The best telescopes are designed to transport astronomers to the heavens, aiding with stargazing and bringing glorious galaxies, nebulas, planets and other deep sky objects to our eyes in unparalleled depth and detail.
But which telescopes are the best and is there one telescope you should pick over another? To save you time trawling the internet our expert panel tests and reviews all manner of telescopes so you don't have to. We've reviewed everything from entry-level models to advanced instruments across a wide range of different types including refractors, reflectors, catadioptric telescopes like Maksutov-Cassegrains and even more newly developed smart telescopes.
So whether you want to view and take astrophotographs of the night sky from your smartphone, travel to a dark sky site with a more portable telescope or want to hunker down with a massive Dobsonian, we've got you covered.
If you're not sure what all the telescope jargon means, scroll to the bottom of this page, where we have explained all you need to know in our Telescope FAQ. You can also use the navigation bar on the left to switch between categories if you already have some idea of the type of scope you're looking for — beginner telescopes, computerized GoTo, smart telescopes, best scopes for astrophotography and more.
At Space.com, we don't just review telescopes. We also have a full guide on the Best binoculars. And if you're looking to pair a telescope with one of the Best cameras for photos and videos, we've got you covered there too.
Amazon Prime Day is just around the corner and we will be posting the best deals as we see them so keep an eye on the site for the best Amazon Prime Day telescope deals. That said, under each product below, you'll always see the best live prices for each product at any given time.
Best telescopes 2023: For stargazing galaxies, nebulas and more
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The Celestron NexStar 4SE is a great option for beginner astronomers. It is easy to use, produces clear and bright images, and comes with a chunky and tactile hand controller. The field of view is somewhat limited, but this is not a deal breaker as the SkyAlign software and GoTo system make it easy to find objects. The hand controller also allows for nine different slewing speeds, which is great for making small corrections or scanning the night sky quickly.
One thing to keep in mind is that the NexStar SE scopes are power-hungry. It is advisable to use an external power supply, as a pack of AA batteries will not last long. This does limit portability, but it is not a deal breaker if you are willing to carry a portable power bank or power station.
Overall, in our Celestron NexStar 4SE telescope review, we found it to be a great telescope for beginners. It is easy to use, produces clear and bright images, and comes with a variety of features that make it a great value for the price.
- Read our full Celestron NexStar 4SE review
The Celestron Inspire 100AZ is an excellent telescope for beginners and those on a budget. It comes with a comprehensive set of accessories, making it a great value for the price and it's well-built and easy to use too.
The telescope itself is well-built and easy to use. It has a 100mm aperture, which gives it good light-gathering power. This allows you to see faint objects like galaxies and nebulae. The telescope also has a long focal length, which gives you a good magnification. This is perfect for viewing planets and other close-up objects.
The Inspire 100AZ comes with a variety of accessories, including two eyepieces, a red LED flashlight (for preserving night vision), an accessory tray, a StarPointer Pro finderscope to make it easier to find your subject, and a smartphone adapter for basic smartphone astrophotography.
Overall, the Celestron Inspire 100AZ is an excellent telescope for beginners and those on a budget. It's well-built, easy to use, and comes with a comprehensive set of accessories. During our Celestron Inspire 100AZ review we found a small amount of false color (purple color fringing), and a slight blurring in the field of view was noticeable. The latter is easily resolved with a careful selection of eyepieces, so we recommend investing in one of the best eyepieces to make the most of the Inspire 100AZ's optical system. The slight amount of false color shouldn't dampen your experience unless you are particularly fussy about color accuracy being spot on.
If you're looking for a telescope to get started with astronomy, the Inspire 100AZ is a great option.
The Celestron Astro Fi 102 telescope is a great option for beginners who want to start exploring the night sky without any prior astronomy knowledge. It is lightweight and portable, making it easy to transport and set up. The telescope also comes with a SkyPortal app that makes it easy to find and identify over 100k celestial objects.
The Astro Fi 102 is a Maksutov-Cassegrain telescope, which means it has a large aperture and a long focal length. This combination gives it good magnification power, making it ideal for viewing planets. The telescope also has a wide field of view, which makes it great for viewing star clusters and nebulae without having to adjust the scope's position too much.
As discussed in our Celestron Astro Fi 102 telescope review, it is not without its flaws. The finish is a bit plasticky, and the materials used are not the best quality. However, these flaws are outweighed by the telescope's portability, ease of use, and good optical performance.
Overall, the Celestron Astro Fi 102 is a great value for beginners who want to start exploring the night sky quickly. It is lightweight, portable, easy to use, and has good optical performance.
- Read our full Celestron Astro Fi 102 review
Best telescopes for enthusiasts
The Celestron NexStar Evolution 9.25 is a high-end GoTo telescope that offers stunning views of the night sky. It is equipped with a large aperture Schmidt-Cassegrain optical tube and a sturdy single-fork arm mount. The mount is motorized and includes a rechargeable lithium-ion battery, which allows for up to 10 hours of continuous use. The telescope also comes with a variety of accessories, a red dot finderscope, star diagonal, accessory tray, an international AC adapter, a hand control, and 13mm and 40mm eyepieces.
