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Posted: Wed Oct 19, 2011 10:40 am
by David Levene
Coastwatcher wrote:My prescription shows Sphere, Cyl, Axis, but has blanks for Prism and Base. What do I change to get +.50 diopter?
Sphere. Cyl and Axis are astigmatism adjustments.
Posted: Wed Oct 19, 2011 11:08 am
by Coastwatcher
I knew that Cyl & Axis were, as they are only shown on 1 eye, but I guess I still am not sure about the +.50 diopter thing. Do I add that to the sphere value in my shooting eye? Thanks for the help,
Posted: Wed Oct 19, 2011 2:07 pm
by peterz
That's a really rough guide to correct your prescription from infinity to the roughly 50 cm between front sight and your eye. But you're much better to have an optician check you with your gun in hand than to guess.
Posted: Wed Oct 19, 2011 2:23 pm
by David Levene
Coastwatcher wrote:Do I add that to the sphere value in my shooting eye?
Yes.
If, for example, your prescription is -4.25 then the shooting lens would be -3.75.
If the prescription is 4.25 then the shooting lens would be 4.75.
If the normal prescription for your shooting eye is the one with the Cyl and Axis then you also need them on your shooting lens.
I agree with Peterz however, you'd be much better off having an optician (who understand the requirements for your type of shooting) check it properly.
Posted: Sun Oct 30, 2011 10:27 pm
by mld
As a follow-up, since I started this enquiry, my optician found for me a clip-on +1.0 diopter lens that fits on the inside of my progressive lenses.
The brand name is "Rouglass" and cost me $20 CAD.
My front sight is now perfectly in focus and I can still see the target.
Posted: Mon Oct 31, 2011 1:59 am
by Muffo
I'm thinking of giving that a go ordering a heap of slightly different glasses off them and finding whats closest then going to the optometrist with my findings. I have a good optometrist that has made me about 6 or 7 lenses and hasn't charged me for any of them but so far i haven't been able to get one I'm happy with. I take my gun in we go through a whole series of corrections till i find something that i can see the front sight well, then he gets it made up, I go to the range and just cant see my front sight clear. I have had the one lens for about 2 years now and I could nearly see my front sight with it but now its getting harder and harder to see so Im going to have to have another go at getting one made
Posted: Mon Oct 31, 2011 2:32 am
by David Levene
Muffo wrote:I have a good optometrist that has made me about 6 or 7 lenses and hasn't charged me for any of them but so far i haven't been able to get one I'm happy with. I take my gun in we go through a whole series of corrections till i find something that i can see the front sight well, then he gets it made up, I go to the range and just cant see my front sight clear.
Are you also taking your shooting glasses so that he can see the distance from the eye to the lens. He needs to test your eyes at that same distance.
Posted: Mon Oct 31, 2011 8:00 pm
by Muffo
I sure am. we even tried doing it after his business shut so we could do it in the hallway with a longer distance from the pistol to the wall