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Thread: Difference between 1" and 30mm

  1. #1
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    Difference between 1" and 30mm

    I was reading on another somewhat gun related internet forum... where a person asked this very same question. Naturally, he got all sorts of misinformation, followed by arguing as to who was right and who was wrong... then the thread pretty much turned to crap.

    So... here is what I can tell you for sure. The difference between 1" and 30mm tubs is: 4.6mm, any more than that is pretty much a guess.

    So, let's look at some of the common assertions and beliefs about the 1.00" vs. 30mm battle... which, I believe is discussed largely because the 9mm vs. 40SW vs. 45ACP thing is just so old now.

    The adantage to 30mm is that it offers more adjustment for elevation: Well, it can, sure... but there is another tube inside of the 1" or 30mm external tube, as well as the associated adjustment assembly, and in a lot of cases, scope manufacturers use the same "guts" in a 30mm tube as they do in the 1" tubes. So, just because a scope has a 30mm tube, it does not mean it has more adjustment, but the only way one knows what the adjustment range of a particular scope is, is to get that spec for that scope.

    30mm tubes most likely caught on because they were "European" and associated with high quality scopes, or maybe the "more is better" mindset... American scope companies had to ofer 30mm tubes to compete -- but the smart buyer will check to make sure that the only feature of that 30mm tube scope, is not the 30mm tube.

    30mm Tubes are stronger: Well, again... they could be. But just having a larger outside diameter does not assure that a tube is stronger than a smaller diameter tube... Given the number of scope tubes that I have seen break, this one really does not matter that much to me one way or the other.

    30mm Tubes are "brighter": This one needs to be broke down into a couple of catagories...

    1. A 30mm tubes will/won't pass more light than a 1" tube: This one is silly, but people argue it... of course a 30mm tube will "pass more light" -- to put this in the best "Are you smarter than a 5th grader, home science project" just ask yourself this:

    Imagine you have a little solar panel, one of them things you shine a light on and it makes 'lectricity, and you masked it off so that only a 1" hole was uncovered and put it under a light and recorded the voltage produced.

    Now, you do the same thing, but with a 30mm hole... do you think the voltage would be higher? Course it would, there is more surface on the panel exposed to the same light -- therefore, there is more "light" getting through the larger hole.


    Of course that is a silly example, and not at all the type of light transmission that we deal with in a rifle scope... so, lets look at the real answer.

    Yes, a 30mm tube can be brighter than the same scope with a 1" tube... can be, most likely is, if it is an expensive scope because they will use premium optics, coatings and engineering -- optics, glass and coatings aside, the increased room in the 30mm tube allows for the use of larger Field Lenses, Erector Lenses and other optics in the tube. Larger optics can receive and pass more light. But then you start to give up some of the increased adjustment room, doh!

    If the manufacturer does not use larger lenses inside the tube, then there will be no difference between a 1" and 30mm tube as far as "brightness" goes. If the manufacturer (properly) uses larger internal optics, the scope can be brighter... will you be able to see the difference? That depends on the user, the conditions and the scope.

    30mm Tubes are 4.6mm bigger than 1" Tubes: Yes, that's right! That is one of the fo'sures... also, that the 30mm scope will need 30mm rings! Truth is, a great number of scopes with 30mm tubes are just that... a scope with a 30mm tube, but folks buy them and it sounds cool when you post on the internet that you have one... Not saying that 30mm tubes are bad, as I pointed out, they may in fact offer a superior package inside -- or they may not... caveat emptor.

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    I've not followed the 1" v. 30mm debate elsewhere, but there is some great food for thought here. Of course, being in Europe, I'm far more familiar with high-end German 30mm offerings than most of what's on the domestic market back home. In that sense, K.L. rightly observes that, while the actual tube dimensions definitely factor into all of this, a lot of the difference you're likely to see with a Schmidt & Bender, Zeiss, or Swarovski really has to do with the quality of the glass and coatings used.

    To the German mindset, where most optics are tailored to hunting, and most hunting is done at night, a 30mm tube is a given and the real issue has to do with objective lens/bell sizes. Most "Jägers" would consider 50mm the absolute minimum for anything but a drive hunt rifle, with 56mm strongly preferred. Now, this may not have any direct application to AR/M4 uses, but it does underscore the point that light transmission is definitely the name of the game over here.

    Moving back into a tactical arena, consider that the S&B PM II line (which I think we would all agree is a clear contender for best in class) uses a 34mm tube. There are several reasons for this, most of which can be inferred from K.L.'s post, but when the best tactical (if long range) optics on the planet are using 34mm tubes, it does take some of the shine away from the idea that a 1" tube is still a relevant selection for critical-use situations. Again, we're not really talking AR/M4-specific applications here, but clearly the upper end of the market is moving away from the old 1" standard.

