Understanding optics...

What the numbers mean?

What do the numbers on my scope mean?

Binoculars and telescopes are usually marked with a set of two numbers separated by a 'x'; 8 x 20, 8 x 30, 8 x 40, 10 x 50, 30 x 80, and so on.

The first figure indicates the degree of lens magnification and the second, the diameter of the objective lenses, in millimeters.

See also:

- What do the numbers on my scope mean?

- What is magnification?

- What is the field of view

- What is an objective lens?

- What is eye relief?

- What is the exit pupil?

- Twilight Factor

- Relative Brightness