30mm vs. 1” scope tubes?

CoElkHunter

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I have 1” scopes on all of my rifles for the hunting I’ve done in North America forever. I’ve read here a lot where 30mm tubes are recommended? Are they worth the extra weight and/or better for lower powered scopes? I’m asking because I have a .375 and .416 I’m wanting to put scopes on. Thanks!
 

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CoElkHunter - I am finding as I put scopes on rifles for Clients that the VX-Freedom line from Leupold has made their firedot scopes (3-9x40 and 1.5-4x30) in this line in 30mm - not sure if that is a quirk or intentional design.
 

CoElkHunter

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CoElkHunter - I am finding as I put scopes on rifles for Clients that the VX-Freedom line from Leupold has made their firedot scopes (3-9x40 and 1.5-4x30) in this line in 30mm - not sure if that is a quirk or intentional design.
Well I’ve been looking at Vortex Viper scopes in 30mm on Midway for about $250 on sale. Not an illuminated reticle, but have never needed one before? When you get to a 44-50mm objective, is the illuminated reticle absolutely necessary AND is the increased weight with a 30mm tube necessary? I’m thinking (dangerous) with say a 24-36 mm objective, both the 30mm tube and illuminated reticle might be a better choice? Don’t know, never had either? Thanks!
 

Bert the Turtle

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Thanks! But again, the advantage of the 30mm vs. 1”? I have a 2.5x10x 44mm (1” tube) on my Browning .338. Has worked well for many years.
Fair enough, I didn’t answer the question. Per Swarovski:

A scope's EP corresponds to your own pupil, which dilates from about 2mm in bright sunlight to perhaps 7mm in the dark. If your scope's exit pupil is smaller than your pupil, it can't transmit all the light you can use. If it's larger, the extra rim of light bounces off your iris and never enters your pupil to stimulate your retina. Wasted light. But an excess diameter of exit pupil does give your eye more room to wander around in without showing edge blackout, so that's something.

The reason a 30mm main tube scope isn't inherently brighter than a 1-inch scope is because both carry internal lenses much larger than 7mm, so there is no loss of light through either. The reason some 30mm scopes appear to project brighter views is probably because they were built with the absolute finest materials and effective light transmission (how much light the scope passes through) determines brightness, is a product of the number of air-to-glass surfaces in the scope (the fewer the better) and the anti-reflection coatings on those lenses. (The more the better.)

So what, then, are the advantages of a 30mm scope tube? The walls can be made thicker for added strength and durability or the internal lenses can be made slightly larger, which increases optical performance simply because larger lenses always perform better than smaller ones, all else being equal. Alternatively, manufacturers can keep internal lenses the same size as those in their 1-inch scopes and use the extra internal room for long range reticle adjustments.



2.5-10 is totally appropriate for a 338 but I think it is a bad choice for a 375 or a 416 unless it will be used exclusively on plains game or the scope will be removed for close in work, assuming one has time. True 1x allows best performance of a scope up close.
 

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Just a heads up, the Vortex lower level scopes are made in China, i.e. junk. But hey, they have a great warranty! When it goes tits up in Africa, you'll be able to get it fixed when you get back.:E Laugh:

Seriously, 30 & larger tubes generally allow more adjustment. For example, the Nightforce NXS line has 100 moa of elevation and 60 moa of windage.
 
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CoElkHunter

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Fair enough, I didn’t answer the question. Per Swarovski:

A scope's EP corresponds to your own pupil, which dilates from about 2mm in bright sunlight to perhaps 7mm in the dark. If your scope's exit pupil is smaller than your pupil, it can't transmit all the light you can use. If it's larger, the extra rim of light bounces off your iris and never enters your pupil to stimulate your retina. Wasted light. But an excess diameter of exit pupil does give your eye more room to wander around in without showing edge blackout, so that's something.

The reason a 30mm main tube scope isn't inherently brighter than a 1-inch scope is because both carry internal lenses much larger than 7mm, so there is no loss of light through either. The reason some 30mm scopes appear to project brighter views is probably because they were built with the absolute finest materials and effective light transmission (how much light the scope passes through) determines brightness, is a product of the number of air-to-glass surfaces in the scope (the fewer the better) and the anti-reflection coatings on those lenses. (The more the better.)

