The reason why quality glass and coatings are used in quality optics is to allow that optic to transmit as much light coming from the subject as possible w/o distorting and scattering that light. If the light passing through an optic is scattered or distorted, it bounces around inside that optic and degrades the image quality.
While their are tests using fine optical test equipment that do test for differences in image clarity, the standard that is used by rifle scopes is a simple test to see how much light passes through that rifle scope. Both daylight and twilight light is usually tested.
In tests like this, Leupolds have, for many years now, tested right with the best out there. But those who do their own comparisions sometimes see significant differences. So the question comes down to why.
As far as I am concerned, if you want to claim that a Zeiss or an S&B is a better rifle scope because you can see say .25 caliber bullet holes at 100 yds. where all I can see are .30 caliber and perhaps a few 7mm bullet holes, that's your call. I say the Leupold is better simply because of their first class rep for holding zero and their huge eye boxes. Both of which are far more practical aspects of rifle scope performance than some tiny bit of resolution ability. E
