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Using Binoculars in Amateur Astronomy (Best Options)

In addition to a great telescope, you may want to invest in a good set of binoculars for astronomy. There are many reasons why. I cover these, and in case you are wondering what are the best binoculars for stargazing, I go over the basics you need to know.

Table of Content

Why Use Astronomy Binoculars?

One reason…

…not only can you use the binoculars for astronomy, but you can also use them as bird watching binoculars and for other terrestrial pursuits. This makes them cost-effective and a good option for kids or beginners keen on stargazing.

Another reason…they are portable. But then so are some telescopes.

They are also easy to set up.

Thus, recommending binoculars for astronomy beginners makes sense.

But here’s the deal…

Wide Field of View

It’s not simply a matter of binoculars vs telescope. A set of good quality binoculars will provide you with a wider field of view than a telescope and so make a great accompaniment to that best telescope for stargazing.

Viewing the night sky with binoculars means you will see a larger portion of the sky than through a telescope.

binoculars and telescopes work together

Binoculars are useful for helping you find your celestial object. Moreover, they assist in getting you acquainted with the night sky, with the positioning of stars, planets, and constellations.

With a good set of astronomy binoculars, you can see larger objects like the double cluster in Perseus, star clusters of the Pleiades and Hyades, and even galaxies better than you can with a telescope because you see the object in context, with the black sky around it.

So, not only is a pair of astronomy binoculars great for checking out the craters on the moon, but they have many uses in astronomy (my list of 10).

12x40 Binoculars for astronomy, view of moon,
The moon viewed through binoculars 12 x 40

Astronomy Binoculars Buying Guide

Which binoculars for astronomy are the best? Looking through a long list of binoculars for sale can be overwhelming. This guide aims to give you some ideas of what to look for in binoculars for astronomy.

Features of the Best Binoculars for Astronomy

Which binoculars are best for astronomy? In choosing the best astronomy binoculars start with an aperture of no less than 50 mm and a magnification of at least 7. Other factors to consider are the quality of the optics, the lens coating, the exit pupil value, and the eye relief (for comfort in use).

So, one…the size of the aperture matters. And, two the power (magnification) of the binoculars is important. But there’s more to consider if you want the best binoculars for the money for stargazing.

Considering Aperture

A 50 mm diameter objective lens in binoculars for astronomy is a fairly popular choice for amateur stargazers.

A 50 mm diameter objective lens means a high light-gathering ability, ideal for astronomical use. This size objective lens is a good place to begin for comfort at least since a larger lens becomes weightier, when handheld.

Still, more aperture is useful for astronomy. You’ll see fainter stars with a 10×80 mm, for example, than a 10×50 mm. But, the larger the aperture the likely bigger and bulkier will be the binoculars. You can use a tripod to help with this (I talk about this further down the page).

Magnification Limitations

What is the best magnification for stargazing binoculars?

If you are wanting binoculars to buy for astronomy, a power of 7× is okay and a good start. Handheld binoculars astronomy wise, can be uncomfortable when they get above 10 times in magnification.

Even with a 7× or 10×50 set of binoculars, astronomy wise, keeping them steady is a task when handheld. You will need to use a tripod or other methods (see binoculars best ways to steady them below) to stop the shaking and get a clear view.

The higher the magnification the better detail. But, with higher power comes lower field of view. Something to weigh up.

Optics

You’ll want binoculars with decent optics.

Look for binoculars that hold the focus out to the edge of the field of view, when focusing an object in the center of that field. It doesn’t have to be perfect – what you don’t want is the edge being way out of focus or highly distorted.

This is to do with the precision of the lens shape.

Optical Prisms

The purpose of the prisms is to rotate the view the right way up.

The two types of prisms you need to know about are the roof prisms and Porro prisms.

Porro Prisms

Look for binoculars with Porro prisms, which give brighter images than roof prisms with the same objective size, magnification, and optical quality. Thus, a good set of roof-prism binoculars for astronomy can be more expensive.

The Porro-prism binoculars are wide because, in these, the objective lenses and the eyepieces are offset.

