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Best eyebox for a 4-16/3-18 scope?

madangler1

Sergeant of the Hide
Full Member
Minuteman
Feb 25, 2018
137
80
I have a Kahles 3.5-18x50. I like it, but I find the eyebox very sensitive at 12-18 magnification.

What other scopes would you recommend that possess a large eyebox in that magnification range? This is on a bolt gun, so I do not need an ultra short. I picked the Kahles initially because I love my K16i and I like the European style diopter adjustment over Nightforce’s. I am -8.6 to 9D, so going between wearing contacts vs glasses can be an issue for me without adjusting the diopter.

Thanks
 
I have a Kahles 3.5-18x50. I like it, but I find the eyebox very sensitive at 12-18 magnification.

What other scopes would you recommend that possess a large eyebox in that magnification range? This is on a bolt gun, so I do not need an ultra short. I picked the Kahles initially because I love my K16i and I like the European style diopter adjustment over Nightforce’s. I am -8.6 to 9D, so going between wearing contacts vs glasses can be an issue for me without adjusting the diopter.

Thanks
Well here’s the thing, your judging the eye box by the max magnification of that scope. Doesn’t matter what scope, at max mag it’s always finicky. If you want to shoot at 12-18 and not have that, look into a 5-25. Shouldn’t be an issue of eye relief is set properly
 
I have a 3-18 razor gen2 on my 223 trainer. I find that on full 18x the scope is very easy to get behind and find a full picture. It may not be up the the k18 optically, but the eye box is definitely a step up.
 
I’ve never looked through a Tangent Theta but I thought the Premier Heritage 3-15 had the most comfortable eye box I’ve looked through, I’d imagine it’s even better.
 
Thanks for the info. Will try to look through a Hensoldt and Tangent Theta. The Minox ZP is very similar to the Tangent Theta as well, so I will try to look at that.
 
I have a Kahles 3.5-18x50. I like it, but I find the eyebox very sensitive at 12-18 magnification.
I'll assume that since you mentioned magnification, that your eye box issue is with eye relief and not exit pupil?

But if it is the later, the solution is a larger diameter objective as exit pupil is determined by objective diameter divided by magnification, right?
 
I never had an "issue" with the eyebox on my K318i even at high magnifications, in fact, I thought it had a very forgiving eyebox for an ultra short scope. When you mounted it did you set to max magnification and setup so the sight picture was clear when you brought the rifle to your natural hold? Max mag has the most finicky eyebox for scopes and sometimes shooters forget to do this important step when mounting. I do this multiple times (bring rifle up to my natural hold and move the scope forward or back and/or cheek rest up or down to get the ideal sight picture) before I torque down the rings to set the scope and have found the eyebox to be much more forgiving when I do so, I don't care about eye relief or anything like that, it's what aligns with my eye and my setup and my hold that matters.

If you have done all that then I would say take TacticalDillhole's advice and look into something like a 5-25 which is going to be more forgiving in that 12-18 range by design.
 
I second the Right Honourable Lord Hole of Dill’s idea of stepping up the magnification to get more into the sweet-spot in a scope’s eyebox-land. Unless money flows out of your hinder-hole.

And @wjm308, do you wear glasses?
 
Only safety glasses when I shoot at the range, but no prescription
For OP:

I assume you are near-sighted. I’m not sure what I say below applies towards our far-sighted brethren.

I don’t think a greater eyebox is going to solve your diopter readjusting issue, but it will solve some other issues. See below.

For @wjm308:

Ok, good to know. Thanks for answering. What follows is some info that may help people understand the unique issues high-rx eyeglass and contact wearers have (specifically extreme near-sightedness).

I think many high-prescription near-sighted eyeglass wearers have more problems with eyebox than the general population. I know I do. And people with perfect eyes (or even “normal” bad eyes) tend to suggest fixes that help people like themselves. Which is totally normal, of course, but may not help the high-rx eyeglasses wearer.

I have even worse eyes than the OP (-10 to -12), and a generous eyebox is the most important thing I look for in a scope. I usually wear glasses, but I’m starting to test out contacts to see if that makes scope-viewing a little easier. Initial tests seem to confirm my guess.

Diopter issues
As the OP alludes to, scope diopter settings (and rx power) change as one switches between near-sighted glasses and contacts. I don’t believe eyebox differences between scopes are going to change that fact. In other words, you’ll have to change diopter settings between glasses and contacts no matter what the scope.

High RX problem #1
My ophthalmologist confirmed that at my Rx, there is a significant difference between the image size projected on my retina between glasses and contacts. When I switch between them, it takes a few minutes for my brain to readjust. Almost like a mini-vertigo effect.

