Quick question, irises and diopters

keithwwalker · Post by **keithwwalker** » Wed Sep 15, 2010 12:41 pm

Is it possible for an iris to have a corrective vision diopter in competitive ISSF 10m air rifle?

Second, does it make more sense to have the diopter in the iris/rear sight, than just to have prescription shooting glasses?

I would think that with shooting glasses, there may be the potential for more refraction error...

justadude · Post by **justadude** » Wed Sep 15, 2010 1:37 pm

Is it possible for an iris to have a corrective vision diopter in competitive ISSF 10m air rifle?

Short answer NO. Any corrective lenses must be worn by the shooter. ISSF 7.4.1.3.1 and 7.4.1.3.2

Second, does it make more sense to have the diopter in the iris/rear sight, than just to have prescription shooting glasses?

Probably but it is not allowed by the rules so it is an academic discussion.

I would think that with shooting glasses, there may be the potential for more refraction error...

Yes, there is. This is why there are special frames and alignment tools so the shooter can adjust the glasses to look exactly perpendicular throught the center of the lens.

'Dude

keithwwalker · Post by **keithwwalker** » Wed Sep 15, 2010 2:43 pm

thx dude!

JH · Post by JH » Thu Sep 16, 2010 11:13 am

Anschutz does manufacture a lens frame that can be attached to the rear sight, but as 'Dude mentioned, against ISSF rules. So, if shooting matches that aren't shot according to ISSF rules, why not try it? Just check the applicable rules first, though.

Pity though, don’t really know what advantage a corrective lens fixed to the sight would give you over someone with perfect eyes. Having poorer eyesight already disadvantages you, then add a shooting frame with even more complexities. I don't know anyone with perfect eyesight that has to live with the complexities of shooting glasses. But, hey, the rules are the rules. Perhaps someone can explain why the lens must be worn by the shooter? I would find it very interesting to know the reason.

(PS If I changed this to an academic discussion, I apologise. I'm just curious by nature. :) )

JH

justadude · Post by **justadude** » Thu Sep 16, 2010 11:37 am

One potential issue with allowing magnification lenses to be attached to the rifle is the ability to build a low power telescope out of the system. Now, this would not be a trivial project but a simple lens in the front sight and then in the rear sight or on the shooter and it is, at least on paper, a possibility. So then where is the line between a corrective lens and a magnification system and having the technical judges make the determination.

By restricting the lens having to be worn by the shooter it removes all possible doubt.

That's one theory

'Dude

keithwwalker · Post by **keithwwalker** » Thu Sep 16, 2010 2:36 pm

MEC Centra also has diopters in the rear sight, but not the front. I wonder why they sell them if they are illegal in ISSF?

Anyway, I am slightly nearsighted. I can drive a car without my glasses, but a target is too fuzzy beyond 10m.

I guess it forces people who are really competitive to have corrective surgery.

JH wrote:Anschutz does manufacture a lens frame that can be attached to the rear sight, but as 'Dude mentioned, against ISSF rules. So, if shooting matches that aren't shot according to ISSF rules, why not try it? Just check the applicable rules first, though.

Pity though, don’t really know what advantage a corrective lens fixed to the sight would give you over someone with perfect eyes. Having poorer eyesight already disadvantages you, then add a shooting frame with even more complexities. I don't know anyone with perfect eyesight that has to live with the complexities of shooting glasses. But, hey, the rules are the rules. Perhaps someone can explain why the lens must be worn by the shooter? I would find it very interesting to know the reason.

(PS If I changed this to an academic discussion, I apologise. I'm just curious by nature. :) )

JH

David Levene · Post by **David Levene** » Thu Sep 16, 2010 2:40 pm

keithwwalker wrote:MEC Centra also has diopters in the rear sight, but not the front. I wonder why they sell them if they are illegal in ISSF?

Because not everybody shoots under ISSF rules?

FrankD · Post by **FrankD** » Thu Sep 16, 2010 6:59 pm

Dear shooting friends,

in Germany magnification lenses (max. 1,5 magnification) are allowed for senior shooters over 45 years. You can use them in the rear sight or in the front sight. In the front sight we call it Adlerauge, in English eagle eye. For the rear sight there are lens systems with +- 4.5 dioptres and magnification.

