Oldtrader3
Ammo Smith
- Nov 6, 2009
- 8,406
- 5
Divide the effective mm diameter of the objective lens (see manufacturer spec sheet for this number) by 6 which equals the magnification to give you a 6mm exit pupil. If you check scopes which are set at whatever magnification yields a 6mm exit pupil in each, you are comparing apples to apples for scope brightness because your eye sees the same size pupil in each scope.