I’m not sure how “image projection” plays into the problem, but I suspect it does. Essentially, with high-rx near-sighted glasses, it’s as though you are sitting in a dark room away from the TV, and with contacts, you are sitting right up close to the TV, IMAX theater-style. It’s hard to explain, but for an example take some binoculars and look through them the wrong way. That’s sort of the effect I’m talking about. Somehow, optically, this projection effect narrows a scope’s perceived eyebox.

High RX problem #2: optical center/focus point of glasses
I do know people have difficulty looking through the optical center of one’s glasses when behind a scope, and high-rx makes this worse because as one looks through a high-rx lens, there’s a greater relative difference in image quality as you look away from the focus point as compared to low-rx.

This due to how your head is positioned behind a typical rifle and is greatly exacerbated by super low rings, which force the head at an angle away from the perpendicular plane to the scope. Use high rings.

Regardless, there’s going to be some compromise in this area when behind a scope unless you have a special set of shooting glasses made with the focus point more towards the upper left (in a right-eye dominate/right-handed person).

High RX problem #3
Another thing people with high rx near-sightedness tend to have is lots of “floaters”, which are more noticeable the higher the mag you are on the scope (probably because of relative size differences between floater and image). One has to “flick” them away with a quick movement of the eye, back and forth. I’ve had them since youth, and they tend to accumulate through the years (I’m 50).

All that “flicking” tends to also slightly move your head around, and the more eyebox the less re-centering of the head one has to do.

High RX problem #4: down the road – cataracts and retina detachment
Ok, won’t go into this because the effects of cataracts and one’s retina peeling off are pretty obvious, and high rx people tend to have more problems in these areas. In the last month I found out I have a slight cataract in each eye, just like my dad did at my age. Wheeeeee!
 
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Hensoldt 4-16.
if that doesn’t work for you, nothing will.

Uh, yeah, it WOULD work for me, however, I still had to get an ATACR instead.

STILL kicking myself, will likely be rest of my life, for not JUMPING on all those Hensoldt's they were basically giving away a year or two back. Sure they were all mildot but hey, it's a Hensoldt. What I wouldn't give for a 3-27x too.
 
Eh, the 3.5-26x56 Hensoldts were mostly hit, sometimes miss. A good one is absolutely outstanding though.

Having said that, the 3-12x56 example is still my favorite scope, Hensoldt or otherwise, for just about anything .30 cal.
 
For OP:

I assume you are near-sighted. I’m not sure what I say below applies towards our far-sighted brethren.

I don’t think a greater eyebox is going to solve your diopter readjusting issue, but it will solve some other issues. See below.

For @wjm308:

Ok, good to know. Thanks for answering. What follows is some info that may help people understand the unique issues high-rx eyeglass and contact wearers have (specifically extreme near-sightedness).

I think many high-prescription near-sighted eyeglass wearers have more problems with eyebox than the general population. I know I do. And people with perfect eyes (or even “normal” bad eyes) tend to suggest fixes that help people like themselves. Which is totally normal, of course, but may not help the high-rx eyeglasses wearer.

I have even worse eyes than the OP (-10 to -12), and a generous eyebox is the most important thing I look for in a scope. I usually wear glasses, but I’m starting to test out contacts to see if that makes scope-viewing a little easier. Initial tests seem to confirm my guess.

Diopter issues
As the OP alludes to, scope diopter settings (and rx power) change as one switches between near-sighted glasses and contacts. I don’t believe eyebox differences between scopes are going to change that fact. In other words, you’ll have to change diopter settings between glasses and contacts no matter the scope.

High RX problem #1
My ophthalmologist confirmed that at my Rx, there is a significant difference between the image size projected on my retina between glasses and contacts. When I switch between them, it takes a few minutes for my brain to readjust. Almost like a mini-vertigo effect.

I’m not sure how “image projection” plays into the problem, but I suspect it does. Essentially, with high-rx near-sighted glasses, it’s as though you are sitting in a dark room away from the TV, and with contacts, you are sitting right up close to the TV, IMAX theater-style. It’s hard to explain, but for an example take some binoculars and look through them the wrong way. That’s sort of the effect I’m talking about. Somehow, optically, this projection effect narrows a scope’s perceived eyebox.

High RX problem #2: optical center/focus point of glasses
I do know people have difficulty looking through the optical center of one’s glasses when behind a scope, and high-rx makes this worse because as one looks through a high-rx lens, there’s a greater relative difference in image quality as you look away from the focus point as compared to low-rx.

This due to how your head is positioned behind a typical rifle and is greatly exacerbated by super low rings, which force the head at an angle away from the perpendicular plane to the scope. Use high rings.

Regardless, there’s going to be some compromise in this area when behind a scope unless you have a special set of shooting glasses made with the focus point more towards the upper left (in a right-eye dominate/right-handed person).

