Binoculars For Astronomy Buying Guide

Binoculars For Astronomy Buying Guide

Beginning stargazers will often overlook binoculars for astronomy, but as you become more experienced you’ll surely keep a pair close at hand as binoculars provide many benefits over telescopes. A good pair of binoculars for astronomy gives you that grab-and-go convenience on nights when you either just don’t have much time to bring out the big telescope and get everything set up or when you just want a quick view of the  night sky, even when you do have your scope out and ready you’ll notice, you will be grabbing for you favorite pair of binoculars to first scope out the night sky and pinpoint exactly what it is that you’ll want to focus your telescope on, even a modest pair of bins lets you see as many as 100,000 stars, hundreds of star clusters, nebulae and the remnants of a supernova along with dozens of galaxies Binoculars give you an expansive and relatively inexpensive view of the sky, as you can see with both eyes which is more comfortable and gives you a more expansive view of the night sky. Anyone interested in Astronomy should own a good pair of binoculars. Most avid stargazer with a houseful of telescopes will have at least one pair of binoculars at the ready!

It is often said that binoculars are the best “first telescopes”. They really are simply two small telescopes side by side, with a little extra optics magic to make the eyepieces close enough so you can comfortably look through both scopes at the same time. Binoculars are easy and intuitive to use, unlike larger telescope that can be overly complicated and frustrating for beginners, were as binoculars produce a right side-up image and provides a large viewing field which makes it easy to locate objects in the night sky, it also requires no aligning, you can simply grab your favorite pair, head outside and point them to the stars. Binoculars are especially useful for seeing large craters on the Moon, the moons of Jupiter and if you’re lucky enough the occasional comet, with time you’ll be able to pinpoint objects with easy, which will be very beneficial once you do get a telescope.

As we know for astronomy, more aperture is always better, in stargazing we are viewing stationary objects that are very far away, to make matters more complicated the environment also presents us with minimal light, therefore my personal recommendation would be to go a 10X50 pair of binoculars or 10×80 ( i.e ten times magnification on an 80mm objective lenses, the bigger the objective lens, the more light they can gather and the brighter the image you’ll see.) as higher aperture will allow us to see objects more clearly. But is there a trade-off? Bigger lenses means more weight, which makes it harder to hold for any length of time, for this reason I tend to mount my binoculars on a tripod.

You will always see binoculars being marked with two key numbers (Magnification and Aperture) for example a pair marked 10×50 magnifies 10x and has a lenses of 50mm in diameter, the bigger the optics the more detail and light gathering ability it has,  while a magnify of 6 to 10 is ideal of astronomy, personally my favourite configuration is the 10×50, they are generally light enough to hand hold for a short while and provide a good viewing experience, of course higher power means you’ll see more details but it also means that they will be bulkier and heavier, a higher magnification will also  narrow the field of view, and it’s harder to keep a high-power pair of binoculars steady enough to see fine detail since the slight shaking of your arms is also magnified. For hand-held a magnification of 7-8x is optimum, and 10x is maximum. Binoculars also allow viewing with both eyes. This is more comfortable and natural compared to telescope.

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  1.   1 When selecting a good pair of binoculars for astronomy stick with the porro-prism and multi-coated optics as these will offer the best viewing experience in low light settings, porro-prism are the classic type of binoculars where the lens is offset at about a 45 degree angle, we recommend these as the straight through or roof prisms are indeed a good pair but come at a price, better to take that extra cash and put it towards a higher end telescope, I personally would also avoid the zoom features and built in cameras as they don’t quite cut it for astronomy viewing.
  3.   2. Pick up a pair of binoculars and look at the light reflected in the objective lenses, now if they have a good anti-reflection coating they’ll appear mostly dark with a tiny bit of colour this it shows that they have good AR coating that’s what we want for stargazing, if the lenses are mostly ruby red or white stay away from these as they have no or poor coating and will show mostly ghost images and objects like the moon will be very fuzzy.

Orange or red coatings on the lenses are not acceptable for astronomical use.

  1.   3.Exist pupil and Magnification

Although the objective lens determines to a larger extent how much light enters the binoculars, it is actually the Exist Pupil that determines how much light enters your eyes, an important feature not be overlooked when one is selecting the best-suited binoculars for one’s self,

In darkness and poor lighting conditions, the maximum pupil size of a human eye is on average between 5mm to 9mm for people below 25 years of age,  7mm being the average and the maximum size is 9mm, this number will decrease with age, what this boils down to is an exit pupil smaller than your pupil will mean that you will perceive the image as being darker than it actually is due to the limited amount of light entering your eyes.

You may also want to consider if you are older than 50, you may not need the 7 mm exit pupil provided by 7×50’s, therefore you may consider 8×42’s which will give a slightly larger image.  If you don’t mind a little more weight, a pair of 8×56’s or 10×50’s are a great choices for stargazing. 10×50 being about the perfect balance between conformability and viewing quality. Any more than 10x magnification, and the image will get a little shaky.  Any bigger than 63 mm, and the binoculars will get too heavy to hold for long periods.

Another quick test is to hold a pair away from your face with the eyepieces towards you, now look at the disk of the exit pupil (check image) if the disk appears as a round prisms it uses high-grade glass called BAK-4 glass where is if the disk appears squared-off, the prisms are made from a lower-grade glass. Ideally and if it can be helped stick with BAK-4 grade quality, bas it not optimum.


Advantages of a Binocular

  •   1. Whilst most bins will have a lower magnification than a telescope, they are inexpensive compared to telescope and will allow you to gauge your interest without breaking the bank –
  •   2. Ideal why to start learning the key objects in the sky
  •   3. Advantage of a wider field of view making it easier to scan the sky, better for beginners
  •   4. More Portable
  •   5. Observing with both eyes not only feels more natural and comfortable

Binoculars are inexpensive, simple and easy to use, and yet bring in thousands of objects within our own Milky Way Galaxy, every stargazer should own a pair. But there will come a time when you want to see more objects brighter, bigger, farther way and in more detail.  That’s when you will want to consider a telescope.