Rifle Scopes March 2.5x25 eyebox

[Macdaddy]

I am looking at the subject March scope but have read for some time how finicky the eye box is on these scopes. Some have stated that the 52 mm version is friendlier than the 42mm version in regard to the eye box.

Having said that however, I recently spoke to someone who claimed they were advised by the folks who distribute the March Scopes, that the objective diameter has no effect on the eye box.

Can anyone who has looked through both - offer up the real world answer?

Thanks,

 

[SHLowlight]

Well March is rewriting how we determine the exit pupil because that plays into the equation.

Exit pupil matters in the operation of the scope beyond just letting light in, as an example and I grabbed this because I am too lazy to write it all out


You can calculate the size of a scope's exit pupil by dividing the effective objective diameter in millimeters by the magnification. For a 4X 32mm hunting scope, divide the 32mm objective size by 4 and you find that the exit pupil is a generous 8mm in diameter. With a 6.5-20X 50mm target/varmint variable scope, the exit pupil ranges from a large 7.7mm at 6.5X to a smallish 2.5mm at 20X. In a low-light situation, all other factors being equal, a lower magnification setting will provide seemingly brighter viewing than a higher one.

It is tempting to conclude that the largest obtainable exit pupil is the most desirable. But that's not always the case. The catch is that the pupil of a normal human eye opens to a maximum diameter of 5mm to 7mm, depending on the individual, even in extremely dark surroundings. Exit-pupil diameters that exceed about 7mm deliver more light than your eye can accept.

On the other hand, large exit pupils offer advantages beyond simply flooding your eye with light. With riflescopes, one of the blessings of a large exit pupil is greater freedom to position the eye with respect to the optical axis. When you must mount the rifle quickly for a now-or-never shot, you don't have the luxury of placing your eye behind the ocular with the exquisite precision a target shooter can lavish on finding the sweet spot of a 2mm or smaller exit pupil. You'll be truly grateful for the chance a large exit pupil gives you to see what you need to see, even if your eye is less than ideally located.

Exit Pupil on a typical 4.5-14x40mm Scope

@ 8X = 5.0mm
@ 10X = 4.0mm
@ 14X = 2.9mm

Now look at the exit pupil on the 50mm Scope of the same power

@ 8X = 6.3mm
@ 10X = 5.0mm
@ 14X = 3.6mm

So tell March, good try

 

[lennyo3034]

Having said that however, I recently spoke to someone who claimed they were advised by the folks who distribute the March Scopes, that the objective diameter has no effect on the eye box.

"Someone who spoke to a distributor of the product"

I would take that with a huge grain of salt.

I run a March 3-24x42. The exit pupil and eyebox are bad. That's just physics. Depending on your purpose and use, that may or may not be acceptable. It works for my purposes but may not for yours.

 

[Hairy Biker]

Here we go again. The March bashing starts all over.

"Eye box", a marketing term invented by Leupold in the 1990s to explain away the variances experienced in their SFP variable scopes is a function of cheek weld. It is made up of two separate actions: eye relief and exit pupil and much debated. Increasing the front lens diameter has the perceived effect of letting more light into the scope, therefore increasing the flexible of the exit pupil. Bear in mind that a healthy human's maximum pupil dilation is 7mm in low light and anything beyond that in a scope achieves nothing.

So the maths for exit pupil are front lens diameter divided by power range. So a 52mm will let more light through than a 42mm and so have slightly more flexibility in low light conditions.

But consistent and repeatable cheek weld is mostly overlooked in a debate that often seems to descend into vitriol and name calling. On the photo below I have marked the extremes of the eye relief on a March 2.5 - 25 x 52. The key takeaway should be that setting up the scope correctly in the first place is vital to removing sighting errors.

http://i1079.photobucket.com/albums/w507/HairyBiker8/IMG_0571_zpsdx9da5xd.jpg

So, to answer your question. The 52mm lets more light in offering a brighter image over the 42mm in duller light. The "eye box" issue is a beat up from a flawed review that continues to echo around the Internet like a bat in a spin dryer and establishing a repeatable head position/cheek weld when setting up the scope is the most important thing you should do - regardless of brand.

 

[SHLowlight]

Please, Please Please....

You are selling bullshit, Tactical Shooters are across the course type shooters, who do not shoot from a single position hence, the Cheekweld will change when you move in an out of position.

The fact is, Exit Pupil does have a bearing on it, and it's pretty common for people to LIKE or DISLIKE a scope's eye box when moving in and out of position. This is not internet bullshit, it's real world experience from countless sources.

