Scopes, prescription glasses and wonky eyes

Rifle scopes, iron sights and optics. Spotting scopes and target acquisition devices.

Scopes, prescription glasses and wonky eyes

Post by Bent Arrow » 13 Dec 2016, 9:12 pm

Hi, I'm a new member, looking for some advice. Recently decided to get back into rifles after more than 20 years away from the sport. Bought a tikka t3 Hunter in 25-06, fitted with a zeiss terra 3X 4-12x50 with the z8 reticle. Main use will be mid range goats in the hills. I've had to take on prescription glasses since I last shot regularly and I'm finding that when shooting prone I am looking over the top of my glasses, rather than through them. I understand that this should be a relatively easy fix via a trip to the optometrist. The other problem is that whilst after just a couple of boxes, i have managed to shoot a couple of sub MOA groups at 100m, my point of impact shifts by up to 3". I have noticed that if i move my head position behind the scope, the reticle shifts on target. I suspect this might be partially related to parallax as the scope with this recticle is set to be parallax free at 300m. Would parallax cause that sort of shift in impact, or is it more likely to just be down to poor shooting form on my behalf ie inconsistent cheek weld, poor trigger control etc. I'm guessing I need to relearn how to shoot and get fussy about form, but don't want to drive myself mad trying to fix something that is inherent to the scope.
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Re: Scopes, prescription glasses and wonky eyes

Post by Wm.Traynor » 14 Dec 2016, 11:56 am

After looking up your scope on the web site I am none the wiser about the parallax adjustment. I would have thought the scope would have a knob or ring for making an adjustment from say, 25M to infinity. The website says it is parallax-free. Sorry mate; I'm on a learning curve but you are right about head position making the reticle move If the parallax is not adjusted.

As for your specs and shooting prone. You can get a frame to hold one lens for your shooting eye. I still have two; a Champion and something else that I forget. Knobloch is another brand. If you visit an NRAA range where F-Class is shot, you might find someone who shoots telescope with glasses. It is rare to find someone like that however, so good luck :)

If your parallax is wrong, then a shooting lens won't help. That needs to be fixed first. I hope someone here can help.
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Re: Scopes, prescription glasses and wonky eyes

Post by Bent Arrow » 14 Dec 2016, 4:11 pm

Hi, thanks for your reply. With the terra 3x scopes and rz reticals, there is no parallax adjustment, and they are set to be parallax free at 300m rather than the standard 100 m for fixed parallax scopes. I guess this directly implies that there must be some parallax error at 100m. I'm more than a little curious to know how much there might be and if that would explain the point of impact of groups shifting by an inch or more at 100m?
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Re: Scopes, prescription glasses and wonky eyes

Post by Apollo » 14 Dec 2016, 4:11 pm

It's supposed to be Parallax Free from 100-300 Yards. At 100 Metres you would need something else to be wrong other than parallax to shift the point of impact 3", a bullet width or perhaps two at worse case. I've got a 4-12x42mm Terra on a .22LR and up to 200 yards I can't detect any parallax shift. Maybe your model and/reticle are different.

I'd say you are doing something wrong.

As far as Prescription Glasses go you can get them built with the focal point shifted from centre to the top left corner and if you are looking over them then you need higher / bigger frames. My target prescription glasses (modified focal point) I get from Specsavers at around $35.00 complete. Cheap frames, plastic lens and all you need to do is get someone to put a dot on a pair of glasses with a texta where you are looking at the exit pupil on the scope and they will have them made to that specification. Cheap as chips.

Problem is for hunting you are going to be changing glasses for proper long sight focus in the middle. Catch 22.

The other point is if you keep your head / eye in the same position every time then the parallax will be negated and your POI will remain constant as opposed to moving your eye around the scope.
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Re: Scopes, prescription glasses and wonky eyes

Post by Bent Arrow » 14 Dec 2016, 4:37 pm

Thanks Apollo. Like most things in life, I suspect the problem with shifting point of impact is entirely operator error, not the equipment but wanted to get a reality check. I've never been sniper material, but used to better than I am now. Here's hoping I can get back on form with some practice.
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Re: Scopes, prescription glasses and wonky eyes

Post by Apollo » 14 Dec 2016, 4:54 pm

Stick with it. Consistancy in everything like grip, shouldering and mainly head position should bring back memories.