So what, then, are the advantages of a 30mm scope tube? The walls can be made thicker for added strength and durability or the internal lenses can be made slightly larger, which increases optical performance simply because larger lenses always perform better than smaller ones, all else being equal. Alternatively, manufacturers can keep internal lenses the same size as those in their 1-inch scopes and use the extra internal room for long range reticle adjustments.



2.5-10 is totally appropriate for a 338 but I think it is a bad choice for a 375 or a 416 unless it will be used exclusively on plains game or the scope will be removed for close in work, assuming one has time. True 1x allows best performance of a scope up close.
Thank you for explaining this!
 

CoElkHunter

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Just a heads up, the Vortex lower level scopes are made in China, i.e. junk. But hey, they have a great warranty! When it goes tits up in Africa, you'll be able to get it fixed when you get back.:E Laugh:

Seriously, 30 & larger tubes generally allow more adjustment. For example, the Nightforce NXS line has 100 moa of elevation and 60 moa of windage.
Good points! I guess I just have a difficult time looking at buying a scope that costs at least twice what I paid for my rifle? Guess I’ll have to shop around for a good quality used scope.
 

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Here’s one from Midway USA. On sale, it’s almost three times what I paid for my rifle! Come on guys!
 

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Here’s one from Midway USA. On sale, it’s almost three times what I paid for my rifle! Come on guys!

I shopped around on the Leupold VX6-HD 1-6 and found it for $899. It’s a great scope and I have two of the 2-12 in this same series on other rifles. Worth looking into IMO
 

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Good points! I guess I just have a difficult time looking at buying a scope that costs at least twice what I paid for my rifle? Guess I’ll have to shop around for a good quality used scope.
You can get a inexpensive rifle to shoot pretty well. But a cheap piece of optics won't let you see well enough to hit what you want. If you look at the what the benchrest and Fclass shooters use for glass you will find that the glass cost more than the rifles they are using. The first time you use good glass you will ask yourself why did I accept less on my rifles. The detail you can see in low light has to be seen to believe. and the Bino's and spotting scopes also fall in this school of thought.. One year elk hunting I had the best bino's I ever owned ($200 Leopold)and my buddy had me hold his swarovski's whhile he made a shot. Since I had his in hand I was going to spot for him and I was SO VERY SURPRISED at the difference in what I was seeing. I can emphasis enough to buy the best glass you can afford, save for a while you won't regret it.
 

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For what it's worth - asked our PH about mid-tier brands Nikon, Vortex, etc. vs. high-end scopes Swarokski, Zeiss, etc. - what did he recommend? His response was a good quality mid-tier scope was fine for PG safari. Yes, he had Swarovski & Zeiss, but because he needed a dependable in all circumstances scope - bang around in the rover, drop it, pick it up, and know it will stop dangerous game in one shot. So in his opinion top tier scopes for PG not necessary - just bring a good quality scope that you have confidence in and shoots accurately. For DG spend the dollars.
 

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Good points! I guess I just have a difficult time looking at buying a scope that costs at least twice what I paid for my rifle? Guess I’ll have to shop around for a good quality used scope.
We have all been there. You will enjoy the clarity and brightness of a quality scope. You will only appreciate it when you get back behind a scope of lesser quality and compare.
Budget rifles are mostly accurate enough for hunting. Better rifles improved accuracy , smoother action and reliability.
@Bert the Turtle explained a lot. Ive read the pros and cons but this puts it into context for the hunter.
I have a couple of decent scopes and used better scopes but i aldo started with cheap stuff and need better scopes as my eyes deteriorate and im only 48
Lieca get mentioned a lot here and some S&B, i havent used these but they are probably at the higher price point. Im not sure where the best value point is but i probably would not go less than a Leupold
 

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Why a 30 mm tube on scopes with objective bells...

