Binoculars are invaluable for stargazing. But, like telescopes, there is lots to consider when you’re new to using them.
Binoculars provide better depth perception than telescopes, because you’re viewing targets using with tow eyes. They’re also usually more affordable, smaller, and lighter than most telescopes.
Even if you prefer a telescope as your main stargazing instrument, we often suggest keeping a pair of binoculars in your astronomy toolkit. If you’re starting stargazing with binoculars and heading out under WA’s wide night skies, keep reading for our simple tips.
Tip #1: Decode the binocular numbers
When you’re buying your first binoculars, our advice is start small and simple.
Aperture and magnification are important to know, but also consider how portable and manageable the binoculars are.
You will find that binoculars are always marked with two numbers, for example, 10×50. The 10 is the magnification, so the binoculars have ten times the magnification of the naked eye. The 50 stands for 50mm, which is the diameter of the binocular lenses.
Like with cameras and refractor telescopes, this is the aperture. The larger the lenses, the more light they let in, and the easier it is to see faint objects.
More powerful binoculars sound good, but how heavy are they? How easily will you be able to hold them steady when you get tired? A 10×50 pair is an excellent place to start when you’re an astronomy binoculars beginner.
Tip #2: Know your eyes
Knowing exit pupil and eye relief will help you get the best out of binoculars.
The exit pupil is the bright disc or bright circle of light you see in the centre of your binocular’s eyepieces. It should be about the same size as your eye’s pupil under dark conditions, between 4 and 8 millimetres in diameter. See this rough guide to the average human eye pupil diameter and age.
If the exit pupil is too small, you’ll miss the details of what you’re observing. But don’t overcompensate: with a too-large exit pupil, you won’t fully capture what you’re seeing.
Eye relief is the distance from your eyes to the binocular eyepieces. With higher eye relief, you can hold binoculars farther from your face.
This is especially important if you wear glasses, because your eye is farther from the eyepiece, you need that higher eye relief. There’s no magical number to this; it’s what feels right for you.
Tip #3: Know what you want to see
Starting stargazing with binoculars is easier when you have specific targets in mind. We recommend starting with the Moon, before checking out bright planets like Saturn and Jupiter, and exploring the Milky Way.
Pick up a Planisphere, turn the wheel until you match the date and time you want to go out, and see what’s up in the night sky.
Or, download a stargazing app, our favourites include SkySafari, SkyView, and Stellarium mobile. They give you plenty of information to start understanding the starry night sky. Like a planisphere, you can use them in real time to learn what you’re seeing in the sky, or enter a future date and time.
Tip #4: Experiment with your settings
Take your binoculars out in the daytime and experiment with looking at objects at different distances; notice how adjusting the magnification affects your view.
A higher magnification generally makes distant objects, like the Moon, appear closer and reveals surface details. Lower magnification gives a wider field of view, ideal for observing objects like nebulae or galaxies.
Get comfortable with your binoculars and find the right balance of magnification. You will feel more confident using them when you’re out stargazing.
Tip #5: Know how to look
If you look very slightly away from a faint object you want to observe, you’ll see it more
clearly. Using your binoculars, aim for your target to be near the centre of your field of view, then look at a spot a little bit above it.
This is averted vision, and it helps you see objects many times fainter than you can with direct vision, because of the structure of our eyes.
Averted vision uses the rods that are concentrated around the edges of your eye’s retina, rather than the cones in the centre. The rods work better in low-light, so they’re largely responsible for seeing in the dark. A drawback is that they can’t see colour.
Averted vision, looking away from faint objects, is also a great tip for meteor showers.
Jay Chesters
Jay Chesters is an award-winning wordsmith and science communicator with a little bit of a thing for the stars.
A cosmic storyteller with a love for astronomy and space that's out of this world, Jay’s always eager to share his knowledge and passions.
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