
Andy.

Good post Andy.

It was enlightening to me to find that I have an eye problem that cannot be fixed by my high dollar riflescope. It was worth a trip to the Ophthalmologist.


Glenn

 

[gabe ledesma]

Thanks for all the Good info guys. I am up for a new pair of glasses . I will talk with my Ophthalmologist and see if he can find a certain typ of glasses that i can use with my riflescope that work better than what i got. Gabe

 

[Jo Gris]

The best part of that long article that someone publised years ago on properly focusing a scope and is often sited here as the Holy Grail is the sentence in which he says "This is where the Booger falls into the soup". I use that one sometimes and think it is the only valuable thing I derived from the entire article. As was pointed out by Andy and some others, there is a lot more at play here than meets the eye, pun intended. Apparently a lot of things folks believed to be absolutes are not.

 

[laver]

Andy,

Would lens replacement surgery help correct this vision defect as it relates to shooting. I may have lens replacement surgery in my future, anyway.

Larry

 

[Andy Cross]

May be may be not

When I was working in ophthalmic optics there were several types of lens replacements I made. But the one thing they all had in common was that they were of a fixed focal length. The lens in the human eye isn't. Its curvature is changed via the ciliary mussels to accomodate where you want to focus. Less curvature for distance more for near etc.

It's a common practice to get a replacement lens for distance and use corrective lenses for near. If an astigmatism is involved then the correction is made with corrective lenses. I have never made a replacement lens with a toric surface. So depending on how large the correction difference is between your near and distance vision it may only help with one. A flat field bifocal - which would give maximum eye relief from the scope - with no power in the distance combined with a suitable size, shape and positioned add or segment for near might work.
Andy.

 

[tim]

The company that designed it made it for people who couldn't get the reticle focused. It wasn't made to boost the image though it does do that to a certain extent. The company that makes this had an employee that they had a rifle built for him to honor him as a long time employee. He looked through the scope and wasn't able to see a reticle no matter how they had it adjusted. So, they built an adapter ground to where the reticle was clear for the elderly gentleman. The 2.5x, 3x and 4x they offer is for vision requirements not scope boost. It won't hurt to call them and ask about it. You'll find the same thing I did.

You initially refered to it as a "booster" not me. My only point is that bigger is just that, not clearer/sharper. The other point that I suspect Andy would agree with is that when I was into photography I learned any additional lens is more glass, whatever else it does it degrades image quality

 

[tim]

As an optical engineer who has worked in an ophthalmic section and with ophthalmologists I can tell you that the optimum setting you seek for reticle focus and parallax will change from day to day or even from hour to hour especially when you have reached an age over 40.

Sometimes reticle focus cannot be achieved because the correction you need is outside the range offered in the scope. It is also only spherical adjustment so if you have an astigmatism over 2 diopters the sharp focus of the reticle on both planes will be difficult if not impossible. Toric lens elements an be made to achieve this but very expensive.

The rediced flexibility of the eyes lens as we ago may also not be responsive enough to go from focusing on the areial image the scope produces of the target to the reticle quickly enough to see both in focus even if the parallax adjustment is set optimally.

I know a couple of shooters who have retired from the sport in recent years because of these issues. People suffering from myopia will find it easier to deal with than those suffering from presbyopia and or astigmatic issues.
Andy.

No doubt why, I guess, as I get older that eyepiece gets closer to the end of the threads on the tube. Hey Andy is there any such animal as a center of focus change on eyepieces? On the .22BR sporters we shoot at 50, several of us that shoot Leupold LRT variables sent them back to change the side focus to a "center of focus" at 50 rather than 100. Big help for parallax settings.

 

[Boyd Allen]

If you are progressively screwing the eyepiece out, so that the scope is getting slightly longer, one thing to consider, especially if recoil and eye relief are not major issues are the lenses that are sold as power boosters. You may not need the power, but they require that the eyepiece be focused a couple of full turns or more forward of where you would without them. I am using a home made version, that I managed to figure out for myself, and for a +2 diopter I have to turn the eyepiece of my B&L over two turns farther forward than when the lens is not on the scope, I also get enough of a clear sharp power boost so that my 36X looks very much like a 45X only it is no darker, and its field of view is unchanged. Short version, I see better with it than without. I should add that the eye relief is about 1/2" shorter.

