Some Advice on Picking an Astronomical Binocular

Copyright © 1998, 2000, 2002, 2004, 2006 Jay Reynolds Freeman (

The most important advice is to seek out a local astronomy club -- perhaps from the annual directory in Sky & Telescope or Astronomy, or via their web sites, and Go to their star parties to try out other folks' telescopes, binoculars, and so on. Sometimes people will be so eager to show you things, that you can put off buying your own equipment for years and years.

The frequently-asked questions list (FAQ) for telescope purchasing, that appears on usenet newsgroup, "sci.astro.amateur", has information about binoculars. It includes a section on how to hold them steady. Wade through it and look for what you need.

Any binocular you find lying around will provide better views than the naked eye. Possibly you should not buy one at all, just mooch from friends or family for a while, till you know what you are doing.

Binoculars are low-power instruments that show little planetary detail. The moon will look wonderful, and you will be able to see moons of Jupiter and phases of Venus, but probably no other planetary stuff. Yet many deep-sky objects lie within range of a small binocular -- I have seen all the Messier objects with a 7x50 (some were very difficult), and lots more. The Great Spiral Galaxy in Andromeda, the Orion Nebula, and the summer Milky Way, will be wonderful.

The "right" binocular for most people is about a 7x50 (that is, it magnifies seven times and has front lenses 50 millimeters in diameter). Big front lenses gather more light and show fainter objects, but with lenses much larger, or magnifications much greater, the whole instrument may get too big and heavy to hold steady. Some people like more magnification -- 10x50s are common. I have a 14x70 I like, but it weighs twice as much as a 7x50; not everyone can keep it steady. If you are older than forty or fifty, the pupils of your eyes may be too small to take in the big beams of light emerging from a 7x50 binocular; a 10x50 might be best.

You can pay $1000 for a 7x50 binocular, but cheap and sleazy imports sell new for as little as $50, and sometimes real bargains show up at garage sales and such. If you are on a budget, do not worry if you must buy the cheapest and sleaziest binocular you can find -- it will be lots better than the naked eye -- but expect friends and fellow net-posters to be critical and condescending. Ignore us: We believe that fancy gadgets make us morally superior, we are dumb enough to think that more money always makes things better, and we are too cowardly ever to admit wasting money on something that wasn't worth the high price.

On the other hand, if you like high-tech gadgets, or if you are willing to pay a lot for the best binocular possible, and if you are certain you know exactly what you want, then go ahead and buy a more expensive one -- it will give noticeably better performance -- but expect friends and fellow net-posters to be critical and condescending. Ignore us: We believe that inexpensive technology makes us morally superior, we are dumb enough to think that more money never makes things better, and we are too cowardly ever to admit that our needs and desires have outstripped our budgets.

Seriously, a lot of what you pay for in a costly binocular is mechanical robustness and resistance to hostile environments. Biologists' binoculars get trampled by rhinos; geologists' fall into volcanos. Nautical units are exposed to yucky salt air, engine vibration, and attack by marauding submarines. Astronomical binoculars lead more sheltered lives, so there is no need to spend extra money and put up with the extra weight of a binocular built for harsh conditions.

Take care of your binocular. Things that will hurt it include heat (don't leave it in the sun, even in the case, especially inside a car), moisture, dust and dirt (do use the lens caps and case), vibration (don't toss it on the bed of your pickup for the drive up the mountain), and raccoons. Only the latter take protection payments.

When you are about to buy a binocular, try a few simple tests:

Have fun, keep your dark adaptation, and remember -- raccoons like Oreos.


As I write these words, I haven't had usenet access for a while, so I am not sure whether the instructions on how to hold a binocular steadily, that I mentioned above, are still there. I wrote the original of that part of the usenet FAQ (though I did not invent the technique and I have no idea whom to credit for it), so I thought I would append it here, with a few updates and clarifications.

If you don't use a tripod (and tripods are sometimes clumsy, and can be difficult to use when the binocular is pointing nearly straight up), it is important to know how to hold a binocular so it stays steady.

The way most people grab a binocular is with one hand on each side of the middle of the body, roughly where the prisms are in a conventional unit. Thus the left hand is just left of the center of gravity of the instrument, and the right hand is directly opposite. That is a comfortable position, because the binocular is balanced in the hands of the user.

For most people, there's a better way. Hold the binocular to your eyes, with your hands positioned as just described. Now, slide your hands back along the body of the instrument, toward your face, until only your pinky and ring fingers are curled around the back end of the binocular body, clamping it against the heels of your hands. In this position, the binocular feels a little nose-heavy, because you are supporting it behind its center of gravity, but we will deal with that in a moment.

Now curl each thumb up as if you were making a fist, and flex your hands so that the second bones in from the tips of your thumbs are pressed against your cheekbones (count the bone where the thumbnail is as the first bone). This makes a solid structural connection between the body of the binocular, through your hands and thumbs, to your face, and markedly improves how steadily you can hold it. Similarly, curl the first and middle fingers of each hand around the corresponding binocular eyepiece, for a little more structural contact, and also for some protection from stray light. In this position, your hands are not far from where they would be if you were peering through a store window at night, with your nose pressed right up against the glass, and brought your hands to your face to block out stray reflections and glare.

In this position, the binocular is out of balance -- it is nose-heavy. Yet for most people, the added stability gained by rigid contact between the bones of their hands and cheeks provides markedly steadier viewing, so it is worth a little bit of out-of-balance.

If the binocular is too long and heavy, however, (say, a 10x70 or an 11x80), the out-of-balance position can get tiring. In that case, move one hand out to the objective end of its side of the binocular, so you are supporting the instrument on opposite sides of its center of gravity -- it is in balance, but with a structural connection between it and your face through only one hand, the other one. When the hand way out there gets tired, switch hands.

For each person, there is a limit to how heavy and powerful a binocular can be, before there is no way to hold it steady enough. I am an averaged-sized adult male in reasonable physical condition, and I find I can hold a 14x70 (Orion's) steadily enough to use indefinitely on astronomical objects. Anything much bigger is a real pain to use for more than a few minutes. When I was younger and smaller, I might not have been able to deal with the 14x70 as well as I do as an adult. Your own experience may vary with your strength, size and condition. Try before you buy, if at all possible.