Rifle Scopes Eye relief and proper sight box

[sharac]

Which scope you think has best sight box and eye relief distance? With that i mean most comfortable and forgiving positioning of an eye behind a scope.

From my experience i'd say:

Swarovski (very forgiving, picture is clean without shades on the edges and allows for very liberal eye placement)
SchmidtBender (i think it requires relatively (compared to Swaro) accurate eye placement however once there picture is clear)
IOR (not longest of eye reliefs but i'd say pretty much up there regarding eye placement maybe a tad more demanding)
Hawke (eye relief ok however there is very narrow box in which picture is good)

I haven't had experience from other manufacturers...

 

[Cartman]

Re: Eye relief and proper sight box

Hensoldt. I think on paper you can look at the exit pupil. I also believe larger objectives lend themselves to larger exit pupils. Get behind a Hensoldt and the sight picture just jumps out at you.

 

[glock24]

Re: Eye relief and proper sight box

I'd like to know what the heck we're talking about when we refer to a better or worse "eye box", or "sight box".

I understand exit pupil, which is simply the diameter of the image column exiting the ocular bell, but what other dimension or feature of this image column affects the "eye box"? And by the way, is the exiting image really in the shape of a column, or is it more of a cone shape, and we simply calculate the diameter of the cone at the designated eye relief? In other words, doesn't this image column collapse to a single point at a spot far enough behind the ocular lens?

Back to "eye box", all I can think of is that is has to do with the depth of the focal plane. It is possible that some scopes have a "thicker" or "deeper" focal plane, meaning you can see the image clearly even with minor fore-aft head movements?

For those of us that need pictures;

 

[jrob300]

Re: Eye relief and proper sight box

What I thought of when I read the OP's post was talked about in another thread; the ability for a scope to "disappear" when you get behind it.

Some scopes take up a large black donut and others appear as a thin black ring in front of my eye.

The other aspect I can think of is what you mentioned, forgiveness of fore/aft without getting blackout or lack of focus.

John

 

[dcjs]

Re: Eye relief and proper sight box

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: glock24</div><div class="ubbcode-body">I'd like to know what the heck we're talking about when we refer to a better or worse "eye box", or "sight box".

I understand exit pupil, which is simply the diameter of the image column exiting the ocular bell, but what other dimension or feature of this image column affects the "eye box"? And by the way, is the exiting image really in the shape of a column, or is it more of a cone shape, and we simply calculate the exit pupil diameter at the proper eye relief?</div></div>

A more precise term would be "eye cylinder" since we are not talking about a cubic area.

You're right about the exit pupil being one factor. If the exit pupil is larger than the eye pupil, the shooter can move his <span style="font-weight: bold">eye side to side</span> and <span style="font-weight: bold">up and down</span> without losing his full FOV.

The other factor is the amount that the eye/head can be moved <span style="font-weight: bold">back and forth</span> without the FOV getting smaller. We all know what happens if you don't have proper eye relief, if you're too close to the scope, the FOV shrinks and the edges get fuzzy, too far away and the FOV shrinks as well, until at a certain distance you are looking at a small circle that is the size of the exit pupil.
The amount of <span style="font-weight: bold">back and forth movement without losing full FOV</span> is a design characteristic of a specific optical system and can be calculated by the optics designer or measured on an individual scope.

So, "eye relief" is actually not a single figure but rather two figures, minimum and maximum. A good optical design will provide enough back and forth movement for the eye of the shooter, and the eye relief range will stay close to constant and in the same position for different magnifications on variable power scopes. This is not always the case, many less sophisticated variables have varying eye relief throughout the magnification range, which makes it necessary to readjust the head position/cheek weld depending on magnification.

 

[bdh308]

Re: Eye relief and proper sight box

Glock24 are you a optometrist by day? Those are some pretty cool diagrams. Makes sense.

 

[sharac]

Re: Eye relief and proper sight box

That is exactly what i meant. To me a forgiving scope is worth a lot more than scope which requires very exact eye placement since to achieve it one might compromise with cheek weld, height of rings, mouting distance etc... What i liked at Swarowski is that somehow once you get behind it it just "falls" in place, finding proper picture is a breeze and keeping it. While with cheaper and even an IOR it's not that easy (not saying bad just different).

 

[dreamlander]

Re: Eye relief and proper sight box

Out of the scopes I own Mark 4, Accupoint, IOR, NF, are all very good with side to side movement and not losing view. These should really be judged at full power were it is usual the worst then even on 22x the NF is better than the others.
Can't say the same for Shepherd or Sightron. Your eye has to be positioned perfectly behind the scope or the image will be greyed out. I hated it. It is alright on the bench but when it comes to hunting and you find yourself in an awkward position and speed counts it is terrible.

 

[Jon A]

Re: Eye relief and proper sight box

Great stuff, David. Could you go just a little deeper into explaining the design attributes that contribute to the fore/aft leeway (length of the "eye cylinder") for a given scope?

"Conventional wisdom" pushed by so many over the years has been this is directly related to the eye relief--that if two scopes are the same power with the same sized objective, the one with longer eye relief will always have a "bigger eyebox."

And yet, while that often is the case, it doesn't seem to always be.

 

[dcjs]

Re: Eye relief and proper sight box

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jon A</div><div class="ubbcode-body">Great stuff, David. Could you go just a little deeper into explaining the design attributes that contribute to the fore/aft leeway (length of the "eye cylinder") for a given scope?</div></div>
To be honest, I don't feel comfortable going any further with explanations here, since I'm not an optics designer myself and as of today, my understanding of optics definitely has it's limitations. I always try to stay well away from unknown ground with statements here because there's hardly anything more embarrassing for me than having volunteered an explanation that lateron turns out to be wrong. Nobody has to know everything, but everyone should know his limitations. There's already far more than enough false concepts about optics in circulation...

If there is a question in optics that doesn't seem to have a universally valid answer, chances are the answer is: "It's a function of the overall design compromise of the particular system."

 

[Jon A]

Re: Eye relief and proper sight box

No worries, I understand. Thanks.