Iris Shutter and Centering device

Judith Arifandi · Post by **Judith Arifandi** » Thu Dec 22, 2011 12:09 am

I shot AP only and I'm 16.

I saw them on Knobloch website. If they really increase the sharpness, it would be more than helping. I have 1.5 astigmatism for right eye and 3 astigmatism for the left. I am aware that it would not help my score, but if it somehow will make my eyes more comfortable. I think its worth it. So anybody tried it? by the way, what is centering device?

Right now, if the lights isn't at correct amount, The black area turned into egg-shaped. because of this egg-shaped, I need extra focus on sights. if iris shutter can make egg-shaped into solid round, I think I can deal with both sights and target clear at the same time.

and the most importantly, how to use it? I plan to buy it online, and no one in my country use it. I'm really blind about these tool. please if anyone could give me explanation on how these tool works.

John Marchant · Post by **John Marchant** » Thu Dec 22, 2011 2:21 am

The centering device assist you in getting the alignment of the centre of the lens directly in line with the centre of your eye. When you clip the centering device on, if you cannot see the target with your head in your natural comfortable position, then you will need to move the lens holder until you can see perfectly straight through the centre of the small aperture of the device, without any lateral or vertical reflections. This may need the assistance of a fellow shooter to make the final adjustments for you.
Once that you have the centre of the lens and holder aligned, tighten up the adjusting screws and hopefully provided you do not knock the lens holder when packing the frames away, you should not need to make any further adjustments.
The iris helps to adjust the amount of light entering the pupil, thereby maintaining the pupil at a relatively constant size. This should then help to make the foresight appear sharper, when adjusted correctly.
If the target appears egg-shaped, then check to make sure that your astigmatism correction reference datum is exactly aligned in the lens holder.
Do not attempt to focus on both the aiming mark and the foresight.
The foresight is the important part as that is the most likely item that can move and cause misplaced shots. The target is normally stationary.

Judith Arifandi · Post by **Judith Arifandi** » Thu Dec 22, 2011 10:28 pm

thank you for your reply
do you know how to adjust iris shutter? was iris shutter has some kind of screw that could be turned or some thing like that?

btw I'm looking for online shop that sells them with world wide shipment. do you know any?

RobStubbs · Post by **RobStubbs** » Fri Dec 23, 2011 3:59 am

The iris shutter has a simple lever on the side so you can adjust it in position. It has a number of disadvantages and I can't help feeling that a properly made lense would be a better solution. One drwback of the iris is that it can easily be made to get everything in focus, which you don't want. The foresight as John says is the most important so get a lens made to focus on that. The rear sight will be slightly off focus and the target slightly more out of focus.

Rob.

Darrell_R · Post by **Darrell_R** » Fri Dec 23, 2011 7:57 pm

Judith Arifandi wrote:do you know how to adjust iris shutter? was iris shutter has some kind of screw that could be turned or some thing like that?

Hi Judith,

I also agree with all that John and Rob have said and have attached a few photos that shows an Iris fully open and then closed. Also a couple of pictures of a centering device as well.

Even though I have an Iris for my glasses, I do not tend to use it anymore as my normal prescription with a +0.5 diopter lens fitted that also corrects my astigmatism, gives me a reasonably good / sharp view of my front site, with the rear site slightly blurry and the 10m air pistol target is also slightly blurry. Which is just what I want and a lot of target pistol shooters seem to agree works well for them.

If you do start to use an Iris, just remember what has been said before about the Iris, if you close it down to a small hole to try and achieve a nice sharp site picture, it may also give you a better view of the rear site and sometimes the target as well... Which means you may start to move your focus between the sites and target whilst releasing your shot, which is not good as you really only want to focus on the front site.

Also, if you look closely at some of the photo's, you will see that my lens has a little red line that is lined up perfectly with the joint in the lens holder. This is to make sure that when I change lenses, I can align it perfectly every time.

Hope these pictures help!

