Home Forums Hunting & Shooting Hunting Optics 30 mm vs 1"

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They aren't real common, but the Kahles KX-i and Meopta MeoPro 3.5-10x44/4C are a couple of one-inch illuminated offerings that come to mind.

Advantage:
Stronger tube, more robust.
Adjustment range is typically larger than in 1" tubes, although not always. (This can be relavent even if one does not plan to dial firing solutions.)
Until relatively recently, 30mm tubed scopes were of an overall higher quality optical system...Zeiss, Swaro, Leica, S&B, etc.

Disadvantages:
Prices are typically higher
Weight can be if one is trying to keep overall weight at an anorexic level.

The Campfire always continues to amaze:

There are plenty of 1" illuminated-reticle scopes, and have been for years.

There have been plenty of 30mm scopes in all price ranges for quite a while, so no 30mm scopes aren't brighter because the optics are higher quality. (As a side-point, 30mm scopes got the reputation of being brighter became an advertising agency decided to sell the myth that they "transmit" more light through the larger tube back in the early 1990's. Back then this had a kernel of truth, because the scopes the advertising was promoting wre made by a high-quality Euro-company.)

Ease of "getting behind" a scope depends on the exit pupil and eye relief, which combine to create the "eye box." These have nothing to do with the size of the tube.

Many Euro-scopes used 30mm tubes because that's the standard size they settled on. In America we settled on 1".

I think a 30 looks better on a rifle.
Like a little meat on the bone if ya know what I mean.....

Maybe I wasn't clear enough: for those who think a 30mm tube is brighter/transmits more light, take two SIMILAR optics and compare them. Take a Summit and a Klassik in similar configurations and compare them. You'll "see" similar performance from both in terms of "brightness." The 30mm does not have an advantage.

So, no, 30mm tubes don't transmit more light. And John, yea, cheap 30mm scopes are out there and have been for years -- certainly not in great quantities but out there nonetheless. When most folks think of 30mm scopes, Zeiss, Swaro, S&B, Kahles and Meopta likely come to mind. Barska is likely not the first thing they thought of LOL...

I never said ALL 30mm scopes have superior optics in comparison to 1" offerings (yep, the 'fire amazes me, too ). My statement, in fact, was due to numerous folks making apples-to-oranges comparisons. It stands to reason if they claim to have actually seen a marked difference that they have compared scopes of varying optical qualities, another reason for my comment. Think about it for a moment: Had they compared a 1" Simmons 8-point to some $29 clamshell scope with a 30mm tube, they likely wouldn't be making the erroneous claim.

Recently, on another forum, someone made the "30mm scopes transmit more light" argument because he had used nothing but Vari-X IIs for years and suddenly looked through a VX-6. Similar comparisons have been made here -- and in error, I might add.

No one has mentioned the first plane reticle common in the Euro 30 mm scopes. The reticle size stays the same size in relation to the target which they tell me is some advantage in helping judge distance. Frankly that very large appearing cross-hair irks me a little in my 2.5-10x42 Swarovski in the higher power settings. Those European hunters get to hunt way longer into the evening than we typically can here and I wanted a very good light gathering scope, which it is, but due more to the coating on the lenses than the 30 mm tube size. My little 1" tube Leupold 1.5-5x20 Vari-X lll with the heavy Duplex comes in a very close second as a low light scope which surprised me. Not being able to see the standard cross-hair against an early morning deer with a Leupold 2.5-8x36 had me looking for something better.

I apologize for not being specific in my response earlier.

Mule Deer explained it. There is not more light coming through for scopes with the same objective size and power in regard to the exit pupil. Differences in glass quality and coatings (and number of lenses) may allow a higher percentage of light to pass through but the exit pupil size is the same (same power and objective size). It's not a water hose where a bigger tube allows more water through than a smaller tube. As Mule Deer mentioned, the eye relief (especially coupled with a generous exit pupil) make some scopes easier to get behind...but again, it's not the tube size.

Thanks. I'm not sure but I think I'd heard some argument for a smaller action diameter (bolt action) with the same wall thickness being stronger than a larger one with the same thickness. Even then, I'd guess the strength would be measured to standing up to internal pressure, not external like a scope....but I could be mis-remembering....again... grin Thanks again.

It depends.

There is a ratio of wall thickness to tube diameter that determines the strength of the tube. Aircraft manufacturers and such have it figured out, including space the tube occupies and it's weight.

Given the same wall thickness, I would think the difference between 1" vs 30mm would be negligible in a practical way for scopes.

I had no idea. Checking them out now.


Okie John

With all due respect to your knowledge and experience, I have to slightly disagree.

As I said, considering the same glass quality, same magnification, eye relief etc: (let's say two 2-10x50 scopes), comparing one-inch tube and 30mm tube, it will always be easier to get behind the larger scope simply has more viewing.

1 inch (25.4mm) = A≈20.27
30mm = A≈28.27

as you can see, the 30mm scope has almost 40% more see-through space over one-inch tube so clearly, it will always be easier to get behind the bigger scope.

Same for the light coming through the scope, considering everything else is the same, there will be a more light coming through the larger tube whether your eye can notice it or not. This is not my opinion, this is just pure physics.

Obviously, not all optics are built equal and you can find high-quality one-inch scopes and junk quality 30mm scopes but as I stated in my first post, for my personal use, high quality 30mm scope would provide some benefit over the same quality one-inch scope.

So for those not seeing any benefit by going with anything larger than a one-inch tube, that's fine with me.

30-30 rifles with iron sights killed more game than all the 30mm scopes combined so if that is what works for you keep using 30-30, or one-inch scopes ... or iron sights.

A stream of light doesn't pass through a rifle scope like a water hose. Read and study a bit.

Simple image below, but pay attention to the size of the stream of light coming out of the scope. It has nothing to do with tube size. Think objective size and power/magnification.

I have done enough reading and studying in my life and made living based on math/physics/programming so if you personally don't have a basic knowledge of physics/science, please do not assume that everyone else is clueless about those things.

And while bigger may not always be better, there is a reason why those leading manufacturers are using bigger tubes even for lower magnification scopes that do not need much elevation adjustments.

Anyway, just call Nightforce and they will explain to you why they don't make any one-inch scope since based on your expertise there is no benefit to larger tubes.

Again, since you don't get it. Same objective size and magnification size scopes compared, a larger tube will provide more light and viewing space. I know it may be hard to understand for non-technical people but it is what it is.

Sorry, I can only bring a horse to a water ... but some won't still drink it.

It's been explained and simplified to pictures......believe as you will.

Do you have a PhD or Masters in Optics? If so what school did you go to?

So now I need a PhD or a Master in optics? Hahaha, you don't need a PhD in optics to understand the basics.

You are all arguing and insulting but none of you won't provide anything to prove me otherwise. Just stick to your iron sights, its fine with me.

No, it is not. Well, it is physics, but you've got it wrong. From what you've described, it doesn't sound like you even know what's inside a scope or how they work.

Larger objective lenses do transmit more light. Larger tube diameters do not.

I have both, both are great!!