Book 31, Question 127
What do the numbers on binoculars mean?
The first number tells how many times bigger the view looks.
Binoculars often have two numbers, like 8×42. With 8×, a bird looks eight times closer. The second number is the width of the front lenses in millimeters. Larger lenses let in more light, which helps in dim woods. Higher magnification can make the view shakier, so many birders pick 8× or 10×.