1.5x front lense

[1000 yards]

I am looking at trying a Gehmann 578-18 1.5 lense for my aging eyes and was wondering if i need to add anything to the rear sight to make it work. Any reveiws on this would be welcomed.
Jeff

[ShootingSight]

It will make the target slightly blurry, but it will magnify it by about 1.5x. This makes the number boards easier to read.

There are two schools of thought on lenses.

When you get old eyes, you are having trouble focusing up close, so a +0.50 diopter lens in the rear will help your eyes shift focus to better see the front sight, and restore your youthful sight picture.

Or, you can put the +0.50 lens up front, where it is too close the the front sight (or even beyond the front sight), so it no longer helps you focus, but instead it makes the target 1.5x bigger.

As someone who studied optics, putting it in the rear (or in your eyeglasses) is a cleaner technical solution, however many top shooters prefer it up front, so I can't say that is a bad solution.

[redschietti]

What about doing both?

[1000 yards]

The target is already so blurry i can not find a clean edge to aim at. The blurr is so large that it makes any kind of accuracy imposible. I have Junker frames with persciption lenses that are 5 years old and i am in the process of working with my Optom. to get new lenses. He will come to the range and use his special frames to insert different lenses to find the best cure. But will this work with a front magnified lense? I haven't seen a rear sight magnifier.I will be shooting 2-3 ISSF sanctioned match's the rest of the time it will be club fun practise shoots. I know the ISSF rule so i would take the mag. lense off and return it on the rest of the shoots i just don't know if this broad range of eye glass's and interchanging the front lense will work?? Or will i have spent alot off money and will still be blind as a bat!!
Jeff

[corning]

I have Junker frames with persciption lenses that are 5 years old and i am in the process of working with my Optom. to get new lenses. He will come to the range and use his special frames to insert different lenses to find the best cure. But will this work with a front magnified lense?

It's good that your optometrist is willing to come to the range to work with you. I have a friend that is an ophthalmologist (also a shooter) who is also willing to share his expertise with shooters. People like that are a rarity.

To answer the question: Shooting glasses will work with a front lens. I currently use a .3 lens on my front sight, and wear Knoblochs with a +2.25 plus an old astigmatism correction. The .3 front lens helps me acquire the target, and number boards. I have vacillated between no front lens, and the .3, and have considered a .5 lens. For now, I am settled with the .3 on the front, and the 2.25 in my glasses.

I also use the glasses for smallbore prone, but the jury is still out on the front lens

A "by the way", without glasses, I cannot see the targets at 1000 yards, they are a big "fuzzball".

John

[1000 yards]

Thank you for the replies. I should of said earlier that this set up is for smallbore shot at 20m and 50m. The 1000 yard is what me and the mrs do with our 50BMG to get ride of this " smallbore stress" lol.I have heard that the lense will cause our front iris adjustment of 2.5-4 to be to small, it may have to now be as much as a 6-7 to fit the magnified target into the iris ring?
Jeff

[DLS]

The target is already so blurry i can not find a clean edge to aim at. The blurr is so large that it makes any kind of accuracy imposible.

The target does not have to be clear at all ... in fact if all you can do is see a smudge you can accurately aim with aperture sights. You can come close with a post as well.

My youngest daughter has nystagmus ... a birth defect caused condition that causes here eyes to shake rapidly back and forth. When shooting a post she centers the blur of the front post on the bottom of the blur of the target and does reasonably well for your age, stature and training. Consistency is the key, not what the actual sight picture looks like.

When she looks through aperture sights this shaking lessens quite a bit, but is still there. She can shoot what are approaching good scores with these sights. Again, she centers the smudge of the target in the center of the circle of light that she perceives coming from the center of the smudge of the aperture. Even perceiving a blurry oblong sight picture (back and forth shake) she can still consistently align the sights and place them on the aiming mark.

No lens system (the human eye included) can focus precisely on more than one point at a time. Even with very young eyes and excellent depth of field, if you are looking at the front sight you will perceive the target as blurred. If you see a sharp edge to the target while aiming you are using the sights incorrectly.

But again, you don't need to see the target clearly at all. If you can perceive it at all, you can center whatever you perceive in the front aperture and you can be very accurate. But you must be razor focused on the front sight ... the interior edge of the aperture to be exact.

I hope this helps.

[1000 yards]

DLS. I had good results when the perscription was new and i had a little bit blured target with a sharp front sight. Now the target is so far gone there is no "aim point" to be accurate [ i'm looking for 575-580 scores]. It is nice that your daughter is shooting so well with her condistion i have not been able to shoot much better that 550's for way to long and i was at the 580's when the eye's were working, trying to get back there.
Jeff

[corning]

I think once you get your prescription updated, you will find less of a need for the 1.5x front sight lens and as such a big aperture (6 to 7) that you referred to. For 20M and 50M smallbore, you might not need any front lens once you get the glasses in order. If you do it may only be a .3 or, on the outside, the .5 you are referring too.

Good luck.

John

[1000 yards]

Thank you for your replies. I have been invited up to try out a 1.3 and a 1.5 at 20m indoor range so i will be able to check them out with the old lenses and compare to what advantage might come from using one. Hopefully by the time the outdoor season comes around i will be ready.
Jeff

[Tim S]

Regarding foresights, if you are using a magnifying lens in front of the foresight, then yes you will need to use a larger foresight aperture. The lens will only magnify the target, so it fills up more of the foresight. You need a larger aperture to maintain the same gap around the target.

I was given a rule of thumb to increase the foresight by about 0.6mm for a .3X lens, and 1.0mm for a .5X lens. So unless you currently use a pretty small foresight, the 4.0mm maximum may not open up enough.

[mobarron]

The front aperture size for a .5x lens will depend on your sight radius and your preference for the ring around the bullseye. At 36" sight radius the usual range of adjustment is between 5mm and 6mm. A +.5 diopter added to your distance vision correction for your shooting glasses usually works for sight radii of around 36".

[1000 yards]

Thanks guys. Right now i have a 36.5 inch sight radius. The front iris is set at 3.4 and the rear is at 1.3. My gunsmith machined a full length rail on the top of my bloop tube so my front sight can go from34" to 42" .My front sight is a Gehmann m-18 with a 2.5-4.5 adjustable iris. I will be doing the indoor test with my gunsmith so if what i have doesn't work he shoots big bore and has some larger front sights that we can play with. And he is more than happy to machine up some magical set up that will work. For now i have my 20x scope on and have been using it at 10m with our scatt set to 50m prone target. It sure looks good as far as form and heart rate goes...just got to get these damn eyes to play nice with the iron's.
Jeff

[1000 yards]

Tried out the .3 lense at 25 meters indoors and learned alot. The sight i borrowed had a max. # 6 iris adjustment and this was put at 38" and it did work but the ring size was on the small size.I tried this lense at both 10m and 25m and the sight picture was the same , clear and sharp. I tried with out my glass's and got " the egg" front ring. With the glass's on the ring returned to round again. I was able to see and have fun shooting again. I will get a .3 lense and also a 5.5 x 7.5 iris to go with it.
Jeff