About Astronomy

Amateur Astronomy and Telescopes

Beginning Steps

Binoculars: Before You Get A Telescope!

It is reccomended to get a pair of astronomy binoculars before you get a telescope.  Why?  Because binoculars give you low power, wide field of views of the sky which enable you learn the sky better. 

Don't get binoculars with straight barrels (Binoculars with Roof Prisms), get the ones with barrels that are smaller in the back and wider in the front (Binoculars with Porro Prisms).  The reason why is because Binoculars with Porro Prisms allow for more light to pass through.  Also, for better light transmission and highly reduced glare, try to get multi-coated to even fully multi-coated binoculars. 

A good size of binoculars for beginners would be 7x50s, or maybe a little bit bigger.  They're powerful enough to give you great views of Deep Space Objects, yet light enough to use without a tripod.  When someone says their binoculars are "7x50's", that means that the magnification is 7, and their barrel aperture at the front is 50mm.  Another important characteristic of binoculars to know are the eyepiece's exit pupils, or the width of the part of the eyepiece in which the light enters your eye.Now, about exit pupils:  To find the size of the exit pupil of the binocular's eyepieces, divide the barrel diameter by the magnification.  The average person above 40 years old has pupils which dilate to about 4.5 millimeters.  Below 40, about 5-5.5 millimeters.  Some teenagers and kids' pupils can dilate to even 6 millimeters!  Why is this significant?  It's important to have binoculars that have exit pupils which match the size of your pupils.  Now you don't have to get binoculars the exact size of your pupils,  you're just recommended to do that.  It makes observing much easier on the eyes. 

Once you feel you know the sky, get a telescope.  For info on telescopes, go to the "Telescopes" link.

Picture from BigBinoculars.com, Oberwerk 15x70's