The 30 mm tube choice has nothing to do with light transmission. The only advantage a 30 mm tube has over a 1" tube on a scope with an objective bell, is that it allows more room internally for a wider range of adjustment of the scope erector, i.e. the mechanism that holds the reticle:
  • The reason why European scopes standardized at 30 mm instead of 25 mm is that in days when the tolerances on the mounting of scope bases were much looser than today, a 30 mm scope generally had enough internal adjustment to avoid having to shim the bases and/or the rings. 25 mm scopes often needed external adjustment in addition to internal adjustment. A definite weakness...
  • The reason why virtually all modern military scopes have 30 mm tubes is similar, but applied to a different purpose. More internal adjustment allows more elevation clicks to shoot farther.
  • The reason why some military scopes are now available with 34 mm tubes is more of the same: more internal elevation clicks for latest longer range loads (e.g. Lapua, etc.).
Why a 30 mm tube on scopes without objective bells...

First we need to explain a little more the exit pupil concept. Yes, human pupil vary in diameter from 2 mm to 7 mm, but the application of this fact has nothing to do with the tube diameter, because indeed whether the tube be 25 mm, 1" (25.4 mm), 30 mm or 34 mm is irrelevant to a 7 mm light beam. Bert the Turtle is correct!

The application of the basic rule that a 7 mm light beam must desirably reach the pupil at full dilatation in low light condition applies to the diameter of the objective. The basic rule is that magnification x light beam diameter determines the diameter of the objective. This is the reason why most European x6 scopes have a 42 mm objective (6x 7mm = 42 mm), most European x8 scopes have a 56 mm objective (8x 7mm = 56 mm), etc.

This is the reason why a straight 1" tube DG scope with 20 mm objective on a .375 H&H rifle that may see yeoman service on a 1 rifle safari involving early or late shooting, is not ideal. Regardless of glass quality, a 1.5-4x20 straight tube 1" scope only produces a 5 mm light beam at 4x (20 / 4 = 5). This typically means 5 to 10 less minutes of shooting light at dawn or dusk, and that may make all the difference in the world, where legal...

Everything else (such as glass and coatings quality) being equal, you will factually see a Leopard at dusk, or a Kudu at dawn, better with a 42 mm objective than with a 20 mm objective because a 42 mm objective will collect a 7 mm light beam at 6x and a 20 mm objective will only collect a 5 mm beam at 4x. The best glass in the world, from whichever manufacturer, will not make up for this. Period.

A straight 30 mm tube DG scope with 24 mm objective is a step in the right direction. At 4x a 24 mm objective gives you a 6 mm light beam. This is not as good as 7 mm, but this is appreciably better that 5 mm.

I personally play the game on both ends: I use a 30 mm straight tube because of its 24 mm objective, and I rarely use it at more than 3.5x because it produces a 7 mm light bean at that magnification, and anyway I do not shoot far in general when I use a DG rifle... and anyway I am incapable of seeing a difference between 3.5x and 4x... and anyway any variable optic from any manufacturer will typically not have the best image quality at max power...

Please note that all these considerations disappear when using the scope in full day light when a younger shooter pupil is shrinking to 2 mm and an older shooter pupil is shrinking to 3 mm. This is why a modern straight tube scope with a lot of magnification still makes some level of sense. It would be a gross misuse of a Z8i 1-8x24 to try to use it at 8x at dawn or dusk because its 3 mm beam would not even carry half the light the shooter could use and would need, but at high noon this 3 mm beam would work just fine. Although why one would want 8x on a DG rifle scope escapes me...

In summary:
  1. A 30 mm tube provides a wider internal adjustment range, which may solve a less than perfectly aligned scope mount issue, and which allows more internal elevation clicks, useful for long range shooting;
  2. On straight tube scopes a 30 mm tube provides a larger objective diameter over a 1" tube (typically 24 mm over 20 mm), which increases the diameter of light beam reaching the shooter's eye at any magnification considered.
 
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Hogpatrol

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One can find good deals on other forums' classifieds and sometimes on ebay. Some of us buy a scope, find we don't like it and then put it on the sale or auction block just to get rid of it. I picked up a lightly used Trijicon 5-20 for less than $700 on ebay and it's a worthy scope for a PG or U.S. big game hunt.
 

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30mm 1-6 or 1-8 HD glass for those rifles, brand is a more personal choice. Hard to beat the Leupold VX6-HD 1-6 for the money, but the Swarvo Z8i 1-8 is definitely top dog in this class, IMHO

I have both of those scopes and totally agree with you. The only knock on the Swaro is that is has significantly less windage and elevation adjustment than the Leupold.
 

