1" vs 30mm light transmission?

palmer_mike

Well-Known Member
I'm shortly going to be looking for a new scope and have narrowed the field to a handful of different options... One of these being a Swaro z3. This scope has a 1"tube, will this mean the scope will be less good at dawn/dusk than a 30mm tubes scope or will the difference be negligible?
 
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Many get mixed up between tube size and light transmission. It makes no odds. What matters FAR more is scope design (ie nr of lenses and whether fixed or variable), lens quality, whether apochromatic or non apo lenses are used, lens coating quality and ratio of objective to ocular lens. The eye benefits from the brightest image when the objective to ocular ratio is about 7. Any decent glass should perform well form between about 4.5 to 5 though. Above 7, the eye doesn't benefit from the full lens image. If you check out specifications such as light transmission, and to what extent the lens groups have been coated, that matters more than tube diameter. Basically, 30mm tube sizes are there to allow more movement for the erector tube assembly to allow greater adjustment, something that longer range target shooters benefit from as it allows better flexibility for dialled in fire solutions without the need perhaps to use an adjustable mount.

Prime lenses (ie non zooms) will always offer better resolution and light tramsmission than zoom lenses, so a mediocre 1" fixed scope of say 6 x 42 will usually outperform a more expensive 30mm tubed zoom scope.
 
It is the premise of the OP question which is curious.

I have a Z4i and it has a 30mm tube.

The Z4i with the 56mm objective lens should be better than most at dawn and dusk.

Alan

oops sorry I meant z3, I'll ammend the op. It's the Z3 4-12 x 50 I'm looking at. I currently have a duralyt 3-12 x 50 on another rifle........
 
I'm not familiar with the Z4i but the tube size won't make a difference to light gathering. The size of the objective lens will. Basically a larger objective combined with a lesser magnification is the best combination (for light gathering). The greater the twilight factor the better.

Courtesy of Zeiss:

The twilight factor makes it possible to compare the performance of binoculars and scopes in low -light conditions. It is calculated by first multiplying the magnification by the objective lens diameter and then finding the square root of the result. In a 7x42 binocular, the twilight factor is therefore 17.2 - the minimum for sufficient detail recognition in twilight - and an 8x56 binocular has a twilight factor of 21.2. A comparison: An 8x30 binocular, on the other hand, has a twilight factor of 15.5 and is therefore less suitable for viewing in very low light conditions.

so perhaps the answer could have been better
 
There is however the proposition of a preferred esthetic to be considered here and I'd be the first to concede the larger tube can, when suitably mounted both in terms of rings and height above action/chamber, look far more 'planted' as does a Land Rover with wider than standard tyres. This being particularly noticable when a 56mm objective blossoms from a circa 1" tube.

This properly doesn't help Palmer Mike though!


K
 
This is true - on both points, aesthetics and not helping Palmer Mike

A properly proportioned 1" scope fitted to a classic hunting rifle is a thing of elegance. A lump of 30, 34 or even 35mm is very much out of place in that context. However, each to his own and I admit to owning most variants.
 
This is true - on both points, aesthetics and not helping Palmer Mike

A properly proportioned 1" scope fitted to a classic hunting rifle is a thing of elegance. A lump of 30, 34 or even 35mm is very much out of place in that context. However, each to his own and I admit to owning most variants.

I should have simply said a 56mm objective looks less incongruous when coupled to a 30mm tube but I take your wider point.

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K
 
Chester P is quite right the 30mm tube does not carry more light, but it isn't there for that reason.
A greater diameter tube allows for greater elevation for those really long shots.
Tactical scopes have been getting wider; because the range of sniper and squad support rifles have been getting longer and longer.
So the choice is yours; lighter scope with the same light transmission (given the objective is the same dia) but limited to say 700m or a heavy scope with the same light transmission but the ability to wind up to 1000m+ without resorting to a special base (+big cost penalty usually).
 
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I'm shortly going to be looking for a new scope and have narrowed the field to a handful of different options... One of these being a Swaro z3. This scope has a 1"tube, will this mean the scope will be less good at dawn/dusk than a 30mm tubes scope or will the difference be negligible?

The difference may be measurable with instruments but certainly not noticeable to the human eye. So the difference exists mainly in the eyes of the marketing men who are looking to differentiate their products so they can charge more.
 
The difference may be measurable with instruments but certainly not noticeable to the human eye. So the difference exists mainly in the eyes of the marketing men who are looking to differentiate their products so they can charge more.

Thats what I was hoping!
thank you
 
A 30mm tube can be made with thinner wall material than a 1" tube while also being stronger, so depending on tube length a wider 30mm scope can actually be lighter than a thinner tube of the same or less strength/rigidity.
 
