explain objective size to me again

[hofts]

i am considering a nightforce nxs 2.5-10x24 scope for a 270 wsm.

i have never had an objective that small, and think it will not let in enough light for very early morn and late evening hunts. this scope does have an illuminated reticle. will this let in as much light as my vx3 4.5-14x40? does a 4.5-14 x50 let in a lot more light than the other?

please advise

thank you.

[Jack]

Objective size is expressed in millimeters, and is a measurement across the front lens of a scope.
Generally, an optic such as a scope or binocular, will transmit as much light thru it as your eye can accept if the objective lens diameter is 7 times the magnification (power) of the optic.
Going by that formula, a 2.5-10x24 optic would acheive maximum light transmission at the 2.5 end of the magnification range. But only at minimum power.
A 2.5-10 scope with a 40MM objective would acheive maximum light transmission up to about 5-6 power.
Now, on the flip side, the larger objective scopes, like a 50MM objective, have no advantage whatsoever during 95% of your hunting day. Only during those last few minutres of legal shooting time does the larger objective help you.
Frankly, it's been my experience that if you hunt where the regulations allow hunting from dawn to dusk, the huge objectives (50MM +) help very little, if at all- and only at quite high powers.
Illuminated reticles have nothing to do with light gathering. They will help you see the reticle clearly when it's really dark, like for poaching game at 2 AM
Just kidding...an illuminated reticle will help you see the reticle, but it will do nothing to help you find the target in the scope- it actually may hurt a little. The light from the illuminated reticle may fool your eye into thinking there is more light outside than there really is, causing your eye pupil to close down slightly- making everything but the reticle appear darker.

[Dom]

I'll add that for most 'daylight' areas, yes, a 40 or 42mm objective is quite adequate; however, you will also have a larger field of view with a 50mm objective, as well as brighter picture as light fades. As Jack notes, the illuminated reticle has nothing to do with it's light gathering ability. I'll add though that I love 'em cause I hunt in low, make that very low light, and if you can't adjust the brightness down to almost nothing than you don't want one.

That 24mm is really small for an objective on a variable scope that goes to 10x -- maybe it's intended more for bench and not hunting? I'd recommend you visit a reputable optics store, look thru a few, to get a feel for what you can see. Granted, it's not like taking them out hunting, but I'd be leery of a 24mm for hunting, Waidmannsheil, Dom.

P.S. I also have a Vari X III 3.5-14 x 40 IR, or is it 4.5-14x40, can't remember, but you might want to put that on your WSM? That's a real decent scope. Kinda depends on how it looks on the rifle intended for and your personal tastes.