High RX problem #3
Another thing people with high rx near-sightedness tend to have is lots of “floaters”, which are more noticeable the higher the mag you are on the scope (probably because of relative size differences between floater and image). One has to “flick” them away with a quick movement of the eye, back and forth. I’ve had them since youth, and they tend to accumulate through the years (I’m 50).

All that “flicking” tends to also slightly move your head around, and the more eyebox the less re-centering of the head one has to do.

High RX problem #4: down the road – cataracts and retina detachment
Ok, won’t go into this because the effects of cataracts and one’s retina peeling off are pretty obvious. In the last month I found out I have a slight cataract in each eye, just like my dad did at my age. Wheeeeee!
This is great info, I don't have perfect eyes (used to but age got to me) but they are still good enough I don't need glasses outside of night driving and reading glasses. I think you've posted this before, but I'm making a copy of it for future reference.

STILL kicking myself, will likely be rest of my life, for not JUMPING on all those Hensoldt's they were basically giving away a year or two back. Sure they were all mildot but hey, it's a Hensoldt.
I've been kicking myself as well, I remember EO having them for just over $2k and I think they had more reticles as well, would love to get my hands on one in the classifieds but they rarely come up. I'm now looking at possibly the TT315M as that is another scope I love (had two Premier LT's) as you can no longer find the Premier LT's for sale anymore...
 
Carbonbased pretty much nailed my problems

I am -8.5D with astigmatism wearing contacts (Acuvue Oasys). Glasses, which can be manufactured more precisely, for
me are around -8.75D. I generally shoot with contacts so I can use std safety glasses. It takes my eyes more time to focus though wearing contacts than it used to (just turned 40.....presbyopia is creeping up on me).

I have a Tikka T3x CTR in a GRS stock, and yes, I adjusted the eye relief and diopter the best I could before mounting it. It’s still tough on the 15-18x range compared to say, my SPR’s Nightforce 2.5-10x32 on 10x. My Kahles 1-6x is awesome in that regard; I can look through it all day.

I need to shoot it more (hard to get to the range much with two small kids and working 60+ hrs a week). And yes, I find myself adjusting the diopter when switching between glasses and contacts.

It’s very hard to pick out a scope when virtually no stores in Indy carry this sort of high end stuff. I looked through the Kahles at the NRA convention last year and didn’t have an issue. Maybe I need to adjust my set up some.
 
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Glad my post was accurate for you. Here’s some scopes that work for me:
  • Vortex Razor Gen II 4.5-27 EBR-2c mrad (I found really busy reticles aggravate the whole floater issue…Leupold’s CCH, ahem)
  • Vortex PST Gen II 3-15 and 5-25 EBR-2c/2d reticles
  • Vortex 1-10 Razor Gen III
  • Leupold VX-6hd 4-24 Varmint reticle and 3-18 Impact-29 reticle
Also, I use quite high rings and no/low cheek rests to get my head as square as possible behind the scope. I also make sure I set up the scope so I am physically comfortable behind the scope and relaxed (not stretching).

edit: forgot to suggest NOT using Leupold’s VX-3i’s 6.5-20 lineup. The eye relief is too variable and the eyebox isn’t great.

Good luck!
 
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I went back out to the range today. I have a GRS Bifrost stock, and made some very subtle adjustments to the LOP and cheek piece. It helped a lot along with running the scope at 12-15x magnification. I shot prone which may have helped me too.

More important , I used my glasses rather than contacts. I could see better. I had some trouble focusing between the target and reticle at high magnification (15x) but not as bad as last time. I think I will need to get my eyes checked again soon; my prescription has not changed in years but it may be time.

My Tikka shoots better than me, but I had a magazine crap out on me today. I may also ditch the GRS only because of the grip angle (range of adjustments is great though).
 
Good to hear it was a little better! More tips:
  • Less LOP is easier for me to get comfortable and centered behind the scope. 13.5” or less (edit: I’m 5’10” 185 lbs).

  • With glasses, using a “chin weld” makes it easier to look through scopes vs cheek weld

  • Try a couple of different ways to set the diopter:
    • Normal way: parallax at infinity, looking at a blank, even sky or wall at max magnification, adjust diopter
    • Same as above except dial magnification down before diopter step, as it then is harder to see small numbers (like an eye chart). If you have a 18x max scope, try 10x.

  • Third way to set diopter: I like this cool alternative way diopter setting from @hk dave (first post). He says:
    • “I essentially set up a target and used the parallax knob to get the sharpest image possible. I then adjust the diopter to get the sharpest reticle possible then check for parallax. I did this back and forth until I got a parallax free image with the sharpest image possible and sharp reticle. Then tested parallax at different distances to be certain.
      I’ve found great success with this method…”

So, there you have it! Let us know how it goes.
 
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