I don’t believe this specific question has been discussed, but if it has, I don’t recall it.

I’ve been shooting the same course of fire with different rifles and scopes the past few weeks and today I was struck by how tight the eye box of one scope was as compared with the other two I’ve been using most. My experiences are what reviews of the sights had led me to expect, but is there any way to determine or predict how the eye boxes will differ by looking at factory specifications or other objective data? Or is it really just a matter of looking through and comparing the scopes in person or relying on knowledgeable reviews?

I suspect I know, but I don’t like to answer my own questions, so I would appreciate what the experienced authorities have to say.

It's a matter of looking through the scope, wiggling your head around....

Always happy to share my opinion! Best eye box award goes to Hendsolt. Had a 4-16 some years ago, amazing eye box. Guy who runs one of the local matches I shoot has a couple Hendsolt. Occasionally look through them, watch a few shooters shoot a stage or two. Next a tie between Tangent Theta and Zero Comp.

Interesting question. The one thing I have noticed is as the magnification gets stronger, the shorter the eye box gets. It doesn't seem to have anything to do with the magnification factor, just the actual strength.

Is that what the cool kids are calling "eye relief" these days?

If so, I don't think there is a formula for it like there is for exit pupil diameter if that's what you're hoping for.

The believe the measurement you are looking for is “exit pupil”.

https://www.celestron.com/blog...ief-for-sport-optics

quote:

Originally posted by apprentice:
Is that what the cool kids are calling "eye relief" these days?

If so, I don't think there is a formula for it like there is for exit pupil diameter if that's what you're hoping for.

Eye box and eye relief two different things.

Scopes with a good or forgiving eye box allow your cheek weld to move around a little (side to side/up and down/forward and back) and still get a crisp reticle/target image. Scopes with a tight or poor eye box almost have to have "head in vise" to be in that sweet spot. Tight eye box not as big of a deal if you're a F-Class or BenchRest shooter always shooting from the exact same position and have shot from that position thousands of times. Tight eye box shooting positional, PRS/NRL stuff/hunting.... not ideal. Much more difficult to maintain POA/POI. That POA/POI is what it's all about! Also can shoot faster with a better eye box in those not so pefect positions, not squirming around to find that sweet spot.

quote:

Originally posted by apprentice:
Is that what the cool kids are calling "eye relief" these days?

It's just a fancy name for the margin of allowable inconsistency in cheek placement on the stock.

Eye relief is just one dimension of it. And it's not a box, so whoever came up with that term just confused the matter. It's more like a cone than a box.

The eye relief is the length of the cone, and if it's a variable magnification scope, the eye relief varies. Of course you don't have to abide by the eye relief, but if you shoot much closer you get hard vignetting. If you shoot much farther back, you loose field of view.

The width of the cone isn't calculable as far as I know. The scope's exit pupil is, which also varies by magnification. So, again, theoretically, the wider the exit pupil in relation to the shooter's pupil, which also varies by the amount of light, then the wider the cone. The human pupil range of dilation is like 2-7mm. So if you look at the range of eye reliefs, the ranges of exit pupils, and the compare them to the range of human pupil dilation, then you can get a rough idea of the size of the eye box at various magnifications.

Or you can just pick the scope you think you like and learn to use the thing. I don't see where concerning oneself about the dimensions of an "eye box" is a real thing. It might be for shooters that don't have consistent cheek placement. But I'm looking at it from the perspective of a hunter, not someone who's timing me.

quote:

Originally posted by offgrid:
It's a matter of looking through the scope, wiggling your head around....

I agree.

****
It can be surprising how different eye boxes are. Definitely across brands, and even within a particular brand. For zoom scopes, the higher magnifications result in tighter eye boxes, which can somewhat be guessed by the exit pupil numbers. Scopes can be more or less forgiving with the fore/aft head position, too. IMO a forgiving scope will tunnel a bit bit when not right in the sweet spot, but an unforgiving scope will almost go black.

