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Eyesight/sight picture distortion?
Posted: Mon May 21, 2012 1:00 pm
by WarWagon
Please bare with me as I'm primarily a rifle shooter. When switching to pistol for recreation, I noticed that my sight picture looked like the attachment (please pardon the crude drawing and proportions). If my focus was on the rear sight, the sight alignment looked square. If my focus is on the front sight, the rear sight becomes distinctively trapezoidal in shape, tight at the top, and wide at the bottom.
I was diagnosed many years ago with a slight astigmatism. Is this sight picture indicative of an astigmatism that has gotten worse over the years, or is this something else common?
Posted: Mon May 21, 2012 2:22 pm
by David M
The rear sight is too narrow, widen it out.
When looking at the sight picture the rear sight should appear to be 2-3 times wider than the front sight.
If it is too narrow the sight will flare and appear to be closed in.
Astigmatism
Posted: Mon May 21, 2012 3:03 pm
by luftskytter
I've got astigmatism, but in the other direction.
The top of the rear sight is slightly blurry if I don't use glasses.
But this doesn't limit my score much, other things do......
Shouldn't complain, at 62 I'd be reading newspapers without glasses if it wasn't for astigmatism.
I also notice that the front sight tends to grow "horns" or points at the upper corners. I've heard of people that round the sights off with a file to "soften" this. Edges that come close together and sharp boundaries actually do funny things to light; you'll find it in the physics textbooks.
So it may be more than you eyes playing tricks here.
But you are lucky because the thing you see doesn't seem to disturb the symmetry of your sight picture, so shouldn't affect your accuracy much.
As long as both sides are the same, you're in the middle.....
Posted: Tue May 22, 2012 8:01 am
by ShootingSight
The solution is to get a shooting lens that has your astigmatism correction built in, and also has the correct power for shooting.
If you take your distance prescription, and add +0.5 to +0.75 to the spherical component of the prescription, it will not only correct the astigmatism, but will also move your focus back to the hyperfocal distance of the sights, so your eye will see the sights more clearly, without losing the target.
Art