There are two types of 30mm tubed scopes.

Those that have larger lenses than 1" tubes and therefore allow more light to pass through them and those that have equal sized lenses but allow a greater range of adjustment.

Typically tactical 30mm scopes will have 1" glass internally to allow for a greater range of adjustment for windage and elevation corrections. This is how Leupold scopes are manufactured.

Typically European (Swarovski, Meopta, Zeiss) hunting scopes will have larger internal lenses to allow more light to be transmitted through the scope.

The size of the exit pupil (determined by dividing the objective lens by magnification) simply corresponds to the diameter of the ring of light when it reaches your eye. It is true that your eye will only dilate to a certain diameter. If the exit pupil of the scope is larger than your eyes pupil then the light outside your pupil is wasted light. However if the internal lenses through out the scope are larger they will allow the exit pupil to be brighter.


A very simplistic way to look at this is to take two equal rooms that are the same in every way except the size of the window in each. One room has a 1'X1' window and the other room has a 2'X2' window. Which window will transmit more light into the room?

The other benefit to a 30mm tube is that they are stronger than a 1' tube of equal length.

Leupold isn't going to tell you the advantages of why you should buy some other companies scope because as BC explained Leupold does not use 30mm glass in any of their scopes. They are simply giving you the advantages of Leupold 30mm scopes compared to Leupold 1" scopes and not Swarovski 30mm scopes. However, they do tell you that light transmission "is a function of optical design and not tube diameter". Optical design includes lens diameter.

I am eye'in up a Mark4 tactical 4.5-14 myself.

any opinions on the Mark 4 4.5 x14? I am also looking at putting one on my new 270wsm. I would rather get the 1" tube, but can get the mark 4 for a lot cheaper thru special programs for military.

I dont know if the extended turrents will cause problems with carrying and packing.

I don't currently have one, but have fondled a few. Its close to as good as it gets. I am sure others will tout the kraut glass. But I will be thrilled to get one.