Rifle Scopes School me on 1" vs 30mm vs 34mm

[Okie Gordon]

I know very little about scopes and want to educate myself specifically about the various scope body diameters available.

What are the advantages and disadvantages of going with a specific diameter when looking at scopes.

There are lots of 1" scopes available so why wouldn't all scopes be 1" in order to keep things consistent?

Also, if anybody has any good links to articles comparing such things I would like to see them.

 

[roggom]

Look at the internals of a scope and you will get the idea. The larger diameter scope body had more physical room to move the internal erector tube. Larger external tube equals more elevation travel.
Here is a pic of a SS posted by SWFA, found on the net.

One advantage of a 30mm tube is the ability to dial out to approx 700Y with a 308 or 800Y with a 7mm mag, without the need for a canted rail. Only con is most larger optics are a bit heavier.

 

[RFtinkerer]

More adjustment range. And that can make a significant difference. That's all there is I believe.

 

[thegrayham]

That's a great cross section view.

 

[tylerw02]

I know very little about scopes and want to educate myself specifically about the various scope body diameters available.

What are the advantages and disadvantages of going with a specific diameter when looking at scopes.

There are lots of 1" scopes available so why wouldn't all scopes be 1" in order to keep things consistent?

Also, if anybody has any good links to articles comparing such things I would like to see them.

There are two reasons why scopes have a diameter main tube. First, to provide more erector travel. Secondly, so that they can be thicker and stronger.

Most US hunting scopes have been 1" to be lighter and more stream line.

Then people started shooting longer and longer ranges needing more travel.

Finally, the 34mm and 35mm are for big strong tubes with plenty of travel.

There is no standard to keep things consistent any more than there is a standard hammer for all jobs. You select the right tool for the job.

 

[Okie Gordon]

The picture is great.
I am looking for more clinical type of information.
What about the amount of light that a larger tube diameter can allow thru?
Does the larger body allow for more durable internals? I don't see a lot of wasted space inside the cutaway picture so are the guts of a 1" scope smaller and thinner to allow them to fit?

I am a technical type of guy and would like to understand the differences that would get manufacturers to spend more money coming up with bigger diameter bodies.

If nothing else, is there any difference between the internals on 1" and 30mm scopes or is it just a bigger package holding the same internals?

 

[BobinNC]

Okie,

A bunch of articles here DEMIGOD LLC Gun Writing by Zak Smith, many are on rifle optics. Some are dated as far a products go, but this particular article covers LR Optics in great detail PRACTICAL LONG-RANGE RIFLE SHOOTING - PART II: OPTICS

 

[KTDLS7]

The picture is great.
I am looking for more clinical type of information.
What about the amount of light that a larger tube diameter can allow thru?
Does the larger body allow for more durable internals? I don't see a lot of wasted space inside the cutaway picture so are the guts of a 1" scope smaller and thinner to allow them to fit?

I am a technical type of guy and would like to understand the differences that would get manufacturers to spend more money coming up with bigger diameter bodies.

If nothing else, is there any difference between the internals on 1" and 30mm scopes or is it just a bigger package holding the same internals?

To quote "clinical type information" . . .
Tube diameter has NOTHING to do with light transmission. Your original question was answered quite well by roggom and tyler02. Restate: Tube diameter allows for more internal movement of the erector (for dialing elevation), and allows a thicker tube wall section (which equates to body strength). Regarding "light transmission", it is based on glass quality, lens coating, objective diameter, and calculated exit pupil.

 

[para1505]

I am glad someone has brought this topic up. It seems that 30mm tubes get the .308 out to 1000yards with 0 MOA bases. The 1" tubes like Nikons Buck master scopes only has enough adjustment to get them to around 500 yards if my memory is right. So my question is how did John Unertl get a 1" tube to have enough elevation to get a .308 to 1000 yards with the USMC scope?

 

[The_FNG]

30mm tubes don't always have more adjustment than 1 inch ones.

 

[para1505]

Then what is the purpose of a bigger tube if 30mm and 34mm tubes do not always have more elevation than a 1" tube?

 

[OpticsPlanet]

Going with 34mm puts you into fewer choices/more expensive for rings. Economy of scale, I would assume.

Mark H.