Frames with Iris fitted behind the lens and Iris is fully open with the lever shown at the top.

Frames with Iris fitted behind the lens and Iris is closed down by moving the lever on the side of the Iris.

When you have your frames on with the centering device fitted, you should assume your normal shooting stance / position and then line up your lens by moving the lens holder on the frame until you see a nice round hole in the center of your vision. But remember not to tighten the screws holding the lens to the frame too tightly until you have adjusted the lens angles correctly and you can see a nice round hole in the middle of your vision.

Frames with centering device fitted to front of lens holder.

Bye,
Darrell

Judith Arifandi · Post by **Judith Arifandi** » Fri Dec 23, 2011 10:32 pm

wow, thanks guys. I never expect such detail explanation

Darrel : were you using 23mm lensholder? were small lensholder and larger one different?

I personally will try it first, I'll find out the iris will work or not. so no one know shop that I can contact online?

Spencer · Post by **Spencer** » Sat Dec 24, 2011 1:10 am

Judith Arifandi wrote:wow, thanks guys. I never expect such detail explanation

Darrel : were you using 23mm lensholder? were small lensholder and larger one different?

I personally will try it first, I'll find out the iris will work or not. so no one know shop that I can contact online?

the 23mm lens is for rifle - a 37mm lens gets in the way of the stock - and getting the correct sript in the smaller size can be more expensive as most optomotrists do not have machinery to rinfd down to this size.
the 37mm lens offers a lot more eye protection for pistol shooters

I must ask; what makes you think you need an adjustable iris?

Judith Arifandi · Post by **Judith Arifandi** » Sat Dec 24, 2011 1:40 am

in some range, my vision quite blurry. I never found iris shutter in my country. I simply want to learn more about it.

if pistol shooter use small lensholder, it has no disadvantage except the price, right? was the larger one recommended for pistol because it gave more eye protection? 10m didn't use gun powder, do 10m still need protection?

Spencer · Post by **Spencer** » Sat Dec 24, 2011 5:54 am

Judith Arifandi wrote:does 10m still need protection?

Yep! Eventually you will experience a pellet coming back to the firing line.

Darrell_R · Post by **Darrell_R** » Sat Dec 24, 2011 6:48 am

Judith Arifandi wrote: Darrel : were you using 23mm lensholder? were small lensholder and larger one different?

I personally will try it first, I'll find out the iris will work or not. so no one know shop that I can contact online?

Hi Judith,

I use a 32mm lens holder, which is just a personal choice and is in between the 25mm and 42mm options available for my frames. My current frames are Olympic Champion, which is a change for me from the Knoblochs that I used for many years, but recently lost!

Some manufacturers use different size lens holders and accessories, so make sure that if you buy an accessory that is not from the same manufacturer as the frame you use, that you first check that it will fit your frame!

As a general rule of thumb, for pistol you would use a larger 37mm or 42mm diameter lens holder and for rifle, a 23mm or 25mm diameter (Like Spencer said, some rifle users find it much easier to set up their frames with smaller lens due to the positions / stances that they use, which are very different to how you set up for ISSF air pistol).

Sorry, but I do not know an online supplier of Knobloch specific parts that can sell to you.

Also, don't forget to get anti-reflection treatmeant for the lens.. Really does work!

Hope it helps and remember to enjoy your sport!

Bye,
Darrell

Freepistol · Post by **Freepistol** » Sat Dec 24, 2011 10:46 am

Judith,
You have received great information here. With your young eyes you should be able to focus on the front sight with no trouble, unless you are far sighted. Have you had an eye exam recently? If not, you should start there.

If your eyes are okay, it may be a concentration problem. You must force your eyes to see the front sight and not look at the bull. You may actually have your focus between the bull and the front sight and not realize it. The next time you are shooting and have a problem seeing the front sight, point the pistol away from the target at something light in color and see if the front sight comes into focus. You can use the white of the target above the bull if most of the range is dark. This way the black won't distract you.
Shoot well!
Ben

JamesH · Post by **JamesH** » Sun Dec 25, 2011 1:21 am

Are you short sighted?