 

[Del Martin]

With regard to the human variables changing from day to day I have noticed that blood pressure seems to have an effect on reticle focus. Has anyone else noticed this?

 

[gabe ledesma]

With regard to the human variables changing from day to day I have noticed that blood pressure seems to have an effect on reticle focus. Has anyone else noticed this?

Not realy,but i have noticed that my blood preasure does go up when i shoot 4 in a bug hole and my 5th shot is out. Any body els feel that?

 

[tim]

With regard to the human variables changing from day to day I have noticed that blood pressure seems to have an effect on reticle focus. Has anyone else noticed this?

Not for some time. I can't find a nurse willing to stand there with the cuff while I shoot.

 

[Andy Cross]

More glass

You initially refered to it as a "booster" not me. My only point is that bigger is just that, not clearer/sharper. The other point that I suspect Andy would agree with is that when I was into photography I learned any additional lens is more glass, whatever else it does it degrades image quality

Yep. Every additional lens element absorbe more light. But another point some may not be aware of is that the boosters need to have their optical centres aligned with the optical centrecof the scope or a prismatic decentration effect will result. More the boost more the shift.
Andy

 

[Andy Cross]

Don't know of one but

No doubt why, I guess, as I get older that eyepiece gets closer to the end of the threads on the tube. Hey Andy is there any such animal as a center of focus change on eyepieces? On the .22BR sporters we shoot at 50, several of us that shoot Leupold LRT variables sent them back to change the side focus to a "center of focus" at 50 rather than 100. Big help for parallax settings.

I haven't heard of any company that makes one but that doesn't mean one couldn't be made. The steps you would need to follow are get exact correction values for your eyes for distance and near. If astigmatism is present the principle powers for each meridian would be required along with the axis.

The go to an optical engineering Co and have them draw up a schematic. Have the elements ground and the device prototyped. Refine then trouble shoot. Usually better to have it integrated rather than attached as an add on. But I bet you wouldn't like the price.
Andy.

 

[abintx]

With regard to the human variables changing from day to day I have noticed that blood pressure seems to have an effect on reticle focus. Has anyone else noticed this?

Yes. I don't have high blood pressure, but I do know that high blood sugar levels, dry eyes and allergies can and does have an effect on the cornea.

The eyes have been described as windows to the body and conditions that affect your body may affect your eyes as well. Also, the medications you take can have an impact on your vision and eye comfort.

 

[Boyd Allen]

Because I had the same doubts about using an axillary lens on a scope's eyepiece, and was not willing to do an expensive experiment to find out if that was the case, I held off on trying one, and eventually was able to discover the nature of the lenses that are used for this purpose, locate and alternate, much cheaper source, and try one. Now I have two such lenses, from my alternate source, on my 36X B&L scopes. I can tell you from personal experience that these lenses, on my particular scopes, considerably improve my view of the target. Sometimes it is better to withhold judgment until you have actually experienced something. I too have a photographic background, and opted for a Micro Nikkor over screw in close up lenses, back in my film photography days. If a scope had marginal optics, it may be that further magnification would indeed look ugly. Fortunately in my case, this was not a problem.

 

[Andy Cross]

Alignment

The types of booster I have seen have all used a slip over the eye piece of the scope fixture. Usually a non compound sometimes coated lens element assembled in a soft neoprene / silicone cup. I can't see how proper alignment coukd be achieved using a method of attachment like this. I have made several boosters that were installed between the end of the scope and eye piece but that's an entirely different kettle of fish.
Andy

 

[Mike Bryant]

The Bulls Eye Pro lens screws into the rear lens cover threads on the Leupold competition series scope. When I talked to the owner, he said the coated lens had 97% light transmission. So, it would lose some light transmission. When I put the 2.5 unit on the 45X scope that I have, the eyepiece had to be moved forward quite a few turns to focus the reticle from where it was without it. I know nothing about optical engineering. I'll see what I think of it when I get a chance to put it on a rifle and shoot it.