Does the 30mm scope tube offer a better field of view than 1 inch scope tube? Is there any advantage?

Nope, the FOV is largely determined by 1) magnification and 2) construction of ocular end of the scope.

For umpteen years, 30 mm tubes allowed the zoom factor to be as high as 4x (e.g. 1.5-6, 2.5-10 or 3-12) whereas a 1" tube only allowed allowed a zoom factor of 3x (e.g. 3-9, 4-12 etc). There are people who claim a 30mm tube also allows more vindage and elevation adjustment, but whether this is true or not, I don't know.

These days, zoom factors are increasing (Swaro offer 6x or 5x zoom factors etc). I don't know if the connection between zoom factor and center tube diameter is as simple and strong as it used to be.

- mike

VX-3 1.5-5x20mm - 25 mm tube - FOV= 68' and elevation adjustment = 120 MOA
VX-3 1.5-5x20mm Illum. Reticle - 30 mm tube - FOV= 66.5' and elevation adjustment = 120 MOA

Warrior

The 30mm tube is very useful if all you have is 30mm rings. Also, in the event that the scope fails completely, the larger tube provides a better grip when using the scope as a club.

Manufacturers could theoretically utilize the larger tube diameter to provide a greater range of internal adjustment. However, as Warrior points out, they choose not to.

1) Leupold VX-3 4.5x14 1 inch tube MOA adjustment 71 x 71

2) Leupold VX-3 Long Range 4.5x14 30 MM tube MOA adjustement 116x116

30mm offer a mounting advantage on scopes with a large (>50mm) objective.

quote:

Originally posted by Rub Line:
30mm offer a mounting advantage on scopes with a large (>50mm) objective.

Elaboration would be appreciated.

30mm scopes were used for years in European optics because they're on the metric system. US companies are now copying them, just as European scope companies had to make 1" tubes to sell in volume over here. I once owned an ancient 30mm rail mounted scope for a drilling.

The main advantage for 30mm scopes is for the optics companies to find a new way to get into our wallets without offering any real tangible benefit to 99% of shooters. More power to them if people are willing to pay.

There should be some benefit to light transmission, internal adjustment (windage and elevation on the "erector set").

For some people there's a perceived "cool guy" advantage to buying a 30mm scope.

quote:

Originally posted by Stonecreek:
Manufacturers could theoretically utilize the larger tube diameter to provide a greater range of internal adjustment. However, as Warrior points out, they choose not to.

You guys crack me up. About 70% of what is posted above is pure piffle!

Inside the scope tube is a second tube called the erector tube. It generally contains the reticle which can be mounted in the first or second focal plain. The erector tube moves up and down between spring probes and screws for windage and elevation moving the reticle and therefore the point of impact. The larger the internal diameter of the main tube the larger the range variation available to the shooter.

Not only do 30mm tubes give more erector travel, 34mm, 35mm tubes are currently marketed by S&B, US Optics, and others which give significant range capability to the rifle. Makers tend to give up a little travel to allow for a stronger tube.

Here I am with a USO SN-3 with a 34mm tube and with a first focal plain reticle. Note the barrel angle as I try to find a water jug at over 700 yards with my .308. This scope has 95 clicks per revolution on the elevation knob and up to 3 turns of travel. In this case, the click is .2mils, so both reticle and knobs are in metric.



Here is a close up of scope knobs:

I've heard of the "Third Eye" of wisdom but that's the first "Third Ear" I"ve encountered...for price I could make you a custom ear protector set

quote:

Originally posted by tiggertate:
I've heard of the "Third Eye" of wisdom but that's the first "Third Ear" I"ve encountered...for price I could make you a custom ear protector set

Yes, I was discussing the ballistics of the shot with my shooting partner, and while I was talking I moved the ears so I could hear him. He took my picture shortly thereafter, but it shows the hardware fairly well.

And the hardware is stunning. Very nice rifle.

Once again, the only useful characteristic of the larger scope tube is to provide more internal adjustment of the reticle. And once again, as Warrior points out, manufacturers don't always take advantage of that opportunity.

Insofar as scopes for hunting rifles, a tube of larger than one inch is of no advantage. Nor is it of any advantage on target or varmint rifles intended for shooting inside of about 600 yards.

However, sometimes when dealing with the rainbow trajectories encountered in extreme long range shooting (1,000 yards and longer), the typical adjustment available in a one-inch tube may not provide sufficient elevation to allow the crosshair to be level with the target.

Highly specialized scopes for highly specialized rifles can reasonably utilize tubes larger than one inch. But to imply that Bubba can somehow benefit from on 30mm tube on his 4x scope for his .308 Remington pump deer gun would be seriously misleading.

All of a sudden in the new upgrades of various scope brands we get that the eyepieces are made larger - both in length and diameter, as if they don't consider the ideal mounting position on a bolt-action rifles.

One is now forced to go to higher rings and the bolt-handle invariable opens against the thick part of the occular bell instead of just in front of it like the case is with most Leupolds.