    Chief

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    Which companys are known to use 30mm tubes with the proper inernals? Ive been eyeing an Leupold VXR and they use 30mm tubes.
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    Quote Originally Posted by K.L. Davis View Post
    ...and in a lot of cases, scope manufacturers use the same "guts" in a 30mm tube as they do in the 1" tubes. So, just because a scope has a 30mm tube, it does not mean it has more adjustment, but the only way one knows what the adjustment range of a particular scope is, is to get that spec for that scope.
    I've answered the question from the "Yeah, there's a difference -- one is 1" and the other is 30mm...," and how the latter in no way automatically translates into more ROM, couched it terms of the above, and been told GFY. Veeeeeery frustrating.

    Some folks can see the trees AND the forest. The ones you can't talk to only see only one or the other.

    Big things are made up of little things, and a scope and it's mount(s) are a system in their own right. Add gun/caliber, and it's a fantastic recipe for a fight that looks like something out of Looney Tunes, where all you see is a cloud of dust/smoke with a fist, a star, and exclaimation points floating out of the center.
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    Isn't a scopes ability to "gather light" related to its objective lens more than the tube diameter? Once it hits the first lens, it's being reduced, reversed, resized(magnified) and reversed again. Tube diameter, I'd think, is more related to the size of the internal lenses and their quality/size over light transmission. Just a guess from physics class.
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    Related to, yes. Governed by, no. The devil is in the details, and he's a jealous bastard.

    For instance, nothing in the physical realm "gathers" light, except for a black hole, and I for one am not sticking a gravitational singularity in front of my eye... Yes, a great deal of the misunderstandings revolve around terminology; this is an area where words/semantics matter.

    A larger objective allows more light to transmit, though some will be reflected, some refracted, and some absorbed by the material. The light that DOES transmit has the same thing happen with every single layer it passes through, so any light "lost" is usually to being absorbed by the medium through which it transmits. This is where well-made, well-cut, well-polished glass plays more of a role, to my mind, than the size of the tube, once the light is past the objective. The difference between a 1" and 30mm tube, in this regard, is evident only to instrumentation and afficionados, but arguably may be their center of gravity between choosing between the two.

    EDIT: Also, don't forget, a giant part of the "brightness" factor is from the optic subjectively moving your eye closer to what you're observing. Pretty much anything with magnification is going to "brighten" a scene. I think of the other stuff as refining that most basic premise, but that's open to interpretation and off-topic.....
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    Got it JSantoro, I was just introducing another fold.

    Quality lenses, so I've heard, have more to do with better clarity/brightness.

    Aside from that, I've looked thru some S&B glass, Zeiss, Nightforce and others, but the only time I've seen a difference is in really low quality optics (Nstar, Bushnell, Tasco and such) and that's only because I was switching back and forth at the fun store just to see if there was a difference.

    Besides, if I had a gravitational singularity, I'd start building my Warbird STAT! /nerd alert
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    So you're saying I should get a 34mm S&B??
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    Epic necropost, circa 2007.

    AC

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    Wow.. no kidding! I didn't even notice that.
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    Awww, hell...
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    Quote Originally Posted by crowkiller View Post
    Which companys are known to use 30mm tubes with the proper inernals? Ive been eyeing an Leupold VXR and they use 30mm tubes.
    I too would be interested in knowing this- or how to find out.
    Not just for Leupold-in general.
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    Quote Originally Posted by Zhurdan View Post
    Got it JSantoro, I was just introducing another fold.

    Quality lenses, so I've heard, have more to do with better clarity/brightness.

    Aside from that, I've looked thru some S&B glass, Zeiss, Nightforce and others, but the only time I've seen a difference is in really low quality optics (Nstar, Bushnell, Tasco and such) and that's only because I was switching back and forth at the fun store just to see if there was a difference.


    From what I know on the subject glass is part of it but the coatings have more to do with it, and the coatings are very expensive on pricey optics because there is such a limited market for those products.

    2nd pricey thing is the quality of the internal movements. One of the beefs I have with scopes on the cheaper side is tracking, crispness, and accuracy. A lot of cheaper scopes come 'close' to being true to their designation (1/4 1/2 .10). Obviously to get them spot on the law of diminishing returns comes into play, and it becomes very expensive to get them accurate every time.

    I will say a gun store is not the place to be testing optics. I do think NF makes a really good scope but they are out matched by other brands which do cost more. Ive owned NF, shot other peoples, done tests with other members guns on the range. During daylight theres not too much difference in brightness, and NF is certainly a brand that does put some nice coatings on their glass. What I like about SB personally is during bright days against lighter backgrounds the image appears almost polarized where you don't get tons of glare but during low light they simply come alive. I was shooting with another member at dusk last year, and we each had a NF optic and I had a SB. The SB was simply way ahead when it came to picking out the target which was a black painted steel hanging target against a dark dirt background. The NF optics you could barely make out the outline of the target while my SB was still very bright and had no problem seeing the target.


