Binoculars & Telescopes

What is the difference between binoculars and telescopes?

Binoculars are simply two small telescopes joined in such a way as to comfortably fit eyes of various separations and eyes that require different focusing settings.

How they improve viewing the sky?

They both enlarge objects seen through the lenses and they also gather or increase the light that reaches the eyes.


In this article I won’t attempt to explain how lenses in binoculars improve viewing but as astronomers we need to know these fundamentals.

  • Night viewing requires lots of light from objects reaching the eyes and as much magnification as different objects require.
  • The more light we collect the larger and heavier the lenses required.
  • The more magnification we attempt the smaller the field of view or amount we see.

So binoculars are limited by size and field of view (or how much we see in the eyepiece). These problems are to a large degree overcome in telescopes, seen in part  11.

The ideal binocular viewer

A good compromise for all night viewing is the 7 X 50 pair of binoculars.

  • 7 refers to the magnification or enlargement,
  • 50 refers to the diameter of the outer light gathering lenses in millimetres.

Personally, for my eyes and general use at my age  I find 8 X 32 very adequate and very convenient for finding bright star groups, comets and many double stars. For greater power and light I go for supported 25 X 100 binoculars or a small telescope.

Other Uses: A real advantage of binoculars over a telescope is the variety of daytime uses it can be put to should you find your passion for astronomy disappear.

Amateur astronomers from Shoalhaven Australia.