Why do AR optics have 24 mm objectives

[scott_r]

Why do the vast majority of AR style optics have a small 24mm objective? Would it not be better to have a larger objective lens? Why not a 1-4x40 or 1-7x40? Most AR's, Tavors, XCR's have plenty of room for a larger objective.

Cheers!!

 

[canucklehead]

Because it's all about exit pupil.

A 1-4x24 optic has minimum 6mm exit pupil. The human eye can't use much more than that - hence, a bigger objective (for a low mag optic) is basically wasted. More weight and cost for limited/zero benefit.

 

[Trinimon]

Thanks Canucklehead...

 

[supernova]

As stated, its not needed. FOV, exit pupil etc gains are minimal and not worth the extra bulk and weight. With modern glass we are even seeing mid level magnification with 24mm objective lenses. The image is still bright, clear and has a wide FOV.

 

[scott_r]

what about scopes in the powers above 4? Like a 1-6 or 1-7?

 

[Onagoth]

I would expect it has to do with weight.

 

[rodregier]

With a flat-top upper you can run just about any optic you want.

Some choices will be better matched to the size of the rifle than others.

 

[rodregier]

ht tp://riflescopecenter.net/top-5-best-ar-15-scopes/