Learn the Basics of Stargazing with Binoculars

This guide covers how to read the numbers, how to focus, how to hold them steady, and what to look at first.

What do the two numbers on binoculars mean?

The first number is the magnification and the second is the objective lens diameter in millimeters. A 7x50 pair magnifies seven times and has front lenses 50 mm across.

Divide the objective diameter by the magnification and you get the exit pupil. Nikon's guide compares it with a human pupil of about 7 mm in the dark. The closer the exit pupil is to that size, the brighter the view feels, close to what you see with the naked eye. A smaller exit pupil looks dimmer.

Checked on 2026-10-18. The exit pupil formula and the 7x50 and 8x20 comparison come from Nikon's binoculars guide, and the beginner range comes from NASA.

In short, for the night sky a larger second number helps, and keeping the first number at 10 or below makes them easier to handle. NASA also advises against starting with anything much more powerful than 10x50.

In what order do you focus?

Set the eye width first, then focus the left eye with the center focus wheel and the right eye with the diopter ring. Even if your eyes differ, this order makes both sides sharp together.

1. Hold the binoculars with both hands, look at something far away, and fold the barrels up or down until the two views merge into one circle.
2. Close your right eye, look with your left eye only, and turn the center focus wheel until the view is sharp.
3. Close your left eye, look with your right eye only, and turn the diopter ring on the right eyepiece until it is sharp.
4. Open both eyes. From now on, you only need the center focus wheel when you change targets.

Nikon's guide says that if the diopter ring is on the left eyepiece, you reverse the order. Since stars are extremely far away, it helps to set focus on a distant hill or building before dark.

How do you reduce shake?

Hold them with both hands and brace your elbows against your body. Here are the postures Nikon's guide recommends.

• Grip the barrels with both hands and keep your elbows against your torso.
• Gripping too hard actually makes your hands shake. Balance the binoculars between your index fingers and thumbs and wrap the other fingers loosely.
• If a tree or wall is nearby, lean your body against it.
• Resting the binoculars on a stump, fence, or rock also cuts down shake.

NASA says that the more powerful the binoculars, the more they jiggle in your hands. For long looks at one target or for 10x and above, you can set a tripod on flat ground and attach the binoculars with an adapter.

Which targets should you look for first?

Start with the Moon, then move on to bright clusters and nebulae. The list below includes only targets named in NASA's guide.

Checked on 2026-10-18, based on NASA's Binoculars: A Great First Telescope.

NASA explains that binoculars show a much wider field of view than most telescopes. That is why spread-out clusters fit in a single view.

What should you watch out for when heading out?

The most important rule is never to look at the Sun through binoculars. Nikon's guide warns that it can seriously damage your eyes. When you scan the western sky at dusk, wait until the Sun has fully set.

• Going straight from a warm room into the cold can fog the lenses. Nikon's guide says to avoid sudden temperature changes and to let fog dry naturally.
• Wipe dew off with a dry cloth, and clean fingerprints gently with oil-free lens tissue. Ordinary tissue and velvet cloth can scratch the lenses.
• Store them away from humid, hot places. An airtight container with a desiccant helps prevent mold.
• As covered in watching meteor showers with the naked eye, your eyes need about 30 minutes to adapt to the dark. Keep your phone screen dim during that time.

Before you go, check once when the Moon sets that night. Clusters and nebulae look much clearer after it has set.