In Germany now air rifle and small bore Standing shooting with a rest is very popular. Many older shooters use there a magnification lens.

Best regards from Germany

Frank

JH · Post by JH » Fri Sep 17, 2010 2:19 am

I hear what 'Dude is saying and completely agree. If shooting with peep sights, it would be a disadvantage shooting against someone with magnifications built onto his sights.

However, the magnification can still be achieved (on paper) if the one lens is worn by the shooter. If the one lens is in the front sight and the other on the shooter, the same effect could be achieved than having the other on the rifle. By restricting the lens having to be worn by the shooter how can it remove all possible doubt?

I am attaching pictures of the lens. If looking at this frame and how it is attached, I fail to see how having this specific lens frame on the rifle will give a shooter any advantage over someone with perfect vision.

I have astigmatism in my aiming eye. Started using a shooting frame to correct, but now I have to ensure that my lens is perpendicular through the centre. In my earlier years I did not need to worry about this and, if it wasn’t for the fact that our matches are shot in accordance with ISSF rules, I would have had the Anschutz Monoframe already.

And the fact that I work on a PC for 10 hours a day also doesn't improve my eyesight! ;)

Really enjoying TargetTalk! Don’t really have anyone to discuss things like this here in South Africa.

Happy shooting!
JH

David Levene · Post by **David Levene** » Fri Sep 17, 2010 3:12 am

JH wrote:However, the magnification can still be achieved (on paper) if the one lens is worn by the shooter. If the one lens is in the front sight and the other on the shooter, the same effect could be achieved than having the other on the rifle. By restricting the lens having to be worn by the shooter how can it remove all possible doubt?

I'm not sure what you are suggesting here.

The ISSF rules don't just prohibit lenses in the rear sight, it's in the front sight as well (or anywhere else attached to the rifle).

Guest · Post by **Guest** » Fri Sep 17, 2010 5:29 am

JH wrote:I hear what 'Dude is saying and completely agree. If shooting with peep sights, it would be a disadvantage shooting against someone with magnifications built onto his sights.

As someone who doesn't shoot ISSF, is over 45 and uses an adjustable magnifying diopter as part of my rearsight - I'm not sure this is entirely correct for a single lens. I use it to help me focus on the foresight but the magnification is a mixed blessing.

Here's the rationale:
With magnification in the rearsight the aiming mark appears bigger - or, if you prefer, the aiming mark appears closer.
Unfortunately the foresight also appears bigger/closer, so effectively you are aiming with a reduced/shorter sightbase.
Consequently, any errors that you make in the positioning of your head on the rifle or eye behind the sights will be exaggerated and bad shots due to these errors will be worse.

Which is the reason that I use a 12" extension tube - to get that sightbase back to where it should be.

The Eagle Eye is a different proposition as it makes the aiming mark appear larger but doesn't help you focus on the foresight and doesn't reduce the effective sightbase.

Using an Eagle Eye WITH a magnifying rearsight diopter - I'm not sure whether that's an advantage or not...

Of course I may be wrong.
Ken.

PS. one of my best shoots was under ISSF rules without the diopter but with the tube... go figure.

JH · Post by JH » Sat Sep 18, 2010 8:17 am

Please understand that I do not want to magnify my sight picture, or use any type of magnification in any of my sights what so ever.

My prescription lens is a correcting lens and I just do not understand the ISSF rules regarding correcting lenses. Rule 7.4.1.3.1 states that correcting lenses must not be attached to the rifle. Rule 7.4.1.3.2 states correction glasses may be worn by the shooter. What advantage would there be if the correcting lens is on the rifle instead of on your head?

Roodaddy600 · Post by **Roodaddy600** » Sat Sep 18, 2010 8:48 am

What advantage is there to having a second pocket on your shooting jacket? There isn't. But yet there is a rule stating that you can't have it. So just live with the rule that you can't have a corrective lense attached to the rifle, it's that simple. Do you not have ears so glasses won't stay attached to your head? If thats the case I suggest you use the shooting lense that is attached to a headband.

