New to diopters on rifle, eye strain concerns.

[Davido2005]

Hi all, I’m a relatively experienced air rifle shooter using scopes in field target and hunter, but new to 10m air rifle and diopters (and this forum, hi!).

I’ve recently picked up a Walther Lgr with I believe original sights on with a view to trying some informal club level 10m shooting. I have been sighting in and practising over a few evenings now, and I’m getting some eye strain and fatigue. It’s best described as tired eyes, and sometimes feels like I’ve been looking into the sun or a light bulb. I’m doing lots of research on setting up the sights and technique, but had a few questions.

Can using these sights cause long term sight issues?
Will practise reduce the eye strain as they get used to the task at hand?
Is there one top tip for setting up sights for eye strain? (This seems like a huge topic so I’m trying to get my head round the reading!)

Current setup is a plastic translucent DIY blinder, both eyes open, eye roughly 100mm from iris of sight, rubber shade over iris, shooting indoors in bright lights. I seem to be right handed and right eye dominant. Recent eye test said no need for any correction.

If you have any set up tips that would be great, equally if I just need to get used to it and practise please tell me!

Thanks, David.

[Tim S]

David,

I started shooting smallbore in 1997, almost exclusively with aperture (dioptre) sights. I've noticed no long term strain on m6 eyes. I would make a few comments:

1) Correction - most opticians do not realise what aperture sight shooting entails, so don't assume that no correction is in order. You are focusing in the foresight, and using the extended focal depth of the tiny (ca 1mm) rearsight aperture to make the target visible. Focussing on the foresight can tire your eye muscles, especially if your are long sighted, or getting older. For many adults a +0.5 dioptre lens (or distance correction +0.5) puts your focus just ahead of the foresight, where it's still sharp but the target is a little clearer, without engaging your eye muscles. I'm long sighted and have decent distance vision, but still have a corrective lens for shooting to save consciously focusing on the foresight each time.

2) eye relief - 100mm/4in from your eye to the aperture is fairly long. It's not ridiculous, but on the long side. A long eye relief does make the aperture appear smaller for a longer/deeper focal length, but this comes at the expense of field of view and brightness. Less light reaching your eye can be tiring. Less eye relief gives a wider and brighter sight picture, but loses a little sharpness. However, with a corrective lens this loss of focus doesn't matter as the lens focuses your eye at the right distance.

3) foresight size - this matters. You don't mention this, but it's very important. Many beginners think a foresight that fits the target tightly will improve their aim. Now, it is possible to shoot well this way, even successfully, but it's not ideal IMO. I think a looser fit works better. Firstly your brain sees light better than distance, so looser fitting foresight leaves a bigger and brighter gap around the target. Secondly, it's possible to aim off-centre with a very tight foresight - the inner edge of the foresight is blurred, and you can mistake this blur for a very thin gap. For 10m air rifle, 4.0mm seems a common minimum, and 4.5mm is a good starting point.

[Davido2005]

Thank you very much for your response. I’m a little wary about using lenses when not needing them for day to day life, though this may be illogical.

Unfortunately I can’t get the diopter any further back on the gun. I could explore set back risers etc, though I’m not sure how standard the rails are on the LGR.

The foresight insert is 3.7mm. The inside of the tube is only about 15mm. Again being a non standard (9mm ish) rail it’s hard to buy a new sight. Would a new insert alone be helpful? If I buy a larger insert, would I need an adjustable rear aperture too?

Do you think this is something that may just come about with practise?

[Tim S]

David,

There's no problem with using a lens before you need glasses. I started with a +.5 lens at 26 to correct long sightedness, buy didn't wear glasses (initially for computer work) until I was 34.

Re the rearsight position how far back is it? Normally, only the thumbscrew needs to contact the receiver dovetail, not the whole rearsight dovetail. Also are there any spacers between the buttplate and wood? If there are, and your head is at/near the back of the cheekpiece, take out the spacers. This will bring the sights back to you, and the weight of the rifle too.

Some raisers, like the Centra Club Block and Tec-Hro 2.0, can cantilever backwards. These are available in Walther fitting; I presume that hasn't changed.

Foresight insert - yes I would get another. This 3.7mm might be perfect for you, but you'd still want to try others. A larger aperture insert won't hurt, one large enough that it doesn't touch the target as you aim. However, these 16mm (nominal size based on threads) inserts aren't common. Walther switched to the more common 18mm size nearly 30 years ago. If you can't find any, I'd research whether a new Walther-fit tunnel will fit. This would require re-zeroing the rearsightasany new tunnel is likely to be taller, so check you have some upwards free clicks on the rearsight.