That is why I like the eyepieces of the German made Kaps scope that comes in with a diameter of only 39 mm. Most scopes today are coming in at 41 and 43 mm, whilst the new MeoPro comes in at 45 mm.

And another thing ... I always pick scopes with a minimum of 5.4" plus tube length for ease of mounting.

Warrior

Does it make a difference on straigt tube scopes where the front ocular is 1" compared 30mm?

Rich

quote:

Originally posted by richj:
Does it make a difference on straigt tube scopes where the front ocular is 1" compared 30mm?

Rich

What makes a difference is not the outside diameter of the objective housing, but the actual (and effective) diameter of the objective lens. Given that a 30mm tube with a straight (un-belled) ojective can accomodate a larger lens than a 1" objective, then you can increase the exit pupil without utilizing a bell. However, you can get the same effect (and identical barrel clearance) by belling the 1" tube up to the same size as the 30mm tube (about 1.18"). A few manufacturers have offered such small bells, which usually accomodate about a 24mm lens (compared to the appx 20mm lens that a 1" straight tube will accomodate.)

quote:

Originally posted by Warrior:
All of a sudden in the new upgrades of various scope brands we get that the eyepieces are made larger - both in length and diameter, as if they don't consider the ideal mounting position on a bolt-action rifles.
Warrior

Another result of "camera" companies trying to build optical gunsights. A riflescope is not just a telescope with a reticle in it, it must become an integral part of the gun. If it is too bulky, too short, too fat, or has excessively critical eye relief, then it becomes impractical to use as a gunsight, no matter how good its optics may be.

The larger external tube will allow more W&E adjustment range only if the interior tube (and lenses) stays small.

Bruce

quote:

Originally posted by richj:
Does it make a difference on straigt tube scopes where the front ocular is 1" compared 30mm?

Rich

Yes. All else being equal, a 24mm objective lens in a 30mm tube is better than a 20mm objective in a one inch tube.

quote:

Originally posted by Michael Robinson:

quote:

Originally posted by richj:
Does it make a difference on straigt tube scopes where the front ocular is 1" compared 30mm?

Rich

Yes. All else being equal, a 24mm objective lens in a 30mm tube is better than a 20mm objective in a one inch tube.

"Better" in what way? If the magnification is 2.5X, then the 20mm objective yields an 8mm exit pupil, which is well in excess of what the best and youngest of human eyes can utilize (about 7mm is the limit of the pupil dialation).

Even at 4x magnification, a 20mm objective yields a 5mm exit pupil, which is as good as most older shooters ("older" being 40+ or a smoker at any age) pupils will do.

It is true that as magnification goes up that a 24mm objective begins to provide a larger usable exit pupil, but then most straight (non-belled objective) scopes are 4X and under, making the issue somewhat moot. If you wanted a 5X straight-tubed scope, then a 30mm tube with a 24mm objective lens would give you a near-optimal exit pupil of almost 5mm, while a 1-incher with a 20mm objective would limit you to a 3.33mm pupil. So the difference in the two is that a 30mm tube allows (almost) at 5x what a 1-inch tube allows at 4x.

Nice explanation Stonecreek.
This is why the 2-7x scopes go to 33 mm objective bells (to yield 4.7 mm)
The upper magnification should give at least 4 mm, but 5 mm is better.
3-9 x 40 mm scopes yield 4.44 mm
some bigger scopes give less, like 4.5-14 x 50 mm yield 3.57 mm
And so forth.

Warrior

quote:

Originally posted by Stonecreek:
"Better" in what way? If the magnification is 2.5X, then the 20mm objective yields an 8mm exit pupil, which is well in excess of what the best and youngest of human eyes can utilize (about 7mm is the limit of the pupil dialation).

Even at 4x magnification, a 20mm objective yields a 5mm exit pupil, which is as good as most older shooters ("older" being 40+ or a smoker at any age) pupils will do.

It is true that as magnification goes up that a 24mm objective begins to provide a larger usable exit pupil, but then most straight (non-belled objective) scopes are 4X and under, making the issue somewhat moot. If you wanted a 5X straight-tubed scope, then a 30mm tube with a 24mm objective lens would give you a near-optimal exit pupil of almost 5mm, while a 1-incher with a 20mm objective would limit you to a 3.33mm pupil. So the difference in the two is that a 30mm tube allows (almost) at 5x what a 1-inch tube allows at 4x.

Better in the way you have stated.

And mo' bettah besides.

In addition to providing more light transmission, a larger exit pupil can also make it much quicker to line up a shot.

quote:

In addition to providing more light transmission, a larger exit pupil can also make it much quicker to line up a shot.

This is true of a larger exit pupil. However, the eye placement latitiude provided by a larger exit pupil is minimal compared to the influence of other factors.

30mm tubes also seem to be a tribute to illuminated reticles for a large part.
I believe the only scope on the market with illumunated reticles and a 1 inch tube is now made by Kahles. All the rest have 30mm tubes.