Prescription lenses for shooting glassea

[derekm]

Rob, you're getting near. The sphere is the main part of your prescription, the magnification if you like. Base your shooting estimation on the "near" or "near/reading addition" of the prescription and make your estimation from that.

My right eye sphere is +0.25 and the near addition is +2.25 (near sphere = +2.5). I ordered lenses to +1.0 and +1.25. with the astig cylinder as prescription. At the moment, the +1.0 is correct.

My last pair of lenses from 2 years back were +0.5 and +0.75. As my eyes degraded I went from the former to the latter.

Whatever your own figures, your shooting lenses will be less strong than your reading lenses and stronger than your distance.

Sorry if I can't put it into better words!

[RobF]

Rob, you're getting near. The sphere is the main part of your prescription, the magnification if you like. Base your shooting estimation on the "near" or "near/reading addition" of the prescription and make your estimation from that.

My right eye sphere is +0.25 and the near addition is +2.25 (near sphere = +2.5). I ordered lenses to +1.0 and +1.25. with the astig cylinder as prescription. At the moment, the +1.0 is correct.

My last pair of lenses from 2 years back were +0.5 and +0.75. As my eyes degraded I went from the former to the latter.

Whatever your own figures, your shooting lenses will be less strong than your reading lenses and stronger than your distance.

Sorry if I can't put it into better words!

No, that makes perfect sense thanks. I never quite twigged the near sphere just altered the distance. That makes sense.

[derekm]

The sphere is the degree of magnification, whether near or distance. Less is required for distance focussing, more for reading and somewhere between for pistol, desktop computer etc..

If you have astigmatism, your eyes produce a "squerged" image, (a square becomes a parallelogram), but for mild cases, the brain corrects this. The cylinder, tilted at an angle, feeds a corrected image to the brain and this correction is the same for both close-up or distance. When you first get astig. corrected glasses, because they over-ride your brain, you tend initially to get a squerged image and may, like me, take the glasses back saying they are wrong! After a couple of days, your brain re-adjusts to the now correct image it is receiving.

Prism, I do not really understand, but I think it is correction for cross-eyes.

[vbull]

So, for shooting purposes what difference does it make where the datum is, whether at 9 or 12 o'clock ?

[Sir_SwampThing]

So, for shooting purposes what difference does it make where the datum is, whether at 9 or 12 o'clock ?

I image that the rotation of the lens affects the amount of correction? If the lens is mounted with the datum point in the wrong position, it would possibly increase the astigmatism instead of correcting it?
Or am I way off?

Cheers
Chris

[derekm]

I image that the rotation of the lens affects the amount of correction? If the lens is mounted with the datum point in the wrong position, it would possibly increase the astigmatism instead of correcting it?
Or am I way off?

Cheers
Chris

Yes and no. Rotating the lens will put the correction in the wrong axis relative to your eye and screw up the image.

[vbull]

Thanks, the penny's dropped.

[derekm]

So, for shooting purposes what difference does it make where the datum is, whether at 9 or 12 o'clock ?

It doesn't per se. Nothing to do with shooting purposes, it is aligning the cylindrical form built into the lens to your eye. The datum, reference point or whatever you want to call it lets you turn the lens to the correct position. If the lens maker puts the mark at 9 o'clock, you put it in the frame at 9. 12 o'clock, install at 12.

If you already have glasses with astig. correction, look through one lens and rotate the glasses. The image will become distorted and the penny will drop.

[RobF]

The sphere is the degree of magnification, whether near or distance. Less is required for distance focussing, more for reading and somewhere between for pistol, desktop computer etc..

If you have astigmatism, your eyes produce a "squerged" image, (a square becomes a parallelogram), but for mild cases, the brain corrects this. The cylinder, tilted at an angle, feeds a corrected image to the brain and this correction is the same for both close-up or distance. When you first get astig. corrected glasses, because they over-ride your brain, you tend initially to get a squerged image and may, like me, take the glasses back saying they are wrong! After a couple of days, your brain re-adjusts to the now correct image it is receiving.

Prism, I do not really understand, but I think it is correction for cross-eyes.

Got it.

I've got astigmatisms in both eyes.

[derekm]

Me too, mild in the left and more pronounced in the right.

Just fitted one of the new lenses yesterday and have a marked improvement in my shooting already.
The sight image with the two year old prescription was good, I thought! How wrong!!

A few years back I had a PB of 94 and averaged 87.5 over 100 rounds. This deteriorated with my eyes until I was hard pushed to score an 80!
Hopefully I'm now on the road to improvement after a couple of 87s last night!

At only £15 a pair, it's worth trying a few strengths of lens.

[BigEars]

Me too, mild in the left and more pronounced in the right.

Just fitted one of the new lenses yesterday and have a marked improvement in my shooting already.
The sight image with the two year old prescription was good, I thought! How wrong!!

A few years back I had a PB of 94 and averaged 87.5 over 100 rounds. This deteriorated with my eyes until I was hard pushed to score an 80!
Hopefully I'm now on the road to improvement after a couple of 87s last night!

At only £15 a pair, it's worth trying a few strengths of lens.

Did you get tinted or plain, Derek?

[derekm]

Sorry for the delay Alan, been in Aberdeen for the weekend.

My lenses are plain, for 10m pistol. I think tints are £10 a pair extra.