Hi
@Philip Glass I bought several of the Leupold 1.5x5x30mm illuminated and 1.5x5x24mm non-illuminated scopes. Ironically, they are the same scopes, the 30mm provides ZERO additional glass or light gathering, its just the 24mm glass in a 30mm tube making room for electronics. The light gathering on these scopes is abysmal @ a $400-$500 pricepoint.
Its important to remember, that going from a 1" to 30mm tube, does not, and is not intended to, increase light transmission. Light transmission is directly related to objective size, lens coatings, and glass quality and number of lenses. Tube diameter has no effect.
A 30mm tube allows for more adjustment range and sometimes makes for a stronger tube due to increased wall thickness, not always though. 30mm scopes are not needed for illuminated reticles, but many do utilize a side illumination control with a 30mm tube.
Being that light transmission is tied directly to objective size and lens (coating, quality, and quantity), if you're looking for a higher LT, better to go with a larger objective than 24mm to start. This brings into question of exit pupil and usable light as well. Depending on your age and how your pupils dilate, many scopes in this range give ample usable light, some are more finicky. If you have a high mag scope with small objective, you will have a much narrower EP and require a very precise cheek weld and still not achieve the brightness you desire depending on conditions.
We can also get into how some companies achieve these higher percentages. I've been fortunate enough to be around when many were cut open, even the highest dollar models, to see what they are working with. I've seen numerous companies remove lenses from previous years models to achieve more LT or swap various grades of glass to get different weights or LT. The optics world is truly amazing.
You cant go wrong with a Leupold, a Swaro, a Trijicon, etc, but there may be one that meets your specific needs. Mine was a leupold vx3 2-8x36. Had the ER, LT, EP, Mag, weight, and durability I needed and at an employee price was a no brainer personally. I would certainly swap it for a VX6 as mentioned by
@Philip Glass pr
@CAustin in a heartbeat as well.