 

[abadrs]

Diameter is all adjustment. That being said a fixed one one inch tube could have more adjustment than a 30mm scope. This will depend on the cost factor. If all things are the same the 30mm will have more adjustment than one inch and the 34mm will have more than both. However the mounting choices are not only expensive but you have far less choices once you get above the 30mm mark.

 

[tylerw02]

Then what is the purpose of a bigger tube if 30mm and 34mm tubes do not always have more elevation than a 1" tube?

The 30mm will always have more had the same scope been designed with a 1" diameter.

The 1" with more than 30mm is an apples to oranges comparison.

 

[OpticsPlanet]

Its important to note as Tylerw02 has said, 'same' scopes with a 30mm and 1'' diameter, you will have more travel in the 30mm model. A factor that I havent seen brought up yet, and I apoligize if i missed it, is magnifcation.

The same scope, say a NXS from 5.5-22x compared to the 8-32x, the 5.5-22x will have a higher adjustment range. The more magnifcation a scope has in the SAME model line, the smaller the range will be. So when comparing, say, a 1'' 1-4x monarch 3 and a 12-42 nightforce BR, the monarch 3 even though a 1'' tube will have more elvation adjustment because magnifcation is a factor as well. Now, I know these are extremes, but just as examples to show.


Trevor B.

 

[Okie Gordon]

What about the "brightness" that can be seen thru a scope at a given magnification?

Put another way, does the 1" body cut down on the amount of light that travels thru the bell and thru the body over a larger body?

Is there some sort of relationship between the bell diameter and the body diameter that is ideal?
Does a 50mm bell need a minimum size body to transfer all the light?

How does magnification play into all this?

Is there a specific ideal magnification for a given bell dia and/or body diameter that allows maximum light transfer?

 

[OpticsPlanet]

If youre question is light and your want is to maximize light, the answer is glass quality and lens coatings. A large objective will have the ability to "gather more" light, but does not mean a brighter image always. A larger tube diameter does not mean a brighter image. The best way to improve light transmission or have a bright picture to your eye is to go with higher quality glass and lens coatings. This means high end fully multi-coated coatings on quality glass all surfaces.

Tube size is dependent on your needs for elevation and windage travel or durability only. This is what larger tubes give you. A 32mm objective or a 56mm objective dont care if they are on a 1'' or 30mm tube. Wont change the brightness.

tube size- adjustment and strength (same models with higher magnification will have lower adjustment ranges)
objective- ability to gather light
lens and coatings- resolution/ light transmission (brightness), image quality/ abberation(less)/ protection of glass
Magnification- Personal preference on what your application is and what your skill level. (Higher magnifcations have larger objectives to have the ability to gather as much light as possible)

Trevor B.

 

[Opticsspecialist]

unfortunately, there is a lot about optics that cannot be quantifiably measured, for instance, there is no way to measure how the quality of the glass effects performance, it's up for debate. 1 inch tubes are the american standard, 30mm tubes tend to be the European standard, 34mm tubes are the newest edition to the line up as are the larger tubes. as you go up in tube size, you up the potential for greater erector range ie magnification range and also adjustment range. this is pretty basic, but the thing is the best way to choose what is right for you is to pick the features that are important to you, get behind the scopes and try them, because like I said, there isn't a way to measure some aspects of the optics yet, so until then, it's up for your own interpretation and is subjective to your eye sight and opinion. different eyes see and perceive things differently

 

[Cobracutter]

Diameter is all adjustment. That being said a fixed one one inch tube could have more adjustment than a 30mm scope. This will depend on the cost factor. If all things are the same the 30mm will have more adjustment than one inch and the 34mm will have more than both. However the mounting choices are not only expensive but you have far less choices once you get above the 30mm mark.

That is true about less options. However, anything worth owning is availible in 34MM.

 

[E. Bryant]

However, anything worth owning is availible in 34MM.

Hmm - so a Nightforce F1 is not worth owning. Interesting.

 

[Cobracutter]

Hmm - so a Nightforce F1 is not worth owning. Interesting.

Were talking about mounts............

 

[JL]

Its important to note as Tylerw02 has said, 'same' scopes with a 30mm and 1'' diameter, you will have more travel in the 30mm model. A factor that I havent seen brought up yet, and I apoligize if i missed it, is magnifcation.