Roof Prisms

In contrast, the view through roof prism binoculars is straight through because the objective lenses and the eyepieces are in line rather than offset. These are the narrow types and make the best compact binoculars.

You should consider the quality of the glass in the prisms. The optimum type is BAK-4 rather than the more inferior, but satisfactory, BK-7, for example.

Lens Coatings

In modern binoculars, performance in low light conditions, such as twilight, can depends on the quality of the optical coatings.

Anti-reflective (AR) coatings work to reduce the amount of light being lost through reflection. In binoculars without AR coating, you can lose up to 5% of light transmitted in binoculars. So the AR coating helps improve light transmission through the binoculars.

Modern lenses are coated with complex multi-layers of anti-reflective material.

To look for anti-reflective coating, pick them up and look at the light reflected in the lenses. According to experienced users, a good AR coating would mean the lenses are dark but with some reflected color. Avoid ones where the lenses appear white or ruby red. A white surface indicates no AR coating and ruby-red a highly reflective coating that limits brightness.

Complexity of AR Coatings

There are different types of AR coatings and manufacturers generally describe these as either fully multi, fully, multi or coating.

Fully multi-coated generally means multiple layers of coating on all lens surfaces. Fully multi is found on high end optics.

Fully coated can mean a thin AR coating on both sides of both the objective lens and the ocular lens systems, as well as the length of the prism.

Multi-coated indicates there are multiple layers of coating, but not necessarily on all lens systems.

And coating suggests a single coating only, usually of magnesium fluorite.

Zoom or Built In Camera

According to experienced users, a built in camera or zoom don’t make the grade if you are wanting a pair of binoculars for astronomy.

Binocular Field of View

This is often given as how many degrees that can be viewed or a linear measure of width that can be seen at a thousand yards (e.g., feet @ 1000 yds).

Binoculars offer a wider field of view than a telescope (< 1º) and thus, why they have a purpose in astronomy.

A typical pair lets you see 5 to 8 degrees of sky, about the width of four fingers held at arms length.

The Editors of One-Minute Astronomer. 2009

Exit Pupils

The exit pupil is the objective diameter (mm) over the magnification (EP = D/M). So, for example, a set that is 7×50 (that is, objective diameter of 50 mm and a magnification of 7) will have an exit pupil of about 7 mm.

Look for a exit pupil value that is at least equal to the diameter of your dilated pupil at night. Interestingly, what to look for in this instance is age-related.

But, remember that the best exit pupil for you will depend on your age.

For those under 30, the average exit pupil is 7 mm. It reduces with age, so an exit pupil of between 5 to 6 mm might be more relevant for 50 years and older. If you are an older user, to avoid loss of light reaching your eyes (plus unneeded expense), a set of binoculars  7×35 or 7×42 would be better suited for you.

Eye Relief

This is about comfort and seeing the entire field of view, and can make a difference with holding the binoculars steady.

Eye Relief for Eye-Glass Wearers

If you need to wear glasses look for a minimum of about 16 mm or more. Naturally, it will depend on you and your glasses.

Eye relief length is especially important if you wear glasses for astigmatism. You don’t need to wear glasses if you are near- or farsighted since you can adjust the focus of the binoculars to account for these sight issues.

Eye relief of binoculars is usually between a few millimeters and a few centimeters. When wearing glasses, the longer the eye relief, the better the fit for comfort and the better will be your ability to see the entire field of view.

Changeable Eyepieces

There are at least three lenses in each binocular eyepiece. The field lens is farthest and the eye lens is closest to the eye.

Some astronomical binoculars have changeable eyepieces that change the magnification.


Reviews of Best Binoculars for Stargazing

For astronomy binoculars, Amazon has a great range to choose from including some best binocular brands. Among the brand names are Nikon, Orion, and Celestron astronomy binoculars. Here we look at two Celestron binoculars for skywatching.

Cometron 7×50 Celestron Binoculars Review

A set of beginner astronomy binoculars, 7×50, like these will give you a field of view of about 7 degrees in diameter. Compare this to a typical amateur telescope (even when using low power) with a field of view of only 1 degree. This translates to 40–50 times the area being visible with this pair of binoculars compared to the telescope.