It sounds like a two year old in here, "can you do this?" no. "why?" because of this rule." "why?" because the governing body made a rule against it. "why?" because that's what they do. "why?" OMG!

mapletune · Post by **mapletune** » Sat Sep 18, 2010 10:18 am

correction attached on the rifle can be adjusted so that it is very very close, even inside the sight system, and always perfectly centered.

However, if lens is worn on the shooter, it is the shooter's responsibility and skill to always adopt the exact same position to minimize refraction errors.

hope that helps.

JH · Post by JH » Sat Sep 18, 2010 11:50 am

Thanks for everybody's insights.

I'm sorry for all the "why"s. I just enjoy the sport and I am the kind of person who loves knowing the reasons behind why things are the way they are. I enjoy knowing how a light bulb makes light, or why the rule says no lens on the rifle, so that one day when another shooter asks me the same question (not that there are many shooters left in RSA) I can tell them of what I learned from experienced shooters from abroad, and not an ignorant answer you give a two year old like "because I say so".

If the answer is then that of Mapletune (thanks!), then I submit that all shooters with corrective lenses are the more skillful shooters, as we shoot the same, if not better, than our peers with perfect vision who do not need to have an extra lens centered every time he/she positions.

Kind regards,
JH

keithwwalker · Post by **keithwwalker** » Sun Sep 19, 2010 3:45 am

So does a shooters lens have any advantage whatsoever over contact lenses?
Can the prescription be more exact?

I am nearsighted, but with age, my sight @ distance is
improving a little, but not enough for 25m shooting.

westerngriz · Post by **westerngriz** » Sun Sep 19, 2010 5:52 am

Well contacts have a tendency to move around. if that happens you wont be looking through the center of the lens. Also your perscription will be slightly different with shooting glasses over your normal eyeglass perscription. USUALLY you want the shooting glass perscription to correct to either +.25 or +.5

justadude · Post by **justadude** » Mon Sep 20, 2010 9:18 am

Roo said,

"why?" because the governing body made a rule against it. "why?" because that's what they do.

While it was originally noted with a bit of sarcasm (at least it looked that way) there is an amazing amount of truth to that. Not just in shooting I have seen governing bodies make some pretty odd regulations seemingly just because they can. Someone decides "Hey this is a problem." and the next thing you know there is a rule that leaves the people whom it affects scratching their heads.

I was introduced to ISSF shooting about 1975, back then ISSF was called the UIT which translated to ISU or International Shooting Union. Even back then if you needed corrective lenses you had to wear them. I never questioned why, it was always just the rule.

From the pragmatic side I can't imagine the issues that would be involved in allowing optical elements in the sight system but they would have to be below some particular magnification or diopter value. Then checking that at tech inspection. I would pity the judges that would have to start checking optical elements at a major tournament... ouch

There are plenty of ISSF rules where you could drive yourself nuts wondering how they came up with that one. Why is a sling allowed to be 40mm in width? Why not 35 or 45mm. I dunno, it just is. Boots, they just are... etc. If you find a real shooting historian you might find they would be able to offer what happened for some of this stuff to be a concern. Won't change anything.

Make your life easier, for some of the rules, don't worry about the why, just accept and put more brain power into shooting tens.

Rules bodies, as Roo said, they make rules. Most of us here are shooters, we should simply concentrate on shooting tens... within the guidlines of the rules.

Just some rambiling philosophy for a Monday morning.

Cheers,
'Dude

JH · Post by JH » Tue Sep 21, 2010 1:58 am

justadude wrote:Roo said,

Rules bodies, as Roo said, they make rules. Most of us here are shooters, we should simply concentrate on shooting tens... within the guidlines of the rules.

Just some rambiling philosophy for a Monday morning.

:)

Agree, no use in fighting the system that has been there from before I was born. I humbly bow to the powers that be.

Quickly scanned through what looks to be an interesting piece of reading on the Knobloch site. Will read it in detail later this evening. For anyone interested, the site address http://www.knobloch-schiessbrillen.de/allframes.html . Click on the 5th tab labeled "Brochure" and then on the link that says "Vision for shooting".

Keith, there is an interesting paragraph about contact lenses on that site as well.

Good shooting!
JH