March scopes are F Class and BenchRest scopes that are trying to take advantage of the Tactical Moniker... so in the Prone, with a front rest or on a bench, you can get a good cheek weld and keep it consistent. But once you start shooting off Barricades, from Alternate Position like a Tripod, that all changes. A wider exit pupil is more forgiving vs a smaller one.

 

[Hairy Biker]

The caca del toro is coming from these comments. Flip flopping and personal attacks do nothing for the site. March users in similar action disciplines are not having these issues you continue to bang on and on about.

Go and try Back laying and talk to me about eye box on your S&B.

 

[SHLowlight]

I have not attacked anyone, if you want me to lay on the personal attacks you will know it as they are far from sutble

Flip flopped on nothing ... the 52mm is an improvement over the 42mm end of story. The review you cited was for the 52mm vs my 42, used them both still don't like the 42. It's sitting under the seat of my car as I let someone borrow it and never bothered to fuck with it again.

My S&B scopes are 10x better as they are not trying to crush that much magnification in a tiny package. Funny, I had the option to buy my review March scopes at a DEEP Discount and opted to send them back. Meanwhile I have no problem buying an S&B on my own, and since the beginning own more than 20 of them... not talking about review models either. So putting my money where my mouth is, you see more S&B and NF on my rifles than any other brand.

You have NO DEBATE here, you cannot even respond with something real, instead it's this fake idea we are engaging in personal attacks. Clearly a Joke as I read none.

Most in action discplines are not using March the few that are have cognetive disssoance, they paid too much and are now stuck. Last time I checked March was barely a blip on the radar in these situations compared to all the others.

 

[Steel+Killer]

 

[lennyo3034]

Please, Please Please....

You are selling bullshit, Tactical Shooters are across the course type shooters, who do not shoot from a single position hence, the Cheekweld will change when you move in an out of position.

The fact is, Exit Pupil does have a bearing on it, and it's pretty common for people to LIKE or DISLIKE a scope's eye box when moving in and out of position. This is not internet bullshit, it's real world experience from countless sources.

March scopes are F Class and BenchRest scopes that are trying to take advantage of the Tactical Moniker... so in the Prone, with a front rest or on a bench, you can get a good cheek weld and keep it consistent. But once you start shooting off Barricades, from Alternate Position like a Tripod, that all changes. A wider exit pupil is more forgiving vs a smaller one.

I agree with what you're saying about eye pupil, and really most of your opinions on optics. However I (and at least one other shooter) have been using the X42 successfully on .223 DMRs in competition.

We have been using them in a DMR series with lots of positional shooting and movers. I rarely go above 12x and at low magnification, the March eyebox can hold its own. I treat mine as a 3-12 optic that can be cranked up to 24x when I'm in a stable enough position. The March can not compare to a high end 5-25X56, it would be silly to expect it to. But it does have benefits over comparable sized optics when a larger optic is not appropriate.

I also use a 4.5-27 Razor on another gun that I've shot a few matches with. I find myself using the same lower magnification on it as I do the March for positional stages. Is the March as good as the Razor through the entire mag range? No. Is it as good for the magnifications I use it at? Almost. Is the trade off worth the size and weight benefit on a 10lb AR-15? Yes.

FWIW I replaced a 4-16x42 S&B with the March and haven't regretted it. The S&B had better pop but the ability to crank to 24 on occasion and reduced size outweighs that IMO.

I would not trade my March for anything, except maybe the same scope with 1/6283 adjustments.

ETA: I am in no way saying eyebox isn't a thing. It absolutely is. And the March absolutely has an bad eyebox at high magnification. I'm just saying that at low mag, where I use it the most for positional shooting, the eyebox has not slowed me down.

 

[Clearlight]

To the original poster , ' someone you spoke to ' is incorrect . As mentioned
above , exit pupil is a fraction of mag range and objective size . One scope I
have has a 0.7 mm exit pupil on max mag : about the only time it gets used
that high is for target ID or spotting at ELR distances , not taking a shot myself .

I have no issues shooting on 40x from any position I choose with a 56 front end .
Having the optic / cheek piece etc set up correctly is a large part of the problems
I see whilst training guys to shoot . Just yesterday I got 2 guys shooting better
just by moving the scope back slightly , which had the added benifit of getting
them squarer to the rifle / direction of fire .

There are are a few Metallic Silhouette and Practical shooters using the scope
mentioned in the original post to great effect here in Aus , in fact the
national Silhouette champ runs one : that is in an offhand , no sling position only ,
not bench or prone .

