Beginner’s Guide To Binoculars

by VirtualAstro on November 25, 2011

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Credit: opticsreviewer.com


Before you consider buying expensive equipment for viewing the wonders of the night sky, binoculars are one piece of equipment every amateur astronomer should have.

Many beginners to astronomy (especially around the holiday period) are sometimes dead-set on getting a telescope, but many aren’t aware that a good pair of binoculars can outperform many entry level telescopes for a similar cost, or much less.

Binoculars are simplicity in themselves — maintenance free, instantly available for use and very versatile, as they can be used for daytime, or “terrestrial viewing” just as well. It is difficult to say the same for with most telescopes.

Go into any photographic store, or website that sells binoculars and you will be met with literally hundreds of different makes, types and sizes – confusing for the beginner, but with a few pointers it can be easy to choose.

Credit: astronomybinoculars.com

So how do you choose a pair of binoculars that will give good results with astronomy?

When choosing binoculars for astronomy, the only variables you need to think about are size of the optics and weight.

Too small and they won’t be powerful enough or let enough light in; too big and heavy means they are almost impossible to use without a support or tripod. Beginners need to find a pair of binoculars which are just right.

The key is to get as much light into the binoculars as possible without making them too heavy. This will give sharp views and comfort when used.

Size and weight come hand in hand, the more light gathered, the heavier the binoculars will be.

All binoculars are measured or rated by two numbers, for example: 10 X 25 or 15 X 70. The first number is the magnification and the second number is the “objective diameter” which is the diameter of the objective lens and this determines how much light can be gathered to form an image.

Credit: Halfblue Wikipedia


The second number or objective diameter is the most important one to consider when buying binoculars for astronomy, as you need to gather as much light as possible.

As a rule of thumb, binoculars with an objective diameter of 50mm or more are more suited to astronomy than smaller “terrestrial” binoculars. In many cases a larger objective also gives better eye relief (larger exit pupil) making the binoculars much more comfortable to use.

For the beginner or general user, don’t go too big with the objective diameter as you are also making the binoculars physically larger and heavier. Large binoculars are fantastic, but — again — almost impossible to keep steady without a support or tripod.

Celestron Skymaster 15 X 70 Binoculars

Good sizes of binoculars for astronomy start at around or just under 10 X 50 and can go up to 20 X 80, but any larger and they will need to be supported when using them. Some very good supported binoculars have objective diameters of more than 100mm. Theses are fantastic, but not as portable as their smaller counterparts.

Binoculars are one of the most important items a new or seasoned astronomer can buy. They are inexpensive, easy to choose, use and will last a very long time.

Enjoy your new binoculars!

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Ethan Siegel November 25, 2011 at 11:48 PM

Adrian, that’s WAY too much magnification!

I’ve never known anyone for whom 15, 12, or even 10x magnification was anything more than utter frustration without a tripod! (The jitter is simply huge!) I always recommend 7×50 for beginners without a tripod, as you still get sufficient magnification to see interesting features at the Moon’s terminator, to split wide binary stars and to get interesting (non-point-like) views of Jupiter, Saturn, Mars and Venus.

But if you give someone a 15×70 or 20×80 pair, I don’t know how they’ll be able to get any good views with that as a “first pair” of binoculars.

Just my 2 cents.

Virtual Astronomer November 26, 2011 at 3:12 AM

Not at all, I have always recomended and use those magnifications. It all depends on the individual for stabilization

Bill McLaughlin November 26, 2011 at 12:17 AM

If you want to use them for astro, and can afford the somewhat higher price, stabilized is the way to go. Avoiding the jiggle keeps the photons going to one spot on the retina instead of being smeared about, making them equivalent to a larger pair of non- stabilized for which you would need a tripod to match. I use a pair of Canon stabilized, which are great.

Marc Wittmann November 26, 2011 at 2:32 AM

question:
does exist binoculars with 1)digital photography and memory storage -cards?- and 2) easy infrared photo abilities? I know the Deep Sky Imager II & III ccd’s of Meade for infrared views, but they are quite expansive. Could you have a good idea or tiips?

Virtual Astronomer November 26, 2011 at 3:15 AM

10 X 50 is an ideal size and very stable

Anonymous November 28, 2011 at 1:28 PM

A pair of binoculars is “very stable” by itself if it’s sitting on the ground. If someone is holding them then stability depends on the person.

You should understand that different people have different hands. Not everyone can use 7x50s comfortably, and it only gets worse if the binoculars have to be used with glasses due to astigmatism or similar.

Guy Stalnaker November 26, 2011 at 6:23 AM

Hmmm — as I already have a pair of binocs I can use, and have tried to use, I can say that I suffer from what Bill below calls ‘jiggles’ even though they’re 10×50 (just not very stable for my holding of them). Rather than spend $ for another set, what’s the best way to use them? Mounting seems like a good idea, but how does one do that? They’re Bushnell and quite fine. I’ve seen Jupiter’s moons and the Andromeda galaxy with them however jiggley.

Anonymous November 27, 2011 at 1:59 AM

Please, when writing for “beginners”, avoid jargon, and certainly, don’t explain jargon with more of the same! ie:”better eye relief (larger exit pupil)”

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