When you think about back garden stargazing, binoculars will probably be the first astronomy tool that comes to mind (aside from a telescope). They are cheaper and more portable than a telescope but can still give you a great view of the stars.
There is, however, an alternative. Meet the monocular. Essentially a pair of binoculars cut in half, making them lighter and more ergonomic. They are often much more straightforward than binoculars as they are only a single barrel with one objective lens.
Monoculars are a portable and travel-friendly alternative to a small telescope, though they don't provide the same level of magnification. They're often associated with bird-watching, hunting and hiking, though a good monocular can boost your astronomy experience too. If you're serious about stargazing, you'll need to stick to the best telescopes or a set of good binoculars, but if you need to save on space and weight, there are good monocular options.
To use a monocular for astronomy, you'll want to look at 40-50mm objective lenses with 7-15x magnification - anything smaller is better suited to wildlife spotting. Some monoculars have built-in image capture while others offer smartphone mounts for super-easy 'digiscoping' and a built-in tripod mount. Since you're going to be using them outside it's sensible to choose a monocular that has waterproofing and fog-proofing, too, especially as you'll likely be pulling it out of a warm bag or pocket to use in colder air. Here at Space.com, we've cast our eye over the market for the best monoculars and rounded up our favorites for all kinds of astronomy.
Best for wide-angles
Opticron's compact and lightweight Explorer WA ED-R 8x42 is a great choice for a stargazing monocular. Its 42mm objective lens lets in plenty of light while keeping the unit small for hiking and backpacking, it is easily pocketable. The 8x magnification (a 10x model (opens in new tab) is also available) is similar to what you’d find on many binoculars and gives a great view of sections of the night sky. Also making it easier for beginners to seek out their subjects.
The Opticron BGA WP 8x42 is waterproof to 3m and nitrogen-filled, so fog and condensation proof. It comes with a soft neoprene carry case with rain guard, padded strap and rubber objective lens covers. There is 17mm of eye relief so suitable for glasses wearers.
The optics feature the latest multi-coating technology throughout the wide-field ED optics, so it displays plenty of contrast, clarity and a premium feel, despite the modest price tag.
Best for weight saving
This lightweight 10x42 11.5oz/32KG monocular is ideal for travelers who want to enjoy the night sky while out and about.
Despite its portability, Hawke hasn't scrimped on the glass. It's fitted with Hawke's System H5 optics, with extra-low dispersion (ED) glass to reduce color fringing and multi-coated lenses.
It's built to withstand the elements and comes with a waterproof chassis, high grip armoring, protective lens case, lanyard, lens covers and a built-in 1/4-inch tripod thread. It also comes with a no-fault lifetime warranty which is pretty impressive!
Best for glasses wearers
The Opticron Oregon 4 PC 8x42 are Nitrogen-filled to eliminate fog, and waterproof, making them the perfect option for those who need a hardy all-weather monocular. It has a 42mm objective lens allowing just enough light in for general astronomical use. The 8x magnification guarantees you get a good, stable view when sweeping across the night sky.
The roof prism design is all about wide-field viewing and top-quality optics. It has phase-corrected prism coatings and multi-coated optics to deliver clear, crisp views daily and in low light. The monocular incorporates an external focuser for easy single-handed operation, though it lacks a built-in 1/4-inch tripod adaptor. Wearers of glasses will appreciate its very generous 22mm eye relief.
Best for accessories
The Bushnell boasts exceptional optics, build quality and extras. The magnification of 10x, coupled with a 42mm objective lens, means you'll get crisp, detailed images, enhanced by Bushnell's ED Prime HD glass, multi-coated and anti-reflective optics.
Its twist-up eyecups offer great eye relief for those who wear glasses, and there's even an easy-to-grip ridge on top of the external focuser where your thumb would naturally rest.
The Bushnell Legend Ultra 10x42 stands out from its competition by shipping a top-quality padded case complete with a belt clip, a flip-style lens cap for the front, and a rear lens cap that attaches via a lanyard to prevent it from being misplaced.