EDIT : as Lennyo said above , most of us are shooting steel on 12 to 15 power .
If you can't get a good sight picture with the 3 -24 on that power , your setup and
position is very wrong and needs work , not the scope .

 

[NotMalware]

Well March is rewriting how we determine the exit pupil because that plays into the equation.

Exit pupil matters in the operation of the scope beyond just letting light in, as an example and I grabbed this because I am too lazy to write it all out


You can calculate the size of a scope's exit pupil by dividing the effective objective diameter in millimeters by the magnification. For a 4X 32mm hunting scope, divide the 32mm objective size by 4 and you find that the exit pupil is a generous 8mm in diameter. With a 6.5-20X 50mm target/varmint variable scope, the exit pupil ranges from a large 7.7mm at 6.5X to a smallish 2.5mm at 20X. In a low-light situation, all other factors being equal, a lower magnification setting will provide seemingly brighter viewing than a higher one.

It is tempting to conclude that the largest obtainable exit pupil is the most desirable. But that's not always the case. The catch is that the pupil of a normal human eye opens to a maximum diameter of 5mm to 7mm, depending on the individual, even in extremely dark surroundings. Exit-pupil diameters that exceed about 7mm deliver more light than your eye can accept.

On the other hand, large exit pupils offer advantages beyond simply flooding your eye with light. With riflescopes, one of the blessings of a large exit pupil is greater freedom to position the eye with respect to the optical axis. When you must mount the rifle quickly for a now-or-never shot, you don't have the luxury of placing your eye behind the ocular with the exquisite precision a target shooter can lavish on finding the sweet spot of a 2mm or smaller exit pupil. You'll be truly grateful for the chance a large exit pupil gives you to see what you need to see, even if your eye is less than ideally located.

Exit Pupil on a typical 4.5-14x40mm Scope

@ 8X = 5.0mm
@ 10X = 4.0mm
@ 14X = 2.9mm

Now look at the exit pupil on the 50mm Scope of the same power

@ 8X = 6.3mm
@ 10X = 5.0mm
@ 14X = 3.6mm

So tell March, good try

What is it that makes the Kahles k624i different from the Nightforce Beast, say, in terms of the sensitivity to eye location since they have the same objective size and similar powers? Is there something else about the optical system that creates that sensitivity?

 

[SHLowlight]

Optical designs matter...

Consider the NF 7-35x which does not suffer the loss of elevation, same thing with the S&B 3-27x.

The length has a bearing, how they put the scope together, several factors go into it.

However it is common knowledge that a scope with a smaller exit pupil is gonna be less forgiving. If you google Exit Pupil / Eye Relief etc, you can find it discussed on several sites, not just here.

These scopes are optical systems, the size, quality, number of lenses, etc, all have a bearing.

 

[Macdaddy]

This has been an exceptionally informative learning experience. I am convinced that the 52mm will outperform the 42mm but I am also being convinced that the March may not be the right fit in the long run based on several comments from several that I respect opinions from.

Size and weight matter to me as this is a hunting rifle application so the NF 7-35 might not do it for me. I want (need) premium optics quality. I have had four Premier Reticles scopes on my rifles but even the light weight version ended up being more than I wanted to carry.

I can easily live with something in the top end of 14 -18 power but I want top tier glass and again, something well less than 30 oz.

Wondering if Lowlight or others could offer a suggestion? I mention Lowlight because it seems he's used about everything out there several times over.

BTW: I have three NF 2.5x10x42s which I love but wouldn't mind a little more top end for my aging eyes.

Thanks again for the engaging and informative feedback about the March scopes.

 

[SHLowlight]

The NF 4-16x is a good option, 30oz on the nose for that... depending on your money situation, the S&B 5-20x is nice, or even the Ultra Short 3-20x.

I like the NF 4-16x, it's on my Proof 260REM and works out great, was actually considering moving it to an RPR I am using.

 

[Hairy Biker]

If weight is an option and you are looking for a hunting rifle scope then NF and S&B and the other "tactical" style offerings are perhaps the wrong options for you.

Top tier glass in light weight need not be FFP as SFP can offer a lighter alternative - perhaps Swarovski 2.3 - 8 at 26 oz is an option to consider. FYI, the SFP 2.5 - 25 x 52mm March that I use on my hunting rifle weighs 24.5 oz and is illuminated.

