Shortsighted ... Time for glasses

[johngarnett]

Shugie

Varifocals are really only good for general purpose use. Specific uses ie shooting, diy, 'computering' and some sports are best catered for with specific spex. Try varifocals through a scope and you will get all sorts of distortion.

If you look at someone else shooting, who is wearing spex, you will see that the part of the lens used is, for a RH shooter, the upper left corner of the right lens, by the bridge of the nose. To get best vision the optical centre of the lens should be 'decentred' to that point to get the best optical correction.

You can have shooting spex made specially for this or you can tweek and modify a spare pair to achieve this. Have a play at moving the spex around whilst viewing through the scope. Single vision will be kindest!

If you have difficulties perhaps visit an optometrist with an interest in shooting.

JohnG

[shugie]

Shugie

Varifocals are really only good for general purpose use. Specific uses ie shooting, diy, 'computering' and some sports are best catered for with specific spex. Try varifocals through a scope and you will get all sorts of distortion.

If you look at someone else shooting, who is wearing spex, you will see that the part of the lens used is, for a RH shooter, the upper left corner of the right lens, by the bridge of the nose. To get best vision the optical centre of the lens should be 'decentred' to that point to get the best optical correction.

You can have shooting spex made specially for this or you can tweek and modify a spare pair to achieve this. Have a play at moving the spex around whilst viewing through the scope. Single vision will be kindest!

If you have difficulties perhaps visit an optometrist with an interest in shooting.

JohnG

I did try the chap at Bisley for some clays glasses, he made up some Zenith wrap round type glasses which were really excellent but for the fact there was a lot of off axis distortion, so if I looked at something through the part of the lens in the area you described it was nowhere near as clear as the centre was. It seems my astigmatism causes problems even with single vision (RH +4.75 -3.00 at 40 axis). We gave up in the end, as he couldn't get a wide field of vision in decent focus.

But having just fiddled about with a spare scope, I can see what you mean about which part of the lens needs to be the optical centre, I wonder if my present optician can cope with that!

[FredB]

If you are getting short sighted and want to shoot with iron sights, then you need do nothing! Given the choice of being able to focus on the target or the front sight, plus the daylight around it, then choose the front sight every time.
Fred

[johngarnett]

Shugie,

I fear with that prescription you will get off axis distortion!

A shooting spec which is completely adjustable with a small, approx 1" dia, lens may give you best optical performance when you are prone, in the shooting position. Gehmann and Champion makes spring to mind. You can use the R lens for aiming and have a reading lens in the L for doing you score diagram.

Good luck

JohnG

[shugie]

Shugie,

I fear with that prescription you will get off axis distortion!

A shooting spec which is completely adjustable with a small, approx 1" dia, lens may give you best optical performance when you are prone, in the shooting position. Gehmann and Champion makes spring to mind. You can use the R lens for aiming and have a reading lens in the L for doing you score diagram.

Good luck

JohnG

I wish I'd known about the limitations of my prescription before, it would have saved me much money! My left eye vision is very poor, so I can't read with it, with or without a lens. Oddly though binocular vision is better than my prescription suggests, but that is of no use shooting a rifle.

I'll look into your suggestions of a small lens, the best pair of single vision glasses I've ever had were quite small lenses. Do you think the index of the lens material makes the off axis distortion worse, it seems that the thinner the lens the worse my problem?

All help and suggestions welcome!

[Steve E]

Shugie
Get your self a specific set of shooting glasses with a small (18mm) lens for the right eye and a larger lens for the left eye. I can recommend going to Specsavers in Newbury and booking a double appointment with Gary Alexander. He is shooter so will be able to sort you out. It may not be expensive as you think.

[johngarnett]

Refractive index dictates the thickness of a given lens power. Higher refractive index = thinner lens = more chromatic aberration (colouring on edges). Thinner lenses should reduce the possibility of distortion 'cos there is less material to look through.

There is a lens form (design) called 'aspherical' which gives the best of flatness, thinness and minimises aberrations (distortions). There is also the new 'freeform' or 'digital' single vision lenses which are computer designed to a set of measuements taken by your optom. These give you the best out there. But they have to be dispensed and fitted properly otherwise they're less than useless and you become non tolerant of them.

I would say none of these are the Holy Grail for shooting though!!

One of the most important atributes of an optician is 'Time'. You, the patient, should be given time to explain your problems/difficulties and the optician should take time to explain the options available to ease those problems optically or otherwise. Unfortunately, Time is often not available as the commercial aspect says 'bums on seats asap'. But stand your ground. You pay enough, you should be given Time. Particularly when it's as fiddley as shooting corrections.

SteveE. My suggestion too. There is also Mike Taylor in Teignmouth/Dawlish area. (I know it's a long way but it's a lovely area!)

JohnG

[shugie]

Thanks for all the information. I've spent hours arguing with opticians to get my expensive varifocals to my liking, I get the impression that they know exactly what the problem is but don#t want to let on. Yet they've always accepted that I can't get on with some lenses and refund me, but it takes lots of time, mine and theirs.

So far the best varifocals were some Rodenstock ILT, brilliant but when my reading prescription went up by .5 they could never make me another pair that were anywhere near as good, currently on Hoylalux ID with a need on the way to increase the reading power in those too.

I'll try the chap in Newbury, I remembered you mentioned him before Steve. My experience with Specsavers is that you rarely see the same person twice, and that they are somewhat reluctant to admit to mistakes. Hopefully having a named contact will get round that.

Yes Teignmouth is a lovely part of the country, but it's too far for something that on previous experience can involve several visits.

[Alpha1]

They sound like Vocational Varifocals. Very good lenses. I live in mine in the Cave and my 'pc suite'. The only problem I ever found at work was patients resistance to cost. By the time you have 'real' varifocals, vocationals, sunspex and single vision distance as spare/driving the cost mounts up. But all have their place!

If they are suggested to anyone - consider them. They do work but don't expect them to be general purpose.

JohnG

They were expensive but they are worth every penny. I would not be with out them.

[zzr1100]

Well it turns out that I'm not that shortsighted after all ... I do however have astygmatism (sp) in both eyes .. Apparently would not have been helping at all ...
Glasses on the way !!