re: 3 scope choices...opinions wanted please

I am a vortex guy - 4x16x50 is as big as I would go unless you are planning long shots (500+ yards that require high magnification). I shoot the Diamondback HP 3x12x42, and it is a better low light scope than any of the 50mm objectives, in fact I am switching most of them over to the Diamondback series (1" tube).

A little about objectives and better low light visibility - Exit Pupil (diameter of available light at the optic nerve) is calculated by dividing the objective lens diameter by the power of magnification. So a 3-9x40mm scope has an exit pupil of 13.333 at 3x, 6.667 at 6x and 4.444 at 9x; while the 3-9x50 scope has an exit pupil of 16.667 at 3x, 8.333 at 6x and 5.556 at 9x. Even if you have great eyesight your eyes can not use all of the light provide by either scope at 3x. The reality is that this difference is so small that it's almost insignificant.

Exception / Big Exception......at 9x the 50mm scope has a 25% larger exit pupil than the 40mm scope. This is significant! since our eyes allow in an approximate circle of light. A 50mm scope provides 56% more available and useable (by our eyes) light than the 40mm scope at 9x! However, this is only useful if you hunt at 9x power. If you hunt at any magnification less your not getting the benefit of this 56% greater light. But if you hunt at dusk at 9x, then 56% additional light is a big benefit!