Nightforce has two 1-8x scopes -- ATACR and NX8. The ATACR has a listed exit pupil of 11.26mm at 1x, where the NX8 is only 7.9mm. That's a big difference and it's very noticeable. The ATACR's advantage at 8x narrows to 3.19mm vs. 3.0mm. I find that minimal claimed difference odd, as the ATACR still is more forgiving at high magnification.

Bottom line -- one needs to get behind different scopes. Sometimes the differences are....eye opening.

quote:

Originally posted by offgrid:
Eye box and eye relief two different things.

quote:

Originally posted by Micropterus:
It's just a fancy name for the margin of allowable inconsistency in cheek placement on the stock.

Thanks to the two of you for your explanations for those who aren’t familiar with the term. I started seeing “eye box” here and in other discussions of scopesights quite some time ago and it took me a while to figure out what people were referring to. And of course, like so many terms shooters have dreamed up for things related to their activities, “box” isn’t very descriptive or accurate, but that’s the term in the lexicon and we’re stuck with it now. I don’t know what else we’d call it—“vision cone,” perhaps—but no one ever likes the alternative terms I come up for things.

Thanks, too, for the other discussion. It confirms what I believed I understood, but I didn’t want to make ignorant assumptions. As explained, whether the size of the “box” matters, and to what degree, depends on the variables of the shooter and type of shooting, but yesterday’s session was the first time I noticed it so much: high magnification; small, distant target; and shooting from an unstable elevated position over an artificial support all made it more difficult with one scope than with others.

sigfreund, do a couple 15-20 1" dot drills nice comfy prone. Scope with a forgiving eye box and a scope with a not so forgiving eye box. Get up and down between every shot.

Think of “eye box” as the width and height of a complete sight picture from behind the optic. This area is in direct proportion to the exit pupil. In a variable magnification optic, the exit pupil will change as magnification changes. This change is in relative proportion to the field of view.

quote:

Originally posted by offgrid:
Get up and down between every shot.

I can only imagine.

quote:

Originally posted by Nick:
This area is in direct proportion to the exit pupil.

The exit pupil may affect the size of the eye box in a particular scope, but it's obviously not the only thing. Otherwise all scopes with the same size exit pupils would have the same eye boxes, and that is clearly not true.

I guess all this is important if you're racing against time. Having a less than optimal sight picture for the purposes of getting off a fast shot. Otherwise, I just don't understand why anything less than a proper sight picture is desired.

I'm looking through a 2-7x36. At 4 power, I have a 9mm exit pupil, bigger than my eye can accommodate at full dilation. It's moderately bright in my room so my pupil isn't dilated to 7mm. With this scope, I have a few centimeters of forward and backward leeway before field of vision is reduced. But I have very little lateral leeway before the scope tube intrudes into the sight picture. May a couple of millimeters at most. After that, it doesn't take much for the scope tube to start to obscure the critical parts of the reticle.

It seems "eye box" is thought of in terms of the top image. When in reality it's more like the bottom image.

This message has been edited. Last edited by: Micropterus,

Micropterus,

have you shot dot drills?

The whole concept of a "forgiving eye box" as I understand it is mostly subjective. It's not really as much an industry term as it is a sport term. It doesn't appear to be calculable (or at least scope makers don't seem interested in calculating it) or you would find it on scope specifications.

Every rifle scope has a range of eye relief (back and forth), and some usually-minimal range of lateral relief (side to side, up and down) that still allows you to see a full field of view. This seems to be an optimal eye box. Deviate from that range a little in any direction, and the field of view starts to become occluded. A little deviation and the reticle and target are still visible, but the edge or edges start to occlude. Deviate even more, especially laterally, and even the reticle becomes occluded.

On my 1-4x24 (30mm tube), at 1x the exit pupil is so big that I have a whole lot (more than I could use) of eye relief where the whole reticle is visible. I can hold it out at arms length and still see the entire reticle and space around it. I can't see the maximum field of view, but I can see the entire reticle and target. At 4 x its less but still a lot.

At 1x, the lateral range is significantly bigger than it is at 4x.