I'll be 67yo next year and I still enjoy long range varminting, even though there's not much walking involved these days for me. I love target shooting as well and I'll give up if I can't hit an Orange at 500 metres, a Golf Ball is still very much the target aim size.

My top rifle I have a March Tactical 8-80x56mm and I can tell you that anyone not used to high power scopes has a battle to get an image when they first line it up and typically complain that all they can see is a black reticle... experience is all that is needed, I can sit behind that scope with my eyes closed then open them and a perfect image every time... it's practise keeping your shooting position constant in my view.

Shooting with that power scope I sometime tend to get a little distracted when I see tiny little 2mm black ants or a tiny fly crawling on the target, just can't help putting them out of their mysery and off my target. :thumbsup: at 2-300 metres that is, 500m for an ant is pushing the friendship I have with my rifle.... :lol:
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Re: Scopes, prescription glasses and wonky eyes

Post by Bent Arrow » 14 Dec 2016, 5:08 pm

Yeah I think it's going to come down to practice..... 80x scope, wow!
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Re: Scopes, prescription glasses and wonky eyes

Post by brett1868 » 14 Dec 2016, 5:38 pm

As my old mate Apollo pointed out, you need to get consistent with you eye position behind the scope. You may need to build up the stock with a pad so that everytime you put cheek to stock it's in the exact same position. The GRS Berserk aftermarket stock for the T3 has adjustments for cheek height and length of pull if that's an option for you. There are several after market stocks available or possibly a slip-on pad is all that's need, just depends on how far you want to go. I also have issues with my sight and had a custom set of glasses made for pistol shooting due to the open sights being a blur. Your scope has a +/-2.5 diopter adjustment, have you tried setting this up with and without the glasses on?
How I set Diopter - I cover the objective with a bit of white paper and sticky tape, aim the rifle at a light, set my cheek weld / eye position and check how sharp the reticule appears. Looking at the reticule I adjust the diopter till I have the sharpest image at min & max zoom. Close my eyes or focus on something else at distance then switch back to scope, if still sharp i'm done otherwise I'll make small adjustments till I can get instant sharpness without my eye having to focus on the reticule.

Good vid below that explains what I'm talking about :)
https://www.youtube.com/watch?v=hZK4vq6IFaw
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Re: Scopes, prescription glasses and wonky eyes

Post by Bent Arrow » 14 Dec 2016, 7:18 pm

Thanks, I'll try that paper trick to nail the focus.
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Re: Scopes, prescription glasses and wonky eyes

Post by redrum » 15 Dec 2016, 10:31 am

Apollo wrote:My top rifle I have a March Tactical 8-80x56mm and I can tell you that anyone not used to high power scopes has a battle to get an image when they first line it up and typically complain that all they can see is a black reticle...


Even way less than 80x.

20x - 30x, first time someone sits behind one they're bobbing all over the place trying to figure out what's wrong with the scope :lol:
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Re: Scopes, prescription glasses and wonky eyes

Post by Apollo » 15 Dec 2016, 11:43 am

It's actually funny to watch. Even when they have a look to see if the Lens Covers are still installed.

Another one is watching the head bob up and down then sideways with the next comment being "the parallax is out" ...Er, adjust it....!!!! :unknown: :thumbsup:
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Re: Scopes, prescription glasses and wonky eyes

Post by brett1868 » 15 Dec 2016, 12:09 pm

20x - 30x, first time someone sits behind one they're bobbing all over the place trying to figure out what's wrong with the scope


Try a red dot or a scope on a pistol for some real fun...they move the pistol, then the head and finally both trying to see the dot / reticule :D
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