TargetTalk

Hi, I currently use a -0.29 diopter (ordered as -0.25), I find that while it works reasonably well, I would like to try a slightly lower diopter to move natural focus point back slightly, to improve rear sight focus, blur target slightly more while keeping foresight at optimum.
I would like to try a -.12 or -.15; local opticians can not supply a lens at any thing under -0.25 due to the tolerances their suppliers work to (ordering a -0.12 could generate anything from 0.0 to -0.25 or worse)
So anyone got a source who can supply such a low prescription?
Joe.

Since a good optometrist (or even not so good) has a machine to "read" lenses you might ask him to shuffle through a bunch of .25 diopter lenses to find one with the "slop" you desire.

Actually, I doubt you will see the difference. Do you know what you really have at this point?

BTW, St. Paddy's Day is fast approaching here....always an excuse for blurred vision. Erin go bragh!

Joecon,

If, as you say, you want to move the natural area of focus back (i.e. towards your eye), and you want to make the target a little more blurry, then you need a higher power lens, not a lower power one.

Probably you should find/order a .37 or .50 lens. Generally speaking, opticians do not order or make lens at increments smaller than 1/4 diopter (.25). You might be able to find someone who will work in 1/8 diopters (.12), but I have never heard of any increment smaller than that being made in a consumer lens. That's for two reasons:

1. most people's eyes cannot discriminate in smaller than 1/4 diopter increments. (BTW, I don't believe that anyone can discriminate between a .25 and a .29 lens.)

2. Therefore the manufacturing process for consumer lenses usually is not set up with enough precision to make lenses in smaller increments.

HTH,
FredB

Hi Joe,
When I had trouble seeing the foresight, we tried +0.25 on my normal prescription. When that was too much (couldn't see the target properly) my optometrist volunteered to organise a +0.12 lens (on my normal prescription), which was great.

However you must realise that while they can specially make these lenses they also cost nearly double a standard lens in 0.25 steps.

The usual reason people are very sensitive to small prescription changes is that either they have large pupils or use large rear aperture sizes meaning they don't get the full benefit of increased depth of field from the "pin hole" effect.

(Just remember +0.12 + -0.25 = -0.13 )
Hope this helps
Martin

Hi joe,

You might wish to try http://www.stewardsportsglasses.co.uk/. I should imagine that if anyone can help or advise they can.

Rgds
Rutty

Hi Joe

Rutty is right, JH Steward opticians are really good and i know that they have shipped lenses to shooters in the USA.

E mail them, explain your problem/requirement. If you haven't already had your eyes tested or your current prescription is over 6 months old, get them re tested [Don't mention shooting to your optometrist] and send the prescription by e mail to JH Steward telling him what shooting discipline you require it for. You also need to tell Stewards what shooting frame you use and the lens holder diameter in mm.

Peeps

peepsight wrote:Rutty is right, JH Steward opticians are really good and i know that they have shipped lenses to shooters in the USA.

....so he shouldn't have a problem with Ireland ;-)

peepsight wrote:E mail them, explain your problem/requirement. If you haven't already had your eyes tested or your current prescription is over 6 months old, get them re tested [Don't mention shooting to your optometrist] and send the prescription by e mail to JH Steward telling him what shooting discipline you require it for. You also need to tell Stewards what shooting frame you use and the lens holder diameter in mm.

I'm not certain that this is good advice for anyone, let alone someone who is trying to change their lens by such a small amount. The correction required cannot be calculated. It varies from person to person, your age, your level if fitness, your general health, the lighting conditions on the range, the gap you have either side of the front sight, etc. It doesn't matter how experience an optometrist is, crystal ball reading is not part of their training.

If you just want someone to supply a set lens to close tolerance, try Clive Kay in Warwick Way, Victoria, London SW1 (tel: +44 20 7834 7296). Apart from being a damned good optician he's also been a pistol shooter of some note in his time. (I hope he hasn't retired yet)

Hi Joe

It looks like this thread is starting to fill up with conflicting advice and as they say too many cooks spoil the broth. This I'm sure is not helping your problem and is confusing for you. So i suggest you ignore my post and seek advice from a professional.

Peeps

Hi All, thanks for the replies. To answer/ make comment on inputs;
The lens I have at present was measured recently as -0.29, that's minus .29. My normal distance prescription is minus 0.75 to minus 1 (it has varied between these over last number of eye exams, but -0.75 most recently), the use of the -0.29 lens for me is equivalent to somewhere between a plus 0.46 to plus 0.71 for some one with 'normal' vision. The choice of -0.25 (-0.29) was as result of eye exam during which I used a simulated gun & sights.

I would agree that it is not really feasible to calculate the best value remotely as it is a fine balance to achieve reasonable rear sight clarity with best fore sight focus, & this surely has to vary dependant on the individuals age, general health, condition of the eye, & as mentioned above the geometry of sights in use.
Using zero correction (my natural uncorrected +0.75 eye), & a -0.29 correction (overall a +0.46), I would say that the optimal is somewhere in between, maybe closer to the -0.29 than zero correction.
So I will make contact with the suppliers you have advised to see what they can advise & supply.
Manny thanks for all the contributions.

Slán, Joe.

And by the way - Lá Fhéile Phádraig Sona Daoibh (Happy St Patrick’s Day to all)