Choosing Astronomy Binoculars: A Buying Guide
June 30, 2015
Binoculars aren't always down-to-earth! Finding celestial bodies with your binoculars can be just as rewarding as more traditional, terrestrial targets. You don't need an outrageously expensive telescope to peek at the planets - a respectable set of astronomy binoculars and a tripod can be your ticket to the skies.
Astronomy binoculars are some of the biggest binoculars around - but it's more than just hubris. Large sizes allow the maximum amount of light to be taken in, bringing in far-off finds brighter and clearer. And - this might surprise you - astronomy binoculars don't come with the highest magnifications around. Higher magnification creates a smaller exit pupil, meaning you'd actually lose light if your objective lenses weren't large enough to compensate. For astronomical viewing, light gathering ability and optical quality are higher priorities than magnification.
Get a Load of the Sky
A lot of viewers use astronomical binoculars in conjunction with a telescope ... a side arm, if you will. Portable and simple, astronomy binoculars can be used to quickly get your bearings on where to point a telescope. An 8x56 pair is perfect for this use, able to act as a spotting scope for larger instruments or as a viable device for finding impressive sights on their own. True astronomical binoculars, however, see things differently.
To get into astronomical observation without a telescope, a 20x80 pair of astronomy binoculars will really open your eyes. These, or a 25x100 pair, will work even better thanks to incredible light-gathering ability. These binoculars can reveal star clusters, large objects, and great views of the space station if the timing is right. Of course, at this size, you'll need a good tripod, since the weight is more than most people can hold steady.
The Eyes Age
As we age, our irises open less in response to dark environments, making it more difficult to see in the dark. This is a pivotal factor when considering a pair of astronomy binoculars. If your pupils don't get as big as the exit pupil of your binoculars, you'll always take in more light when looking through your binocs. You can and should purchase astronomy binoculars with greater magnification - you'll experience no loss of light. On the other hand, if your pupils are young, you may experience a decrease in light when looking through astronomy binoculars in lower light levels. This is because your pupils can take in more light by themselves, and the binoculars are limiting the light that reaches them.