This Celestron set is water resistant, which is what you need for outdoor use, especially at night when you are likely to experience dew or mist.

With a 50 mm objective lens, the field of view is 357 feet at 1000 yards. The lenses are multicoated with large exit pupil (7 mm). The distance between the centers of the pupils (IPD) is 56–72 mm and close focus distance, which is the closest point that the binocular can focus on, is 26.2 ft. Eye relief is 13 mm with a folding eyecup.

Housing is aluminum. Accessories include carrying case, objective and eyepiece covers, and lens cloth.

This is a Porro-prism binoculars set (objective lenses and eyepieces are offset). The prism material is BK-7.

This Celestron set comes at a price in the range seen for the best budget binoculars for astronomy.

Pros: One of the best binoculars for the price for beginners with features of a large pupil exit (best for under 30s), Porro-prisms, and AR coating.

Cons: Not optimum for those who need to wear glasses (i.e., those with astigmatism) given the eye relief of 13 mm and older users would be better with a pupil exit of 5–6 mm. Also, if you want a higher grade prism material, look further and consider paying more.

Price

Get the latest price of the Celestron 7×50 Binoculars at AmazonSee details.


Celestron SkyMaster Giant 15×70 Binoculars

Binoculars Celestron Skymaster Giant 15×70

The field of view is 231 feet at 1000 yards or 4.4° for these binoculars Celestron make with a 70 mm objective lens and 15 magnification.

The long eye relief and soft rubber folding eyecups make this ideal for wearers of glasses and with an exit pupil of 4.66 mm, one of the best binoculars under 100 dollars for mature astronomers.

Users have claimed that galaxies, like the Andromeda, are easy to spot with these binoculars, with one noting the view of face-on spiral galaxies was better than with a 10″ telescope.

The optics are multi-coated.

This is a Porro-prism binoculars set (objective lenses and eyepieces are offset). The glass material is high index BAK-4. Close focus distance is 47.2 feet.

It comes with many accessories, like lens covers, rain guard, carrying case, neck strap, and cleaning cloth. It does not come with a tripod but can be used with a tripod.

This Celestron binoculars set is also water resistant.

Pros: Constructed with high-grade prism material, BAK-4, which is optimum, inferring better light transmission and edge-to-edge sharpness. Great for wearers of glasses given the long eye relief. Especially suited to older users with the pupil exit of 5 mm.

Cons: Doesn’t come with a tripod, though it is tripod adaptable. With an objective lens of 15, use of a tripod is recommended.

Price

See the latest price on the Celestron SkyMaster Giant at Amazon. See Details.


How to Use Binoculars for Astronomy

I think everyone would or should know the basics of using a pair of binoculars. There are three things that can cause you a little bit of frustration with those good astronomy binoculars. One is focussing, two is image stability, and three is finding the object.

Focusing the Binoculars

I go over the basics of focussing in How to Set Up Binoculars, further down.

Binoculars Best Ways To Steady Them

You need to keep the binoculars steady for a clear view. You can try to brace yourself by placing your elbows on a table, a railing, or the roof of your car.

One option is to buy a mount to hold the binoculars steady. If you have a camera tripod you can add a bracket that is designed to attach to it.  This will be a cheaper option than buying a specific astronomy binocular tripod.

The SnapZoom Universal Binocular Tripod Mount is useful because it suits all. That is, you can use it with binoculars that don’t have that threaded tripod socket.

You can get this mount at Amazon. Check out the latest price here.

Binoculars with Image Stabilization

Image stabilized binoculars will avail a steady experience and stunning views without the shake. These binoculars have sensors that detect movements in high or low light conditions.

The downside of these is the battery usage. And, then the price.

Finding the Object in the Night Sky

People tend to look lower than the object they wish to focus on when using their binoculars or telescope for astronomy. Practice helps with this. Try tipping the binoculars up.

Sometimes it’s easier to first find an object that stands out and then star hop across to where you want to go. I find using a tree or some other landmark as a pointer to the object and then moving your binoculars up to the object also helps.

It’s a good idea to practice on bright objects first until you get the hang of it.