Ageing eyes are a challenge as the muscles around the lens are less elastic so dilation rates are slower. If you are deep wood hunting, the close ranges and darker conditions mean low range magnification becomes key and I rarely get above 6 power in the trees.

 

[SHLowlight]

Vortex AMG is 28oz and has some outstanding clarity and resolution.

Great cross over scope

 

[lennyo3034]

Vortex AMG is 28oz and has some outstanding clarity and resolution.

Great cross over scope

I'll be honest, for 95% of applications I would take this over the March. If you're not doing specific stuff where you MUST have 3-4x mag, I think the AMG is the better scope. Not sure how it compares to the X52 March as I've never had one.

 

[koshkin]

Interesting discussion. Advance warning: I hate the term eye box and do not use it, so bear with me. To me, this is an eye box:


The size of the exit pupil has an immediate and significant effect on flexibility of eye relief. Small exit pupil means that your eye has to be positioned very precisely behind the scope. However, optical design matters too, especially for how much leeway you have in terms of fore and aft positioning of your eye (less so for lateral positioning).

March scopes are very well built and engineered, but they do have pretty tight restrictions in terms of eye positioning. A lot of it is a consequence of very broad focus range and shallow DOF of the optical systems they use.

A lot of that can be mitigated by proper scope and stock set up, but, obviously not all of it and for disciplines that involve unorthodox shooting positions, March is usually not the optimal choice. Scope selection is a compromise: choose what is important to you. When March first came out with the 2.5-25x42, 3-24x42 and other high erector ratio scopes, you could not get such a broad magnification range anywhere else. Whether you need it is a separate question, but if you wanted ultimate flexibility, March was the only game in town. Now, there is a lot more competition, so it is a different story.

Personally, I liked the original 3-24x42 quite a bit and used it for a few years. However, I mostly shot it in the 8x to 14x range and only dialed it up to top magnification when I had the leasure to do so.

Kahles, mentioned above, probably has the most flexible eye relief of all the precision scope currently available. That and wide FOV is sort of a point of pride for Kahles, so they design their product accordingle. S&B, Minox, Tangent Theta, etc are somewhere in between in and offer a very good compromise of a little bit of everything. Personally, I am a big Tangent Theta fan, partly because of the turrets, partly because of the optics. Eye relief flexibilit on it is very respectable, but not as good as Kahles. Steiner Military scopes also have very flexible eye relief in my experience.

Vortex has really paid a lot of attention to the eyepiece design in recent years (ever since they had to re-design the eyepiece on the Gen 1 Razor) and the eye relief flexibility on the Razor Gen 2 and AMG is excellent. I am currently testing the AMG and I really like it. I prefer lighter scopes, so for my purposes it is a better fit than the Gen 2 (and Vortex is going to get it back from me over my dead body; or if my wife finds out that I am planning to buy it, which may the same thing).

Last point to address: matching of exit pupil to eye pupil. I have heard people say that once the exit pupil of the scope exceed the size of your eye pupil, it is just wasted light. That is simply not true. It gives some space for your eye to move around and increases image fidelity (your brain likes to process multiple images from slightly different eye positions). It also helps with eye fatigue.

Generally, the more your eye pupil dilates the worse is the image quality that they eye delivers to your brain, so in low light, every little bit helps.

ILya

 

[NotMalware]

Interesting discussion. Advance warning: I hate the term eye box and do not use it, so bear with me. To me, this is an eye box:


The size of the exit pupil has an immediate and significant effect on flexibility of eye relief. Small exit pupil means that your eye has to be positioned very precisely behind the scope. However, optical design matters too, especially for how much leeway you have in terms of fore and aft positioning of your eye (less so for lateral positioning).

March scopes are very well built and engineered, but they do have pretty tight restrictions in terms of eye positioning. A lot of it is a consequence of very broad focus range and shallow DOF of the optical systems they use.

A lot of that can be mitigated by proper scope and stock set up, but, obviously not all of it and for disciplines that involve unorthodox shooting positions, March is usually not the optimal choice. Scope selection is a compromise: choose what is important to you. When March first came out with the 2.5-25x42, 3-24x42 and other high erector ratio scopes, you could not get such a broad magnification range anywhere else. Whether you need it is a separate question, but if you wanted ultimate flexibility, March was the only game in town. Now, there is a lot more competition, so it is a different story.

Personally, I liked the original 3-24x42 quite a bit and used it for a few years. However, I mostly shot it in the 8x to 14x range and only dialed it up to top magnification when I had the leasure to do so.

