Test Your Birding Optics Knowledge

Optics Question #1

Optics Question #1

When you see a binocular described as a 10×42 or an 8×30, the first number refers to the power or magnification. What does the second number refer to?
a) The weight of the binocular
b) The close-focus of the binocular.
c) The size of the front (objective) lens
d) The number of rotations of the focus wheel from close focus to infinity.

answer

Subscribe & Save!

ONE YEAR (6 ISSUES) of Bird Watcher's Digest magazine
GET FREE AND INSTANT ACCESS to our digital edition
SAVE 33% off newsstand prices
PAY ONE LOW PRICE of $19.99!
Scroll Up