You can significantly extend your astronomical reach with binoculars. Consider that under a good sky without optical aid, you can see close to 3,000 stars. Ordinary binoculars increase that count to 150,000!
Chances are, you already own binoculars, so give them a try. You might be pleasantly surprised by what you can see. Start with the Moon—it’s amazing in binoculars. You can see the largest craters and identify dozens of individual features. And that’s not all. Once you know your way around the constellations, binoculars will allow you to sweep up interesting star clusters, nebulas and even distant galaxies. Binoculars excel at showing large areas of sky—something telescopes don’t do very well. That’s why experienced amateur astronomers usually keep binoculars close by.
Enter the Binocular Universe
What kinds of binoculars are best for stargazing? There are many options, but two specifications are the most important: the magnifying power and the size of the front lenses. Luckily, these two crucial pieces of information are normally printed right on the binoculars.
Typically, you’ll see something like 7×35, 8×40 or 10×50. The first number is the magnification, and the second gives the diameter of the front lenses in millimetres. For example, 7×35 binoculars magnify seven times (7×) and have a pair of front lenses that are each 35 millimetres across. Similarly, 10×50s magnify 10 times (10×) and have 50-millimetre front lenses.
So which power/aperture combination works best for astronomy? As with so many things, there are inevitable trade-offs, but most amateur astronomers find that 7×50s, 8×56s or 10×50s are excellent choices. I personally prefer the detail that the extra magnification of the 10×50 size provides, though some opt for the wider fields of view that 7×50s offer. As I said, there are trade-offs. If possible, try before you buy.
To use binoculars effectively for astronomy, you must be able to hold them steadily something that gets tougher when the binoculars magnify more than 7× or when they’re heavy—which is why many binocular astronomers use a tripod or specialized mount. Others prefer the convenience of image-stabilized binoculars, which have an internal opto-electrical mechanism that counteracts the jiggles introduced by hand holding them. Engaging the stabilization produces an almost magical steadying effect that works wonders for stargazing. My favourites are the image-stabilized binoculars made by Canon.