Re: 30mm vs One Inch tubes
It is a common myth that a 30mm tube allows for the transmission of more light. All else being equal, the single most important factor in light transmission is the size of the objective lens (aperture). The quality of lenses and coatings are, of course, of paramount importance. The objective lens concentrates light into a small bundle. It doesn't matter if this small bundle travels through a 30mm tube or 1 inch tube as long as no part of the scope (lenses notwithstanding) encroaches into any part of it. The best example I can think of to illustrate this is your basic astronomical telescope. These may have a 200 inch aperture (objective lens or mirror), yet the light is concentrated and comes out of a tiny little eyepiece in a bundle only 4 or 5 millimeters in diameter.