It’s also best to plan your timing as it is difficult to look directly up with binoculars especially with a tripod. You might want to get comfy and lay back in a reclined seat or on a rug on the ground while hand-holding the binoculars if you are wanting to study the center of the sky.

How Do Binoculars Work?

They are optical instruments based on binocular (two-eyes) vision. Think of a set of binoculars as two telescopes put together to focus on the same point. The following is a basic overview.

The binoculars have two lens elements, one in front of the other, in each scope. The lenses capture and bend the light to give you a magnified view of what you are looking at. The first lens is the ‘objective’ lens. It captures the light from the distant object and the second lens element that sits behind it, magnifies the focussed image produced behind the first lens. So that you see the image the right way up, the binoculars have a prism (a roof or a Porro prism) inside to rotate the image.

How to Set Up Binoculars

Getting the binoculars ready for viewing can be done in less than 20 seconds.

Time needed: 1 minute.

How to set up binoculars in 3 easy steps:

  1. Right lens – focus binoculars

    Place a lens cover over the right lens (or close that eye) and focus the binoculars.

  2. Left lens – adjust eyepiece

    Switch to left side. With left lens covered (or eye shut), adjust the eyepiece ring until the image is sharp.

  3. Ready to go

    Remove the lens cover or open your eyes and you are ready to go

Final Thoughts

How to choose binoculars?

Here’s the deal…

For the best binoculars for astronomy, look for these features:

  • A complex anti-reflection coating
  • Porro prism – if you want better bang for buck
  • A high-grade glass, such as BAK-4, in the prism system
  • Precision of the lens shape
  • Consider at least a 7x magnification and 50x objective lens diameter

In the end, what you buy in binoculars will depend on your budget. How much do you want to (or can afford to) spend? And, do the binoculars have the features to satisfy you to get use of the binoculars astronomical wise?

Other features to consider:

  • Zoom or in built camera or not (recommended to avoid)
  • Exit pupil (age-related)
  • Eye relief (especially if you wear glasses)

How to Buy Binoculars?

Where to buy binoculars for stargazing? You can buy binoculars online. Some of the best cheap binoculars for astronomy can be found at Amazon.

Info Sources

Information about Astronomy Binoculars for Beginners was gathered from owners of astronomy binoculars, as a source for the best binocular reviews and publications:

  1. The Editors of One-Minute Astronomer. 2009. Stargazing for Beginners. A Binocular Tour of the Night Sky (v1.5). Mintaka Publishing.
  2. English, Neil. 2014. Grab ‘n’ Go Astronomy. The Patrick Moore Practical Astronomy Series. Springer.

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6 thoughts on “Using Binoculars in Amateur Astronomy (Best Options)”

  1. How do you take Astro images through the binos? Like the Moon pic you have included. Thanks in advance and thanks for taking the time to write this article, its very helpful.

    • Hi Caroline,
      With that particular photo, the photographer used a Nikon Coolpix P5000 in a focal behind a 12×40 set of binoculars. The image was then treated (or enhanced) using the software, GIMP.
      If you are looking to do it yourself, make sure your binoculars are stable, e.g. set up on a good tripod. Then look through the binoculars and focus the moon.
      You can use a camera or your phone for the next step.

      If you are using a camera, you will need to stabilize it as well – simply set it up on another tripod. A small pocket-sized camera will have a lens small enough to fit on the eyepiece of the binoculars. Align the camera lens with one eyepiece of the binoculars. You can use the zoom feature on your camera to get a nice enlarged image of the moon. Try setting the flash to off. Set the timer on the camera to a min or two to avoid camera shake. The Moon is bright, so try the lowest ISO setting and see how you go.
      A thing to note is that the Earth is continually rotating and so the image of the moon will move and you will need to adjust the binoculars and/or camera in a short time. This is the tricky part that may take practice and patience.

      If you intend using your iPhone/Android phone, you will need an attachment for the binoculars that aligns the phone with the eyepiece. These attachments are available on Amazon or other stores catering to digital technology. Check out owner reviews on Amazon regarding a good one to suit your binoculars.
      I hope this helps. The main thing is to just do it!
      regards Jeff

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