Binoculars For Astronomy

Top 5 Reasons To Own Binoculars For Astronomy:

#5. Try hanging a telescope around your neck! 
Time Exposure of M45, A Great Object in Binoculars
 (author: Filip Lolić)
(image source)
#4. They work on squirrels and birds, too.
#3. They are cheaper than an observatory.
#2. Two eyes are better than one.
#1. You will use them more than anything else.

A good pair of binoculars can be an inexpensive and convenient way to enjoy astronomy. Whether or not you have a telescope, you will find yourself using binoculars often.  Rather than owning binoculars instead of a telescope, I recommend them in addition to a telescope.

This article will help you decide which binoculars are right for you.

Guidelines in a Nutshell:

1.  Buy 7x50's if it's dark where you live.  
2.  Buy 10x50's or 8x42's if it's isn't.
3.  If the first number (above) is bigger than 10, or the second number is bigger than 50, you can't hold them steady with just your hands for long.  Hello, tripod.  Nothing wrong with mounted binoculars, you can see a lot more with them mounted than without, but it does detract from their "grab & go" appeal.  (most 10x50's are pushing this limit too, get the lightest ones you can)
4.  If you have a chauffeur, you have enough money to consider a top quality brand roof prism type binocular such as Zeiss , Leica , or Swarovski .  Otherwise,  porro prism type binoculars represent the best value (and they can get pricey too!).
5.  It's all about grab & go.  Stay "neck strap portable".

Read on for explanations...

Why the Guidelines Make Sense:

I own five telescopes of various sizes. I use each of them in different situations. I also own two pair of 10x50 binoculars, and one pair of 8x42's ($120). One pair of the 10x50's cost about $150, and one pair set me back twenty bucks back in 1977.

I keep the $150 binoculars in their case next to the telescope I use the most often and they go outside when the scope does. Lately, I have been substituting the 8x42's for this purpose just because I like them better. I keep the other $20 pair in the kitchen next to the back door ready to grab and go whenever I want them. Guess which ones I use the most of all three?

That’s right, the cheap ones. Rubber eye cups worn away, lousy neck strap gone for years (thankfully), beat up looking, don’t really worry about them much, thirty year old "boat anchor" binoculars.  I love 'em!  Now days I suppose a similar pair would cost about $60, if that. I like my slightly more expensive pairs, and someday I would love some really expensive ones, but I don’t really need anything else.

The point is, they don’t have to be pricey to become your most often used tool. After going over a few considerations, I will give my recommendations depending on your budget, along with sources I like to buy from.


1. Magnification: Unless you plan on using a tripod you need to use binoculars with a magnification of 7-10 power ( 7x50, 8x42, 10x50, etc.). The first number is the magnification. Why not 12, or 15, or 20 power? You can’t hold them steady enough without mounting them.

2. Objective size: The second number in 7x50. In this case it represents a 50mm diameter of the front lens. 8x42 binoculars would have a 42mm objective. Go bigger than 50 and they are hard to hold steady (heavy). Smaller than 42 and they are usable, but you have pretty dim images for astronomy.

3. Roof or Porro prism: There are two basic designs to choose from.  Porro prisms of good quality are much less expensive to make than high quality roof prism designs. Porro prism binoculars also have a more 3D viewing experience. 

Roof Prism (image source)

Porro Prism (image source)


4. How dark is your sky: 7x50 binoculars will render a larger exit pupil and a  brighter image than 10x50’s or 8x42’s. If you have dark skies and you are under 40 years old (thus your pupils may still dilate enough to make use of a large exit pupil), 7x50’s are great. If your skies are a little on the bright side, or your older pupil maxes out at 5mm (exit pupil = Obj diameter/magnification) the other two choices will provide an image with more contrast and a darker background sky.

5. Field of view: The words “wide angle” are relative and should be taken with a grain of salt. Most binoculars for astronomy have a field of view of 5-7 degrees of actual sky. As long as your image has good contrast, you will be happy with any number in that range. Generally speaking, a super wide field of 7.5 degrees will not focus as sharp across the field (the image is focused in the center, but halfway out to the edge sharpness increasingly suffers) as a 5 degree field pair, unless you pay megabucks.

How Much Do You Want To Spend?

1.  My name is Elmer J. Fudd, millionaire, I own a mansion and a yacht:
Check out these brands. Zeiss , Leica , and Steiner . The first two have a lot of roof prism designs, but they are expensive enough to be of unmatched quality. The last one is in my opinion the best of the best in porro prism designs, though heavier than some. $500 and up for the Steiner’s, $1000 and up for the other two.

2.  I haven't won the lottery yet:
There are many brand name binoculars available from A-Z in the $200 to $500 price range.  A well known name doesn't always mean they are great, or better than a lesser name.  It depends on many factors such as weight, a trouble free focusing mechanism, comfortable eye cups that position the eyes properly if you wear glasses or if you don't, etc.. Just be patient, read lots of reviews for each pair you may think you like, and purchase from somewhere like Amazon with a trouble free return policy.

3.  Under $200:

Yes, you can get good binoculars for under $200.  Really.  They may not advertise them specifically for astronomy, they may not be waterproof, but they will work fine.  I find I rarely ever look at stars when it's raining.  Just remember my "Guidelines in a Nutshell".  I'll even make a recommendation for a specific pair that many in this hobby have given great reviews for.  Check out the Nikon AE 8x40's.  Optically they aren't Ziess or Stieners, but they are very good.  Mechanically, no complaints.  The focuser, very sound.  Available for about $125, and worth every penny.

Collinder 399, "The Coathanger"
(author: Roberto Mura)
(image source)

Now go and get yourself some binoculars for astronomy!  You won't regret it.

Thanks for the look,