Does a 50mm telescopic gunsight with a 30mm tube transmit more light than one with a 1 inch tube?

Question

For those that dont know specifically about gunsights, there is a varietry of lense sizes from 20 to 80mm. each is available with a 1 inch or a 30mm tube between them forming the structure of the sight. The 30mm versions are more expensive.
Because this tube becomes part of the reciever structure, I can see that bigger is better, also more room for evevation setting, but is it brighter.
On an air rifle or a well made 22rimfire, for example, the rigidity and adjustment are not relevant. Would I be wasting my mony buying a 30 mm version.
I have herd all sorts of opinions in the past. I would love an answer from someone who could put some solid theory to this question.

Answer 1

Hi. A 50mm objective is at one end of a conical light path. The focal length determines the cone angle and as long as the cone is not intercepted either should work. The tube could even be conical I suppose. But a cylinder allows for better baffling.