Best for magnification
If you want to zoom in on anything, including the night sky, with your smartphone, the only accurate method (at least until periscope-style zoom lenses become common on cellphones) is to use a digital zoom. Using a digital zoom means the image is cropped, then rebuilt it to its original size using algorithms or machine learning. It almost always results in a poor-quality image.
A far better option is a clip-on lens like this BAK4 roof prism-based monocular for its superior optics. It is essentially a tiny telescope with a fixed zoom of 36x, the Apexel 36x superzoom can be used hand-held but is best on a tripod. A far better option is a clip-on lens like this BAK4 roof prism-based monocular, for its superior optics. You fit a clip around your smartphone's existing lens before attaching it to the Apexel 36x super zoom to align them.
It's not perfect, you first need to remove your smartphone's case and there's no tripod thread built-in, instead, a metal tripod ring adaptor is supplied. In any case, the tripod it is bundled with is quite flimsy. Supply your own tripod, and the Apexel 36x superzoom can be a good setup for taking basic images of the Moon (though don't expect it to fill the field of view). You can use it as a monocular by attaching a small rubber eyepiece, but remember, this does restrict the field of view.
Best for using with a smartphone
Attaching a cellphone to a telescope so the phone's camera peers down the barrel to see a magnified view is called digiscoping. The camera can produce some excellent images of distant ducks during the daytime and the sky at night.
The Celestron Outland X 10x50 comes with a smartphone mount and could be considered an ideal digiscoping companion with its astronomy-centric optics. The 10x magnification and 50mm objective lenses are well-suited to searching for and studying, open star clusters, the Moon, and the Milky Way.
Built around BAK-4 prisms, the Celestron Outland X 10x50 feature multi-coated optics and have plenty of eye relief, so it can be used easily by anyone who wears glasses. It's also waterproof and filled with nitrogen gas to prevent internal fogging.
Best for travelling light
A zoom monocular capable of magnification from 8x to 42x, the Olivon 8-24x40 is capable of both observations and basic photography. Its magnification is excellent for observing the Moon's craters and lava seas, while it's small and light enough to take out and about on a lanyard and pouch (both supplied).
The BK-7 prism-based monocular with a push-pull zoom arrangement comes with a built-in 1.4-inch tripod adaptor to stabilize it, an easy-grip rubberized coating and multi-coated optics. It can also be work as a simple digiscoping option. When used for wildlife spotting, the Olivon 8-24x40 offers close focus from 60”/1.6m.
Best for Moon-viewing
Slightly more expensive than the Olivon 8-24x40 comes the Orion 10-25x42, another variable zoom monocular that offers 10x through 25x magnification and a slightly larger objective lens.
As such, it's another option for impressive lunar viewing, with just a touch more magnification than its lighter rival. Since it doesn't have quite as wide an angle of view, it can focus on subjects just 20”/50cm away while offering 25x magnification. The 42mm objective aperture lens makes it very versatile for daytime, low light or nighttime use. You shouldn't have any problems getting a closer look at the moon craters.
The Orion 10-25x42 is rugged. Its waterproof with a rubberized design and features multi-coated optics. It ships with a soft nylon case (complete with belt loop) and a wrist strap.
Best for wildlife
It is always tempting to go for the most enormous magnification possible when looking at a new optical instrument, but this isn't always the best choice. Higher magnification means more weight and the need for larger objective lenses to maintain a bright view and the ability to use at night. It's also much more challenging to get a steady image (as the magnification also magnifies any movement). Moderate magnification factors of around 8x are preferred.
The 15x magnification of incredibly expensive Vortex Recon R/T 15x50 will give you a closer look at objects than your average pair of astronomy-centric binoculars or monoculars. However, at night, that extra magnification creates a narrow exit pupil, which reduces the image's brightness, despite the Vortex Recon R/T 15x50's large 50mm objective lens.
So what is the Vortex Recon R/T 15x50 for in terms of night-sky viewing? The Moon. With its multi-coated extra-low dispersion glass, you can expect detailed and high-resolution images at long distances. It comes with a hand-strap and a carry clip that you can use to attach the monocular to a belt or bag.