Prescription lenses for shooting glassea

[derekm]

Just had lenses made for my Knobloch shooting glasses, only £15 for two different strengths, 2 way postage included from:-

https://www.reglaze-glasses-direct.c...SAAEgLaz_D_BwE

Best to send the lens and lens holder as I just sent a sample lens and the new ones came back slightly small and needed a little packing added for the holder to grip. Otherwise, 100% and better than the £30 odd (?) each I've heard quoted elsewhere.

At first I thought they had screwed up with the prescription, but they had put the datum mark for astig. correction at 9 o'clock when I expected it to be at 12 o'clock!

[RobF]

do they have the focal length set to the fore-sight?

[vbull]

Can you explain this datum mark for the astigmatism bit please ? I've looked at my prescription and can see nothing about astigmatism.

[BigEars]

Can you explain this datum mark for the astigmatism bit please ? I've looked at my prescription and can see nothing about astigmatism.

Maybe you don't have it. When i had mine made the optician asked where i would like the mark to be. I opted for 12.00.

[derekm]

Rob, up to you to decide the sphere value for a good foresight. If you don't have astig. or prism problems, try out some ready readers to get what will usually be a +ve value. If you have a negative prescription you'll have to estimate from the "near" or "reading" value. If you have astig. you'll have to estimate the sphere from the near value on your prescription. A pistol shooting lens will be weaker than reading, stronger than distance.

Until my astig. became noticeable (and before the Knobloch frames came along at a giveaway price!) I used a ready reader frame with a lens made by an internet Co. like reglaze.

[RobF]

Rob, up to you to decide the sphere value for a good foresight. If you don't have astig. or prism problems, try out some ready readers to get what will usually be a +ve value. If you have a negative prescription you'll have to estimate from the "near" or "reading" value. If you have astig. you'll have to estimate the sphere from the near value on your prescription. A pistol shooting lens will be weaker than reading, stronger than distance.

Until my astig. became noticeable (and before the Knobloch frames came along at a giveaway price!) I used a ready reader frame with a lens made by an internet Co. like reglaze.

Hi Derek,

Ah I get it, so the sphere is just the focal length adjustment on top of your prescription? ... so say my right eye is +1.25 to start with, then to focus at the foresight say at 1m, then I just add 1D. If it was at 2m away i'd add 1/2m = 0.5D If I want to focus at 0.5m then it would be 1/0.5m which is 2D.

Does that sound right?

I've got an astigmatism. Trouble is some opticians round the angle up to 5 degrees. Mine is actually 92... some write it as 95. But at least with shooting glasses you can fix it easily by rotating the lens.

[derekm]

Can you explain this datum mark for the astigmatism bit please ? I've looked at my prescription and can see nothing about astigmatism.

If there's nothing on your prescription for "cyl" (cylinder) and "axis", you don't have astigmatism.

If you do have astig. your prescription will have something like cyl -2.75, axis 140 as well as the spherical value. The 140 is degrees from the datum. My last lenses had datum at 12 o'clock, these new ones it's at 9.