'Standard' glasses and lenses will be set to move your focus to ~25m, making focusing on a sight pretty hard.

David Levene · Post by **David Levene** » Sun Dec 25, 2011 2:59 am

The OP was regarding astigmatism.

Does an iris help with astigmatism?

Darrell_R · Post by **Darrell_R** » Sun Dec 25, 2011 10:23 am

David Levene wrote:The OP was regarding astigmatism.

Does an iris help with astigmatism?

I have astigmatism and the use of an Iris by itself does not improve my sight picture. Also, the use of an Iris by itself won't turn my egg shaped target into a round one and it won't change my blurry front sight into a nice sharp square one without my prescription lens, which is more important.

However, the use of and adjustment of an Iris will change the amount of light that enters my eye and in turn, changes how and where my eye tends to focus. This is one reason why an Iris can be difficult to use correctly, especially if lighting conditions are not stable or fluctuate between ranges / time of day etc, rather than having a good prescription lens that allows the eye to work normally whilst helping to focus on the front sight. Don't forget, the width of front and rear sights and even the adjustment of the rear sight width under differing light conditions can also affect the front sight picture... Another topic for discussion in itself...

Now this next bit goes even further away from the specific astigmatism question and maybe it should also be another topic, but I feel it remains appropriate for this topic as the original and subsequent posts also suggest that improvement relating to general vision and ease of focus at set distance would be desirable for both performance and comfort.

Personally, for my every day glasses I use my 'normal prescription' that corrects both my astigmatism and also my distance vision, so that I see the world nice and sharp, not blurred.

Then, for my shooting specific frames, I use my 'normal prescription' which is then further changed by having the 'normal prescription' lens made up with a +0.50 dioptre change. I did this as I often found that when my ability to focus was not that great, my focus would start to move down range during the shot release... Not good for me, not good for the result and certainly another topic for discussion,... but...

This +0.50 dioptre difference between my normal glasses and my shooting glasses simply means that the distance that I can normally focus is changed to having very clear, sharp focus of my front sight and my rear sight is slightly blurry and the target is also slightly blurry.

Again, the use of any dioptre variance to normal is a very personal choice that can only be answered by yourself through measured experience whilst working closely with your optometrist who will help identify the exact dioptre variance you require for a clear, sharp front sight picture.

Some dioptre variances to normal utilised by pistol shooters are +0.25, +0.50, +0.75, but this is not definitive and varies greatly between individual’s needs. In basic terms, a +0.25 dioptre is weaker and helps you focus further away than a +0.75 dioptre variance that is stronger and may help you focus closer.

Of course, there are a lot of brilliant sports people that compete at all levels of the sport with no attempt at correcting or improving their vision by the use of a corrective lens to assist focus at a specific distance such as the front sight, so again, it becomes a personal choice, but good vision certainly doesn’t hinder the cause.

Cheers,
Darrell

Judith Arifandi · Post by **Judith Arifandi** » Sun Dec 25, 2011 11:45 pm

I went to my optician, the egg shaped solved
thanks guys for the information, it's really a big help

btw I was told using lenses that is not your needed prescription is against the rules.

Judith

Gerard · Post by **Gerard** » Mon Dec 26, 2011 1:03 am

A bit late in this discussion, and perhaps not relevant... but I bought a pair of Varga shooting glasses from a friend who hadn't used them, had received them as part of the purchase of his Morini pistol. I used the lens which came with the iris for a couple of weeks but it wasn't quite a match for my eyesight (need moderately magnifying reading glasses to focus on the front sight), or so it seemed. Then one day I took the lens mount off the frame to see how easy it might be to cut a new lens into it, from a pair of cheap reading glasses. I noticed as I turned the lens to various angles that objects on the other side were being distorted into an egg shape, which quite startled me. Turns out the lens had a serious distortion built into it. Not all optics are created equal - an understatement to be sure, and the reading glass lens I did mount into the 37mm frame isn't exactly ideal, but it works for now. I've found an optician who is familiar with fitting pistol shooting lenses, just a matter of getting around to spending a day in that suburb while I get a vision check-up and the lens is being made.

