Zoom binoculars compact binoculars area of use nature wildlife watching travel magnification 7 x lens diameter 21 mm zoom factor 3 times prism system porro suitable for beginner intermediate exit pupil diameter 3 mm angle of view 5 field of view in 1000 m 87 m twilight factor 121 relative brightness 9 focussing system central focus viewing straight binocular material plastic colours silver black included in delivery pouch special feature