30mm vs. 1" tube scopes

[Grampa]

I'm looking for a lower power variable scope, and am leaning towards either the European (30mm) or standard (1 inch) 1.5x4 Leupold. Both have the same size ocular.

What advantages might he 30mm tube have?

I would think the larger tube would gather more light, however, that might be offset by the lenses actually having to be thicker in the center. Any difference in field of view? In cameras, the smaller iris has a better depth of focus, but I doubt that would be significant in a rifle scope.

I presume that neither is going to be superior as far as strength and quality.

The rings I want to use are the same price for either size.

Thanks!

 

[Jim Watson]

The main advantage I see is that the larger tube has more room for the erector tube to move and a wider range of adjustment for long ranges. Which doesn't matter much in a low powered scope on a hunting or CQB rifle. I think a 1" 1.5-4X would do fine.

 

[Grampa]

Good point.

I hadn't considered that the mechanicals would have to be bigger. Not only would there be a greater range of adjustment, but that means more weight to those parts. More inertia on those parts during recoil.

Hmmm...

 

[Zak Smith]

I would think the larger tube would gather more light, however, that might be offset by the lenses actually having to be thicker in the center. Any difference in field of view?

Main tube diameter does not affect "light gathering" nor brightness of the image.

Jim is correct that it primarily affects erector travel. A larger diameter tube is also stronger, but this is generally not a problem in rifle scopes.

 

[oregonshooter]

If you are not shooting past 600 yards then it usually does not matter. I use 30mm for the travel increase on my gun. Shooting under 600 is just too easy.

Nice articles in the sigline Zak!

 

[cheaptrick]

You could always go with a 1" tube and a 20 MOA rail to make up for the lack of "up".
30mm scopes are "typically" more expensive.

 

[45crittergitter]

Scopes with 30mm tubes can contain half again as many windage and elevation clicks as scopes with 1” bodies, according to Leupold. Also, a 30mm tube can (but most American scopes don’t) accommodate larger erector lenses, for a brighter, clearer, image. When the adjustments are set away from center (in any scope), the optical system is essentially bent, with the erector tube tilted inside the scope. This often results in serious parallax problems, and at the extremes of the adjustment range, each click moves the erector tube less consistently.