David Levene · Post by **David Levene** » Mon Dec 26, 2011 3:50 am

Judith Arifandi wrote:btw I was told using lenses that is not your needed prescription is against the rules.

As far as ISSF shooting is concerned, whoever told you that is wrong.

Darrell_R · Post by **Darrell_R** » Mon Dec 26, 2011 5:28 am

David Levene wrote:
Judith Arifandi wrote:btw I was told using lenses that is not your needed prescription is against the rules.
As far as ISSF shooting is concerned, whoever told you that is wrong.

I agree with David, if you are talking specifically about ISSF Rules for Pistol events and in particular, 10m Air Pistol, my interpretation indicates that, “Correction glasses and/or filters may be worn by the competitor so long as the correcting lenses and/or filters are not attached to the pistol”.

Basically, if it is ISSF air pistol you are talking about, you can have prescription lens made for your shooting glasses / frames that allow you to focus correctly / normally at the front sight of your air pistol. To be safe, make sure the glasses are worn on your head with the lens in front of your eye, like normal glasses and are not attached to the air pistol.

Keep in mind, this is my interpretation of the third printing of the 2009 ISSF rules and there should be no harm in you asking your shooting organisation, association or even your local club about which rules you, as a competitor are controlled by and what their specific interpretation of the rule concerning glasses / frames used for air pistol.

Bye,
Darrell

Darrell_R · Post by **Darrell_R** » Mon Dec 26, 2011 6:08 am

Gerard wrote:I noticed as I turned the lens to various angles that objects on the other side were being distorted into an egg shape, which quite startled me. Turns out the lens had a serious distortion built into it. Not all optics are created equal - an understatement to be sure, and the reading glass lens I did mount into the 37mm frame isn't exactly ideal, but it works for now. I've found an optician who is familiar with fitting pistol shooting lenses, just a matter of getting around to spending a day in that suburb while I get a vision check-up and the lens is being made.

Hi Gerard,

Yep, not all lens are made equal! Especially if you have astigmatism, mounting your lens even slightly off will make a huge difference... In the wrong direction!

Good decision to see an optometrist as well, especially one that has a bit of experience with pistol shooting.

I had briefly touched on this in an earlier post, as had some others, but you really do need to have the lens aligned perfectly to your frames otherwise the astigmatism correction made for your lens will not work..

Here is a photo of what my optician does to my lens to make sure that I align them perfectly every time. (Not that you would normally be taking the lens in and out, but there are reasons why you would, for example if you use prescription filters and only have one lens holder or simply just want to see that it hasn’t come loose and rotated)...

I have my optometrist firstly line up the lens perfectly in my shooting glasses whilst I am in my shooting stance / position and then have him mark the lens exactly next to the lens holder joint. This way I can line up the lens perfectly every time I remove and replace it, or even just to see that it is aligned correctly for my astigmatism.

Cheers,
Darrell

David Levene · Post by **David Levene** » Mon Dec 26, 2011 8:27 am

Darrell_R wrote:
David Levene wrote:
Judith Arifandi wrote:btw I was told using lenses that is not your needed prescription is against the rules.
As far as ISSF shooting is concerned, whoever told you that is wrong.
I agree with David, if you are talking specifically about ISSF Rules for Pistol events and in particular, 10m Air Pistol, my interpretation indicates that, “Correction glasses and/or filters may be worn by the competitor so long as the correcting lenses and/or filters are not attached to the pistol”.

I'm not sure why you say "...and in particular, 10m Air Pistol...". For ANY ISSF pistol event you are allowed to wear a lens but it must not be attached to the pistol.