As for a rearsight iris, yes these are useful but I'd find a foresight first. The iris lets you vary the brightness of your sight picture. A simple iris is not too expensive. Colour filters may not help much indoors, although yellow can make the target pop, especially under fluorescent light. Polarisers are pointless unless you shoot outdoors in natural light.

[Davido2005]

Thanks so much. The rear sight could go back maybe 10mm if I mount it like you say with only the thumb screw. There are no spacers on the butt pad. In terms of mainstream adjustable butt pads it looks like they’re no thinner than mine.

I’ve found someone on a forum who makes custom inserts so will order some to fit the front sight. Thinking of trying 4.0,4.2,4.5 based off forum recommendations. I may try an iris at the same time. After that I could look at new sight tunnels and blocks to bring the diopter back.

The sight tunnels seem tricky, I’m not sure what will fit the 9mm rail on the Walther and adapters don’t seem commonly available. It’s something I could explore down the line, unless anyone has any answers for that?

The thread on the iris seems to be about 9.3mm, is this standard? I have no way of measuring the thread pitch.

Should I be trying to focus on the front sight whilst shooting?

[Tim S]

The thread in the rearsight for the iris is nominally 9.5 x 1mm*. Don't worry about this, as it has been standard on most European rearsights for decades, and is the default for iris eyepieces. You actively have to ask to get anything else.

*I think it's not a standard metric thread, but an old British bicycle thread (3/8in x 26tpi) expressed in metric. Why this came to be used for European rearsights I have no clue.

[Davido2005]

Thank you. I’m hoping the inserts may be here soon, and will order an iris to play with.

I had an assistant measure eye relief (did it very roughly myself before!) and it is actually more like 75mm so not as extreme as I thought. Would the rubber eyeshade have an impact on eye relief, as this comes back an extra 30mm or so?

[Tim S]

David,

No, I wouldn't say an eyecup has any effect on eye relief. With aperture sights the rear aperture governs your field of view and focal depth, so it's the distance to this that matters. An eyecup will shade the rearsight, but won't affect the perceived size of the aperture.

Personally I'm not a fan of eyecups as I've managed to knock these askew, blocking my sight picture, too often. Others manage fine though.

[40xguy]

comment removed....

[Tim S]

I think one of the earlier comments referenced measuring the distance from your rear sight to the front sight (sight radius) and getting a prescription for that... BUT... there are some very knowledgeable people who say that's not the way they would do it -- they would add "something" to the prescription.

I think you may have misread my comments. I wrote that a +.5 lens (over distance correction) is common, and focusses the eye ahead of the foresight. Separately I discussed eye relief, the distance to the rearsight, and how this affects focal depth. Nowhere did I recommend a lens focussed on the foresight.

[Davido2005]

Any reason not to use an extension tube to bring the iris closer to my eye? Seems simpler to me and less than a third of the cost of set back rails.

[Dagpistol]

It's how I achieved it David. As you say it is a cheap way of doing it and so far i can't see any reason to spend any more than the cost of a tube. I'm sure others may have different views but for approx £15 or less it's worth seeing if it suits you.
Jim

[alpineboard]

Eye strain topic, 10 m standing indoors, my recent past, have been continuously shooting 21 months now, at first it was 5 eves a week, for approx last 12 months am shooting 7 eves a week.
At first my eyes would get tired , fuzzy at 40 to 50 shots, and I would stop there.
After 6 months, I could shoot 60 to 80 shots and my eyes would be very strong, beginning to end. Not any problem at all at shot 80. Last shot is always 10 center.
Conclusion, for me is, do not give up, if your eyes get fuzzy, hang in there and keep at it. Am using adjustable iris at rear, with 3.8 mm x 1.0 mm front.

[Davido2005]

I’ve been meaning to update this thread, thanks for the reminder!
I’ve changed to a black opaque blinder, larger front sight element, reduced eye relief, bought an adjustable iris (currently at 1.8) and practised! Between all of this things the problem has greatly reduced. I also have found when I shoot outdoors the problem is almost non existent, and luckily my club is outdoors.

I think with some more practise the problem should go away.

Thank you everyone for your advice on the issue.

[Martin H]

Try your rear iris at approx 1.1mm. This will give better depth of field so that both your target and foresight will be closer to being in focus all at the same time.
At 1.8mm you will only be able to see either the foresight, or the target, in focus at one time.
Cheers Martin