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I was browsing through the Leupold catalog and noticed that you can get scopes in 30mm tubes and 1" tubes. Is there an advantage or disadvantage to the diffrent sizes?

I'm getting ready to order a VX-III in 3.5-10x50 to go on top of my new 700VLS in .308. There's like a $100 price diffrence in the two tube sizes. Why?

-Matt
 

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there is also better light transmission through the 30mm tube. same concept as objective lenses. the larger the objective lens, the more light it allows to pass. i've found that with a scope with a 40mm objective lens with a 1" tube vs. a scope with a 50mm objective lens and a 30mm tube the latter will allow you to see your target for up to 45 minutes longer during the hours of dawn and dusk. ie, 45 minutes earlier in the morning and 45 minutes later in the evening.

Brian
 

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We actually talked about this once before. If you do a quick search you'll see what we had to say on the subject.
 

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Max338 said:
a 30 mm tube allows more adjustment for windage and elevation... nothing else..
Better light transmission as well. You can also... if i remember correctly... have a larger exit pupil with a 30mm tube. This will help out alot in low light conditions.

BC
 

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According to Zeiss' sales representative in Norway, and this woman knows optics, there's no noticeable difference in light transmission in 30mm tubes vs 1". As the light passing through the tube is a aprox 3-4mm in diameter it wouldn't really matter whether you have 1", 26mm, 30mm or 34mm...

And according to Swarovski, they could make a scope with a 19mm tube with the same light transmission as on their 30mm scopes. A friend of mine has been at some course at the Swarovski plant in Tirol, three times, I believe - and each time the question about light transmission in 1" vs 30mm has been asked, and each time the answer has been "no difference".

The largest exit pupil your eye can deal with is aprox 8mm, and seeing as the ocular is bigger than the tube...well...
 

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My understanding is that it is not light transmission, but light gathering. There is a difference. Transmission allows the gathered light to be transmitted, the less the amount of loss, the better. But, if you have more light gathered to transfer, then that is better also. The size of the objective combined with the size of the tube work together to increase the amount of light to be transmitted throught he lenses. The light transmission is a result of the quality of the lenses themselves and the coating on those lenses.

MEL
 

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There's no difference in light transmission between the different tube sizes...honestly.

The difference is purly mechanical. More adjustment in elevation and windage, and a wider range of zoom - 4 times vs 3 times on the 1" tube.
 

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Yes, I do not disagree, but I'm not talking about light transmission, I'm talking about light gathering. Though I'm certainly not an optics expert, so I may be wrong here.

MEL
 

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Mmm..but as far as I understand, the object handles the gathering. Then focus it into a bright cone which hits the tube lenses, which - I think - focus it into a beam and then transmits it through the rest of the lenses as a beam. Until it hits the lenses in the ocular.

Oh well...I think the bottom line is that two scopes with the same optical quality, one 30mm and one 1", with the same object sizes, will have such a tiny difference - if any - that you will not notice with your 20/20 eyes.
 

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I think the two best reasons for a 30mm tube are more elevation and stronger, stiffer tube.

(Structurally seaking, tubes get stronger as they get wider)
 
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