    And I think it has to do with getting used to the differences, and being able to pick them out. Obviously a quick look through isn't going to show it all.


    The features we are seeing on newer scopes are things some other brands have been doing for a long time in some cases or came out with first. SB has had the Flash Dot system for a decade, and yet still it seems half the industry still can't get a day light visible dot in their scopes.




    And yes this necro thread got a good lot of them.... Still good info though and food for thought.

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    Quote Originally Posted by Jellybean View Post
    I too would be interested in knowing this- or how to find out.
    Not just for Leupold-in general.




    A Short-Dot has -1 to 25MOA of vertical adjustment once zero'd and all that. As far as total adjustment possible Im not sure.

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    Belmont,
    Nice part about my "fun store" is that it's kinda the only transfer point around here, so I spend a lot there. They give me the faux stock with the rubber cups and let me take the scopes outside. Not like I was staring at the far wall of the building or anything. There's still a difference to be noticed even in daylight between the high end stuff and low end stuff.

    I wasn't staring at some stuffed mount in a Cabela's. heheheh
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    Quote Originally Posted by Zhurdan View Post
    Belmont,
    Nice part about my "fun store" is that it's kinda the only transfer point around here, so I spend a lot there. They give me the faux stock with the rubber cups and let me take the scopes outside. Not like I was staring at the far wall of the building or anything. There's still a difference to be noticed even in daylight between the high end stuff and low end stuff.

    I wasn't staring at some stuffed mount in a Cabela's. heheheh



    I know Im just saying actual range time and use is best not casual gun store encounters.

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    Quote Originally Posted by K.L. Davis View Post
    1. A 30mm tubes will/won't pass more light than a 1" tube: This one is silly, but people argue it... of course a 30mm tube will "pass more light."
    I don't think so...


    Quote Originally Posted by Zhurdan View Post
    Isn't a scopes ability to "gather light" related to its objective lens more than the tube diameter? Once it hits the first lens, it's being reduced, reversed, resized(magnified) and reversed again. Tube diameter, I'd think, is more related to the size of the internal lenses and their quality/size over light transmission. Just a guess from physics class.
    I'm not a physicist, but this is my vague understanding... Since the light coming in the front of the scope is reversed upon itself by the convex front (objective) lens, the light really passes all through one point, so the size of the tube is irrelevant, it's all about the front (objective) lens.

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    Follow on question: per Burris advertising, a typical 1" scope tube will house 11mm internal lenses (I believe this is the focus lens and the image erector assembly) while a typical 30mm scope tube will house 15-15.4mm internal lenses:
    http://www.burrisoptics.com/tech.html

    So the internal lenses for a 30mm tube are roughly 36% larger diameter than for the 1" tube.

    Lenses are, obviously, very precisely ground and finished. But there are limits to precision, and assuming that a given manufacturer and price point would use the same machinery to grind lenses whether they are 11mm or 15mm, then if a certain level of precision (WAG: 1/10,000") is possible, the 15mm lens can be expected to be about 36% closer to its intended profile than the 11mm lens, at the same level of precision. That in turn seems like it should improve many aspects of optical quality - resolution, crispness, uniformity from edge to edge, etc. It may also make it easier to prepare aspherical lens shapes rather than spherical ones, since the curve adjustments needed are 36% bigger.

    I am not an expert on this so while I'm making a statement, it's intended as a question for anyone with expertise to answer. I know from experience that cameras and microscopes with larger diameter lenses are almost invariably higher quality optics than ones with smaller diameter lenses, but I don't know the extent to which that is a result of the diameter vs. the extent to which people willing to pay for quality are simply also interested in the larger diameter lenses for whatever reason.

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    Quote Originally Posted by SomeOtherGuy View Post
    ... the 15mm lens can be expected to be about 36% closer to its intended profile than the 11mm lens, at the same level of precision...

    I am not an expert on this so while I'm making a statement, it's intended as a question for anyone with expertise to answer.
    AFAIK, this is pretty much a non-issue.

    People talk about the quality of the "glass" or the "lenses," but for the last couple decades making top quality glass lenses has been easy and cheap.

    What separates the good from the bad from the ugly scopes isn't the quality of the lenses themselves as much as the coatings (anti-reflective and anti-fog) and the assembly of the scope (the alignment of the lenses, for example).

    So, given that it's not so tough or expensive to start with top quality "glass," it doesn't seem like making good lenses of 11mm diameter vs. 15mm diameter would be much of an issue at all.
    Last edited by Bimmer; 03-15-12 at 22:55.

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