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Why a 30 mm tube on scopes with objective bells...

The 30 mm tube choice has nothing to do with light transmission. The only advantage a 30 mm tube gives over a 1" tube is that it allows more room internally for a wider range of adjustment of the scope erector, i.e. the mechanism that holds the reticle:
  • The reason why European scopes more or less standardized at 30 mm instead of 25 mm is that in days when the tolerances on the mounting of scope bases were much looser than today, a 30 mm scope generally had enough internal adjustment to avoid having to shim the bases and/or the rings. 25 mm scopes often needed external adjustment in addition to internal adjustment. A definite weakness...
  • The reason why virtually all modern military scopes have 30 mm tubes is similar, but applied to a different purpose. More internal adjustments allow more elevation clicks to shoot farther.
  • The reason why some military scope are now available with 34 mm tubes is more of the same: more internal elevation clicks for latest longer range loads (e.g. Lapua, etc.).
Why a 30 mm tube on scopes without objective bells...

First we need to explain a little more the exit pupil concept. Yes, human pupil vary in diameter from 2 mm to 7 mm, but the application of this fact has nothing to do with the tube diameter, because indeed whether the tube be 25 mm, 1" (25.4 mm), 30 mm or 34 mm is irrelevant to a 7 mm light beam. Bert the Turtle is correct!

The application of the basic rule that a 7 mm light beam must desirably reach the pupil at full dilatation in low light condition applies to the diameter of the objective. The basic rule is that magnification x light beam diameter determines the diameter of the objective. This is the reason why most European x6 scopes have a 42 mm objective (6x 7mm = 42 mm), most European x8 scopes have a 56 mm objective (8x 7mm = 56 mm), etc.

This is the reason why a straight 1" tube DG scope with 20 mm objective on a .375 H&H rifle that may see yeoman service on a 1 rifle safari involving early or late shooting, is not ideal. Regardless of glass quality, a 1.5-4x20 straight tube 1" scope only projects a 5 mm light beam at 4x (20 / 4 = 5).

Everything else (such as glass and coatings quality) being equal, you will factually see a Leopard at dusk, or a Kudu at dawn, better with a 42 mm objective than with a 20 mm objective because a 42 mm objective will collect a 7 mm light beam at 6x and a 20 mm objective will only collect a 5 mm beam at 5x. The best glass in the world, from whichever manufacturer, will not make up for this. Period.

A straight 30" tube DG scope with 24 mm objective is a step in the right direction. At 5x a 24 mm objective gives you an almost 5 mm light beam. This is not as good as 7 mm, but this is appreciably better that 4 mm.

I personally play the game on both ends: I use a 30 mm straight tube because of its 24 mm objective, and I rarely use it at more than 3.5x because it gives a 7 mm light bean at that magnification, and anyway I do not shoot far in general when I use a DG rifle...

Please note that all these considerations disappear when using the scope in full day light when a younger shooter pupil is shrinking to 2 mm and an older shooter pupil is shrinking to 3 mm. This is why a modern straight tube scope with a lot of magnification still makes some level of sense. It would be a gross misuse of a Z8i 1-8x24 to try to use it at 8x at dawn or dusk because its 3 mm beam would not even carry half the light the shooter could use and would need, but at high noon this 3 mm beam would work just fine.

In summary:
  1. A 30 mm tube provides a wider internal adjustment range, which may solve a less than perfectly aligned scope mount issue, and which allows more internal elevation clicks, useful for long range shooting; AND
  2. On straight tube scopes a 30 mm tube provides a larger objective diameter over a 1" tube (typically 24 mm over 20 mm), which increases the diameter of light beam reaching the shooter's eye at any magnification considered.
Thanks so much One Day for explaining this! So, for a low magnification straight tube as used for DG, a 30mm tube would be best. But for my .375, I could use a 2.5-10 x 44 (or 50) as I have been using for years in a 1” tube on my .338 and there would be no handicap as far as low light shooting goes compared with a 30mm tube? I generally hunt elk in/next to heavy timber and have never had an issue with not being able to see an animal through the scope in low light conditions AND without a lighted reticle! Maybe the heavy timber in Africa is more dense?
 

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