1. If you do not have the correct prescription you will of course struggle, go to a good optician, ask if you can take your pistol, and get him to test on hold, and have a lens made that gives sharp clear focus at foresight distance. it will be your long vision plus some, different depending on your arm length and barrel length, and the lens should include any astigmatism if you have one. Plus 0.5 dioptre is incorrect, that is for RIFLE, and gives a focal length of 2 metres which compensates for the peephole of a rear sight.

Beware the cheap options, the exact lens you will need must be correct to tenths of a dioptre, the cheapies are not, so you will be on a compromise.The best Optician we use, and always advise is Stephen Hing at Shefford, near Bedford, and ask to book for Stephen, you will not need to take your pistol as he understands shooting and will test correctly, and he makes his own lens's. Its a hike, but if you want to enjoy your sport go to the best.

2. Get as wide a fore sight as you can, and then open the rear sight width or make a new one if its limited, so you have a big gap at the the rear.

3. Don't waste time with an iris, you want more light not less, all an iris does as well is draw your focus out, and that is the opposite to what you want.

Have Fun
Robin