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shooting glasses
Posted: Wed Dec 14, 2005 2:04 am
by jjjjjjjjjjjj
what does +.25 dipoter and -.25 dipoter mean, normal eye glasses focus on infinity i'm assuming these ones focus on the front sight, right?
Posted: Wed Dec 14, 2005 5:08 am
by RobStubbs
It's not that simple. It typically needs to be between 0.25 and 0.5 and I think it's '+' that brings the focal length shorter. If you get the wrong correction then it won't work and if you get the wrong signage then it will make matters a lot worse.
Best advice is to see an optician/optometrist.
Rob.
Eye Care
Posted: Wed Dec 14, 2005 9:09 am
by Fred Mannis
Jay,
Go to
http://www.starreloaders.com/edhall/nwongarts.html to read Dr Norman Wong's articles on what every shooter needs to know about the role of the eyes in pistol shooting. There is also a lot of other very good stuff on Ed Hall's web site.
Fred
Posted: Wed Dec 14, 2005 2:15 pm
by Bill Poole
diopter is the unit of optical correction.
if 0 diopter (no lens) your eye is focused at infinity
+1 diopter is focused at 1m
+2 diopter 0.5m
+3 diopter 0.33m
etc.
young healthy corrected-if-needed eyes focus with relaxed muscles at infinity and tensing the muscles brings the focus in.
older eyes cannot focus so close because the muscles get weak and the lens gets stiffer, that's why they have reading glasses, large print edition books and grandpa's arms are too short.
a little bit of + correction prevents you from focusing at infinity or even 10m away, so you are more relaxed focusing on the front sight. And the older guys (like most of the ones you shoot with) might not even be able to achieve focus without a + diopter lens.
shoot good
Poole