Marine binoculars area of use nature watersports magnification 7 x lens diameter 50 mm prism system porro exit pupil diameter 68 mm angle of view 75 field of view in 1000 m 132 m twilight factor 194 focussing system individual focus viewing straight binocular weight 890 g additional functions compass backlight special features rubber armouring outdoor function waterproof prismenglas bak 4