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We have no argument about the "main" reason for a larger tube. I chose my words carefully.
What I said, is that "all else being equal" the larger tube WILL allow for more light transmission, and that is a fact.
I disagree.
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Crazy Ol' Foole
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Hmm . . . Swarovski optics or some guy on a crossbow forum. See post #2.

https://www.swarovskioptik.com/hunting/blog/RS_tube_size_matters_but_not_much

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And right in his article title it says that it matters.
Listen, I get it that EP makes more difference than tube size, but his explanation is a bit incomplete for the sake of brevity. Understanding the arrangement of lenses inside the scope, the difference in coatings, whether it is a fixed or variable power, as well as how durably it's built are all things to take into consideration, but when you boil it down to "all else being equal" tube size DOES matter.
 

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but when you boil it down to "all else being equal" tube size DOES matter.
Nope. The only advantage of a 30mm tube versus 1” is additional strength and more adjustability for the turrets. Some people think a 30mm tube increases the FOV and that’s not always true either.
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For additional info, I would direct you folks to a site by Ilya Koshkin called Optics Thoughts.
I enjoy Koshkin’s post - which one in particular are you referrer got?
 

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For additional info, I would direct you folks to a site by Ilya Koshkin called Optics Thoughts.
Found it.

http://www.opticstalk.com/30mm-vs-1inch-tube-for-light_topic1696.html

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All right, this has been addresses many times, and there are many opinions. Most of the comparisons between 30mm and 1 inch scopes are not apples to apples because of different coatings, polish, etc.

If we are talking about the difference between 30mm and 1 inch tube scopes and assume that optical quality is identical there is no difference whatsoever in light transmission. I may not have as much experience with different high end scopes as many other people here, but I do have a pretty decent idea of how an optical system works due to my background: I have a degree in applied physics specializing in optics from Caltech and I work with optoelectronic devices for Raytheon (lately, next generation night vision weaponsights and goggles).

I've seen a lot of passionate arguments on this here and on other forums. People keep on referring to this as an opinion, but it really isn't. It is a cold, hard scientific fact: with the same objective size, same optical quality and same number of lens surfaces, in absense of vignetting (non-issue for rifle scopes), 30mm and 1 inch maintube scopes will have identical light transmission.

I apologize if I ruffled anyone's feathers with this, but this issue needs to be put to rest.

Ilya

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I’ll go with the Optics Master . . .

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Crazy Ol' Foole
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I’ll go with the Optics Master . . .

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I read his stuff too. And I'll concede the difference between 1" & 30mm, but not the larger tubes (1" vs 34-35mm).

Really, the difference between fixed vs variable power scopes and the number of lenses involved is a much bigger deal. Ilya has written about that as well.
 

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Crazy Ol' Foole
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For what reason?
An over simplified answer is;
That it's typically an issue that is a combination of eye relief (focal length)and magnification. The closer to max magnification you get, the more critical proper eye relief becomes. Improper eye relief tends to cause "tunneling"....a type of vignetting. A high magnification scope that is also shorter OAL will often tend to be more susceptible to this problem, which is part of the reason why there are so few high power short length scopes that are acceptable w/o spending a small fortune.
 

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An over simplified answer is;
That it's typically an issue that is a combination of eye relief (focal length)and magnification. The closer to max magnification you get, the more critical proper eye relief becomes. Improper eye relief tends to cause "tunneling"....a type of vignetting. A high magnification scope that is also shorter OAL will often tend to be more susceptible to this problem, which is part of the reason why there are so few high power short length scopes that are acceptable w/o spending a small fortune.
I am enlightened. Thankyou
 

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best low light scope i own is 3x9-42 kahles cl multi-zero coatings on glass and coating on crosshairs make this the best low light i have. Actually sold the best being stupid Kahles 3x12-56.
 
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