Kahles, mentioned above, probably has the most flexible eye relief of all the precision scope currently available. That and wide FOV is sort of a point of pride for Kahles, so they design their product accordingle. S&B, Minox, Tangent Theta, etc are somewhere in between in and offer a very good compromise of a little bit of everything. Personally, I am a big Tangent Theta fan, partly because of the turrets, partly because of the optics. Eye relief flexibilit on it is very respectable, but not as good as Kahles. Steiner Military scopes also have very flexible eye relief in my experience.

Vortex has really paid a lot of attention to the eyepiece design in recent years (ever since they had to re-design the eyepiece on the Gen 1 Razor) and the eye relief flexibility on the Razor Gen 2 and AMG is excellent. I am currently testing the AMG and I really like it. I prefer lighter scopes, so for my purposes it is a better fit than the Gen 2 (and Vortex is going to get it back from me over my dead body; or if my wife finds out that I am planning to buy it, which may the same thing).

Last point to address: matching of exit pupil to eye pupil. I have heard people say that once the exit pupil of the scope exceed the size of your eye pupil, it is just wasted light. That is simply not true. It gives some space for your eye to move around and increases image fidelity (your brain likes to process multiple images from slightly different eye positions). It also helps with eye fatigue.

Generally, the more your eye pupil dilates the worse is the image quality that they eye delivers to your brain, so in low light, every little bit helps.

ILya

Out of curiosity, where does the Hensoldt 3.5-26x56 fit in your analysis? I've heard that it is very forgiving in terms of eye position. It seem over priced, but that probably because I haven't seen one in person. I'd love to hear that it far exceeds all expectations, and all that...

 

[koshkin]

Out of curiosity, where does the Hensoldt 3.5-26x56 fit in your analysis? I've heard that it is very forgiving in terms of eye position. It seem over priced, but that probably because I haven't seen one in person. I'd love to hear that it far exceeds all expectations, and all that...

Honestly, I never properly tested this scope. The first few I saw were deeply unimpressive (and became even more unimpressive when I saw the pricetag) The one I saw last year was much better. In terms of eye position flexibility, it is decidedly midpack from what I saw and not even close to how user friendly the original 3-12x56 and 4-16x56 were. I sort aforgot about these original Hensoldts and they are on par with or better than Kahles in terms of how much leeway you have with eye position.

If I were hellbent on getting a Hensoldt, it would be the 4-16x56 with the new locking turret. Despite having been around for a while, this is still an excellent design.

ILya

 

[NotMalware]

That's disappointing. I was hoping it was really something...

 

[koshkin]

That's disappointing. I was hoping it was really something...

It may very well be. I never did a proper test. I pre-screen scopes I want to look at and the new Hensoldt was not interesting enough.

ILya

 

[Just Macca]

It may very well be. I never did a proper test. I pre-screen scopes I want to look at and the new Hensoldt was not interesting enough.

ILya

ILya,

I'm sorry to sidetrack this discussion even further, but; how does the Schmidt 5-20 Ultra short fair in terms of its exit pupil and general sensitivity to head position? It will be a crossover target and hunting optic on my DT SRS covert, so compact size and flexible head position is of prime concern.

 

[NotMalware]

I'm interested in the S&B ultra short scopes as well!

 

[KWilson]

I'm interested in the S&B ultra short scopes as well!

I've previously owned a 3-20 Ultra Short. Reasonably comfortable to get behind, more flexible mounting options compared to the 5-20. I hated the MTC function on it. It has a ton of elevation but the clicks are so finely spaced together it just annoyed me no end when I kept dialing beyond what I wanted with the MTC function. Others like it though so horses for courses in that regard.

 

[Clearlight]

I have to second Mr Koshkins assessment of the older design Hensoldt 4-16 .
If ' ease of obtaining full sight picture ' is your top priority , it is a very easy
critter to get on with , if you can live with the reticle choice . I must confess I'm
a little emotionally biased towards the ole Hensoldt as I spent a lot of time on
them back in the day . $7k for the new model seems very optimistic ......

 

[koshkin]

ILya,

I'm sorry to sidetrack this discussion even further, but; how does the Schmidt 5-20 Ultra short fair in terms of its exit pupil and general sensitivity to head position? It will be a crossover target and hunting optic on my DT SRS covert, so compact size and flexible head position is of prime concern.

I have not tested S&B Ultra Short scopes very carefully, but plan to do so later this year. As I recall, the 5-20x50 can get a bit tricky to get behind, while the 3-20x50 was pretty reasonable. Everything has a cost, extreme compactness definitely does.

ILya