Open Sights and Astigmatism


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tpelle
January 23, 2008, 07:39 PM
I'm a 55 year old shooter with very bad astigmatism. I normally wear gas permeable contact lenses that are toric cut to correct for it, and my vision is pretty well corrected to 20 x 20. I'm also VERY myopic, and when I wear glasses I notice that, if I move my head from sided to side, I can make vertical lines "hula" a little - contacts don't do this, however, which is why I prefer them.

My problem is that, no matter which rifle I try to shoot, it seems like my POI is always to the left of POA. For some reason, this does not seem to happen with hand guns. However, every rifle I own - M1 Garand, M98K Mauser, Mosin Nagant, CETME, Yugo SKS, and my own home-built FAL all seem to exhibit this.

My first centerfire rifle was my FAL, and I just thought my barrel was mis-timed, especially since I did it myself. But EVERY rifle I own can't be wrong.

Can an astigmatism do this? I asked my Doctor, but he's not a shooter, and couldn't (or wouldn't say). Is there any other cause for this happening?

Getting kinda frustrated with this.

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P-32
January 23, 2008, 07:59 PM
I have astigmatism as well but maybe not as bad as you. I wear glasses because my body thinks contacts are evil. I have not noticed my shots always going left on when shooting a rifle. If they do, I put windage on and center things up again. I do shoot pistol and find my shots go left if I'm too heavy on the trigger, or don't have a good NPA. Trigger finger could have something to do with it but I would think not so much on a rifle. I won't suggest a flinch but this almost always go left and low.

tpelle
January 23, 2008, 08:18 PM
Hmmm.....a flinch.....could be. Haven't had much trigger time for the last few years, and many of the rifles I do have have pretty rough triggers, so maybe I'm flinching and jerking the trigger.

When it warms up a little I'll go to the range - maybe take the 10/22 with Williams peep sight.

paintballdude902
January 23, 2008, 08:50 PM
im 17 and i have one too but mine isnt that bad, and i dont really where anything for it even though i have glasses i just keep them in my truck becasue i used them on my drivers test

but when i am using some iron sight like on my enfield the post and thing around the front sight kinda blend together

i have noticed the same thing a bit my shots are all to the left also but not bad

i just adjusted my windage for it though


you might try asking around the range my range master told me a few things like he gave me a can of sight blackout becasue my eye will try and focus on the glare if its on ym front sight and i wont shoot as well

wally
January 23, 2008, 11:19 PM
I recently had my astigmatism fixed with Lasik. Can't say for sure because I was never able to really get used to the toric contacts which slipped a lot on me.

But I suspect distortion when you don't look straight on axis thru the correction (what causes the vertical lines to "hula" when you move your gaze) is what causes the bias. The effect is much more pronounced with glasses since they sit out in front of your eye magnifying the error.

The "line" from front to rear on a handgun is probably not long enough for the distortion to cause significant error in sighting. Also you hold the handgun pretty much in front of your eye so you are basically on axis, with a rifle you tilt your head to get a cheek weld which can easily put your eye's axis out of parallel with the sight axis.

Its your gun and your eyes, that's why rifles generally have adjustable sights so you can null out any bias. The direction of the bias would depend on the axis of your astigmatism and the fit of the stock.

My astigmatism was so bad I'd see two reticles in the scope or two front sights so I had to something. I went to Lasik after glasses didn't work (too much distortion in my everyday work) and the contacts I just couldn't get the hang of, but I might have been more motivated if they didn't slip so much when I needed them the most -- after fast eye movements to check mirrors while driving!

Its only been three weeks, but I'm really enjoying rediscovering iron sights!

--wally.

tpelle
January 24, 2008, 09:59 AM
Thanks for all the replys.

I really don't notice the "hula" effect with contact lenses. Luckily I am very tolerant of contact lenses, and have been wearing hard lenses in one guise or another since 1972 or so. I've really thought hard about Lasik - I know some friends who have had it done, one a police officer and one a firefighter - and they both recommend it.

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