Ingwe is correct. The human eye only opens to 7mm exit pupil if your a youngster. As one gets older 5 mm is more realistic.
Ones eyes are part of the optics that are being used and if you don't believe me then close them while looking through a scope and tell me how well you see.
A leupold 6X42 offers as good of light transmission as the human eyeball is capable of.
42÷6= 7 mm exit pupil
Shod