At the end the light has to be bundled down to 7mm or less to be get into the eye. I don't think we'll notice a difference between 25mm or 34mm tube. My 1" Zeiss is optically just as good as my 34mm tactical Kahles.
edi
 
This is true - on both points, aesthetics and not helping Palmer Mike

A properly proportioned 1" scope fitted to a classic hunting rifle is a thing of elegance. A lump of 30, 34 or even 35mm is very much out of place in that context. However, each to his own and I admit to owning most variants.
I love them, on the 1903 Springfield, on the M1 Garand, and on vintage sporting Mausers. Don't underestimate them. I use a 2.5x Lyman Alaskan in QD Paul Jaeger mounts over a Redfield receiver sight - Redfield zeroed at 175 yards now and scope at 300 yards. This Mauser stutzen below is not mine, alas!
1903A3-lyman-alaskan.jpgjpsauer-mauser-3006-G&Hmount-Lyman-alaskan.jpg
 
The difference may be measurable with instruments but certainly not noticeable to the human eye. So the difference exists mainly in the eyes of the marketing men who are looking to differentiate their products so they can charge more.

This is incorrect... the bigger the tube the greater the reticule movement that becomes available, also the greater the zoom range possible... you simply couldn't have the 100 clicks available on say the Zeiss V8with a 1" tube.. Having a nice big diameter tube also means the scope can ne made shorter as it allows the lens element array to be utilised more efficiently... it also helps to prevent tunnelling!

Can't think of anything else right now but pure marketing hype it ain't!
 
A larger tube is simply no guarantee of better optical quality. It may allow more adjustment but the ocular image projected has to be 7mm for optimum sight picture and brightness. For all intents and purposes, a one inch tube with decent glass will always better a 30mm tube (or larger) with poorer glass. There are pros and cons for each but the primary reason for larger tube sizes was originally for a wider range of adjustment and not better optical clarity. Tunnelling is only a real issue for wider magnification scopes, and high power zooms are not necessary for deer stalking or generally for hunting in the UK. Most shots, even on small game, can be accurately taken out to 200 yards with a 10 times magnification, and that's unlikely to suffer from the tunnelling effect on anything but a poorly designed scope. Vignetting or tunnelling is usually a function of eye relief and reduced field of view, and the lens cluster design (breadth of clear image obtained from the objective at higher magnification). A 30mm scope is not immune to vignetting issues.

I use both one inch and 30mm optics but my primary reason for using the 30mm scope is to allow for a greater adjustment range for target work on some of my rifles.
 
Larger lenses are easier to put together without distortion, but the are all pretty darn good. There are more factors in light transmission ( presumably for shooting in bad light ), than just area of glass.
- glass quality
- grinding
- coatings
- matching lenses
- true coloration
- resolution

I have a 1.5-6x42mm 30mm tube scope with 91% light transmission. I have, and have had, 35mm and 36mm 1-inch scopes with 95% light transmission, which looked very bright. What that 30mm does have is huge field of view and 5-inch eye relief, which makes it great for fast shooting at driven or charging game in the woods, especially on a .444 or .375 H&H.

A high quality scope with terrific resolution and true coloration, like a Swaro 3-9x36mm, will let you see detail in poor light which a larger scope with less resolution will not. You cannot just compare them on paper. You need to compare them in the various light in which you shoot, on your rifles, and on the game animals in that light, with their hair.
 
Larger lenses are easier to put together without distortion, but the are all pretty darn good. There are more factors in light transmission ( presumably for shooting in bad light ), than just area of glass.
- glass quality
- grinding
- coatings
- matching lenses
- true coloration
- resolution

I have a 1.5-6x42mm 30mm tube scope with 91% light transmission. I have, and have had, 35mm and 36mm 1-inch scopes with 95% light transmission, which looked very bright. What that 30mm does have is huge field of view and 5-inch eye relief, which makes it great for fast shooting at driven or charging game in the woods, especially on a .444 or .375 H&H.

A high quality scope with terrific resolution and true coloration, like a Swaro 3-9x36mm, will let you see detail in poor light which a larger scope with less resolution will not. You cannot just compare them on paper. You need to compare them in the various light in which you shoot, on your rifles, and on the game animals in that light, with their hair.

All good points. I'm in the middle of putting together a review on a range of scopes and will be measuring resolution at 100m in various light conditions for exactly the reasons you mention. Paper specs are only ever half the story with anything. Practical application is needed to conclusively place what makes a good scope for a given purpose. Optically, I have several scopes all of which perform similarly in daylight, showing equal brightness and resolution. However, show them the twilight and then pitch black and a gulf of difference opens up between them irrespective of paper specs, largely because resolving power in bad lighting conditions showcases the better optics. Coating systems vary quite a lot. Many of the better lenses all come out of the same factory (Hoya), so what separates Leup from say a top budget manufacturer will be the coatings, grind and scope lens group design.
 
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