The same scope, say a NXS from 5.5-22x compared to the 8-32x, the 5.5-22x will have a higher adjustment range. The more magnifcation a scope has in the SAME model line, the smaller the range will be. So when comparing, say, a 1'' 1-4x monarch 3 and a 12-42 nightforce BR, the monarch 3 even though a 1'' tube will have more elvation adjustment because magnifcation is a factor as well. Now, I know these are extremes, but just as examples to show.


Trevor B.

To be excact, it is focal length that dictates available adjustment range when same dia scopes are compared.
But this does not tell magnification directly as final magnification is dictated by eyepiece focal lenght.

Also, total light transmission depends about lenses (light absortion) and coatings, but also about lens amount- or air-glass transition points. This is challenging to designers as adding lenses solve many problems but effects negatively on transmission. Transmission effects greatly on daylight time contrast as well, not only to twilight performance.

 

[E. Bryant]

Were talking about mounts............

Gotcha. That makes much more sense.

 

[Okie Gordon]

So what is Exit Pupil: 2.8 - 11.8mm & Diopter Compensation: -2 ~ +1 dpr mean?
SWFA SS 3-15x42 Tactical Rifle Scope

 

[BobinNC]

From the article I gave you a link to above.

"The exit pupil is the size of the image coming out of the ocular lens. (Ocular means it's the lens closest to your eye.) If you look at the ocular lens of a scope from a foot or more away, you will see a small area of transmitted light surrounded by black. This is the exit pupil. A larger exit pupil can provide a brighter image to the eye. The maximum size of the human eye's pupil is about 7 mm, so a scope exit pupil larger than that size has no benefit in low light. One advantage of a larger exit pupil not often mentioned is that a larger exit pupil gives more flexibility in eye position to see a full size picture. This is helpful because small head movements do not create the black fringe in the scope view. The other benefit is that it is easier to retain the sight picture through recoil so the shooter can spot his own bullet impacts."

So the exit pupil range on that particular SWFA scope is 2.8MM @ 15X and 11.8MM @ 3x


"Properly adjusting the diopter on a riflescope is something that many shooters, particularly new shooters, misunderstand the importance of. I’ve seen and heard many shooters claim that their scope was broken because they couldn’t get the target image in focus by turning the ocular. In reality though, their scope is probably fine, it’s just that they don’t fully understand how the scope works. By turning the ocular, or ocular assembly, to the right or left, the shooter is increasing or decreasing the distance from ocular to the reticle, in turn focusing it to their eye, nothing more. Some people also mistakenly turn the ocular all the way in when adjusting the diopter and calling it good because the reticle looks sharp, when it’s really not optimal. The user should only adjust the diopter to the point the reticle is nice and crisp against a light background, even when turning away and looking back through the scope. Also keep in mind that the diopter setting will be different from person to person since no two eyes, even in the same skull, are the same." Link Shooting Voodoo :: Anatomy Of A Tactical Bolt Action Rifle: The Riflescope

-2 ~ +1 means the range of diopter adjustment

 

[distantfoe]

I would think there would be a field of view advantage with larger tube scopes.

 

[tylerw02]

I would think there would be a field of view advantage with larger tube scopes.

Your thinking would be incorrect.

 

[allen200]

seeing tons of 30mm now days

 

[Cartman]

Okie, since you asked about it about three time I suspect you know someone who told you a wider tube let in more light. The myth of a wider tube equaling more light coming through is spread everywhere. A while back I was reading some gun rag and a hunting writer named Craig Boddington, if I remember correctly, talked about a scope letting more light through in dim light due to the wider main tube. From the know-it-all at the range, to gun store counter man, to gun magazines, it's a wonder anyone at all knows what's what. What first brought me to the hide vis-a-vie other shooting forums was the high percentage of people who actually understand what they're talking about.

 

[tnichols]

Okie, since you asked about it about three time I suspect you know someone who told you a wider tube let in more light. The myth of a wider tube equaling more light coming through is spread everywhere. A while back I was reading some gun rag and a hunting writer named Craig Boddington, if I remember correctly, talked about a scope letting more light through in dim light due to the wider main tube. From the know-it-all at the range, to gun store counter man, to gun magazines, it's a wonder anyone at all knows what's what. What first brought me to the hide vis-a-vie other shooting forums was the high percentage of people who actually understand what they're talking about.

I couldn't agree more. Well said.