Eye box we're discussing seems to be the most amount of deviation from a full field of view where the target and reticle are still visible. That box is obviously bigger than the optimal eye box. It seems its a function of exit pupil and magnification. I am not sure how tube diameter fits in, but I suspect all other things being equal, a 30mm tube will have a bigger eye box than a 1" tube. I am not sure how 1st and 2nd focal planes would factor in. That may affect it as well.

The subjective part is how much occlusion can you tolerate. What's acceptable to one shooter may not be acceptable to another. I don't like any occlusion, but then again, I'm not competing or being timed. If I had a large animal charging me, a little occlusion may not be a big deal. If you are shooting drills, it may be needed to beat the time of the previous shooter.

Look at 1" target at 100yds. Shift your head just alittle, does reticle stay center on the target? A "forgiving" eye box will allow more movement with out a POA/POI shift.

Shooting dot drills is an excellent drill to show not only how forgiving the scope is, more importantly how consistent we are with our cheek weld. Try this drill, no time restrictions. Take all the time needed, just get up and down between each shot. It's a great drill. Far better off doing dot drills then shooting groups. Say you and your gun can shoot a 1/2" group at 100yds, cleaning a 20 shot 1" dot drill would be exceptional shooting. Have fun!

quote:

Originally posted by offgrid:
Look at 1" target at 100yds. Shift your head just alittle, does reticle stay center on the target? A "forgiving" eye box will allow more movement with out a POA/POI shift.

Shooting dot drills is an excellent drill to show not only how forgiving the scope is, more importantly how consistent we are with our cheek weld. Try this drill, no time restrictions. Take all the time needed, just get up and down between each shot. It's a great drill. Far better off doing dot drills then shooting groups. Say you and your gun can shoot a 1/2" group at 100yds, cleaning a 20 shot 1" dot drill would be exceptional shooting. Have fun!

Can the dot drill be shot from the bench, or does it need to be prone?

quote:

Originally posted by SgtGold:

quote:

Originally posted by offgrid:
Look at 1" target at 100yds. Shift your head just alittle, does reticle stay center on the target? A "forgiving" eye box will allow more movement with out a POA/POI shift.

Shooting dot drills is an excellent drill to show not only how forgiving the scope is, more importantly how consistent we are with our cheek weld. Try this drill, no time restrictions. Take all the time needed, just get up and down between each shot. It's a great drill. Far better off doing dot drills then shooting groups. Say you and your gun can shoot a 1/2" group at 100yds, cleaning a 20 shot 1" dot drill would be exceptional shooting. Have fun!

Can the dot drill be shot from the bench, or does it need to be prone?

Sure! Pick up your rifle, rear bag.... whatever you use. Walk a few feet away from the bench if you can with all your stuff between each shot.

quote:

Originally posted by offgrid:
Look at 1" target at 100yds. Shift your head just a little, does reticle stay center on the target? A "forgiving" eye box will allow more movement with out a POA/POI shift.

I can certainly see where parallax issues can be problematic in timed events. In hunting, you have time for consistency, and consistency is critical. But in hunting with a scope with parallax set at 100 yards, parallax isn't a huge issue out to about 200 yards. And if you're consistent, it's not much of an issue at all. But at 300 yards on a small target and a less than optimal cheek weld, parallax might be the difference between a shoulder hit and one that is through the bottom of the neck.

I hadn't even thought of parallax issues in the context of this discussion. So, with the types of scope Sigfreund is talking about, do they have parallax adjustments? If not, at what distance are those types of scopes set for parallax at? If it has parallax adjustment and in a timed event you don't have time to use it, how are you compensating for it? And how do 1st focal plane and 2nd focal plane features factor in?

Yes, all the scopes I’m referring to/have experience with have parallax adjustments. The only scope I’ve had in recent times without the feature was a Leupold Mark 6 1-6×. I don’t know what the factory setting was, but probably 100 to 150 yards.

Corrected the model number: Mark 6, not 4.

This message has been edited. Last edited by: sigfreund,