The NexStar Evolution 9.25 is the ideal choice for experienced skywatchers who are looking for a high-quality telescope that offers a complete tour of the universe. It is also a good choice for astrophotography, as the motorized mount can track objects as they move across the sky. Built into the mount is the telescope's very own Wi-Fi network, allowing you to connect and control the instrument via the Celestron SkyPortal app (downloadable for free on iOS and Android) — leave your chunky hand controller at home!
The only downside of the NexStar Evolution 9.25 is its weight. It is a bit bulky and difficult to transport, so it is best suited for backyard use and not moving around too much. However, this is a small trade-off given the telescope's robust and high-quality design.
Overall, the Celestron NexStar Evolution 9.25 is an excellent choice for experienced skywatchers who have the money to spare for a high-end GoTo telescope.
- Grab a bargain over on our Celestron Binocular and Telescope deals page
When we reviewed the Celestron Astro Fi 130 telescope we liked it a lot and think it's excellent value for money. While it's not necessarily a budget telescope, it is a lot more affordable than a few of the other telescopes in this guide, we think it's excellent value for money.
If you're new to stargazing, or even if you just don't have a lot of experience, this telescope can give you an astronomy experience to marvel at using telescope technology and good optics, serving as a virtual guide to the night sky.
A 130mm aperture allows more light to reach the telescope's eyepiece, making it easier to see faint objects in the night sky. A focal length of 650mm provides a wide field of view, so you can see more of the sky at once.
This telescope is sturdy and lightweight, making it easy to transport. It comes with a stable tripod, a red dot finder, and eyepieces, which makes it a great value for the price.
The Celestron Astro Fi 130 is a great telescope for the price, but there are a few things that could be better. The battery life is a bit short, and the eyepieces aren't the best quality. We think you should consider upgrading the eyepieces for a better experience, but for value for money, we highly recommend this scope.
- Read our full Celestron Astro Fi 130 review
Best Computerized or GoTo telescopes
The Celestron NexStar 8SE is a great telescope for beginners and experienced astronomers alike. It is easy to use, yet powerful enough to allow for deep space exploration and astrophotography.
The NexStar 8SE by Celestron is renowned and has earned the title 'The World's most beloved telescope.' It is the number one bestseller on B&H Photo. Featuring StarBright XLT optical coating, this telescope provides unparalleled clarity and contrast for viewing planets and the moon. Jupiter's moons, Saturn's rings, and other deep-sky objects are breathtakingly vivid through the Celestron NexStar 8SE's 203.2 mm aperture lens. The image is free of chromatic aberration and color fringing, providing stunning views of the night sky.
In our Celestron NexStar 8SE review, we walked you through what it's like to get everything set up, and it's very straightforward. No prior knowledge of the night sky is needed, as you can use Celestron's SkyPortal app or any other stargazing app to help you find two stars for the alignment process.
Once the telescope is aligned, you can use the handheld controller to point it at any object in its massive database. This includes planets, galaxies, double stars, star clusters, and nebulae. The 'sky tour' is a great option for beginners and indecisive people, as it automatically points the telescope at different interesting cosmic objects.
The motor runs smoothly, and the results are precise. Automatic tracking is a dream for astrophotographers, enabling them to take long exposures, which can then be stacked post-shoot to create beautiful images.
The Celestron NexStar 8SE is a high-end telescope that comes with a hefty price tag. However, it is well worth the investment for those who are serious about skywatching or astrophotography. While the NexStar 8SE may be too expensive for casual astronomy enthusiasts, it is an excellent choice for those who plan to engage in these activities for the long term.
- Read our full Celestron NexStar 8SE review
As an introduction to the world of GoTo skywatching, the Sky-Watcher Skymax 127 SynScan AZ is a must-have for observers on a tighter budget. The SynScan AZ hand controller offers information on over 40,000 astronomical objects, which includes the most complete catalogs (Messier, NGC, IC and SAO) of deep-sky and solar system targets.
The astronomer is well-equipped for a successful night under the stars. They have a good quality star diagonal, a 2x Barlow with a camera adaptor, a 6x30 finderscope, a stainless steel tripod, and an accessory tray.
Assembling the instrument is easy and, given the weight of 39.7 lbs. (18 kg), the Sky-Watcher Skymax 127 SynScan AZ is light enough to carry across the backyard without a great deal of effort. Skywatchers have the choice of powering the Servo Drive with 8 AA batteries or a 12V power supply — because batteries tend to drain quickly when cold, we recommend investing in the latter for uninterrupted observations with the SynScan technology.
Aligning the Skymax 127 is a simple process, but it may take some practice for beginners to get it just right. We recommend becoming familiar with the telescope before dark by reading the manual from cover to cover.
In terms of optical prowess, we don't have any complaints. We can fit a waxing gibbous moon phase in the field of view and, after tweaking the focuser, the craters and lunar mare come into exquisite focus, with lovely contrast and clarity. A moon filter offered even better sights. Slewing over to the star-forming region, the Orion Nebula (Messier 42), is also picked out easily with the 5-inch (127 mm) aperture — it appears as a dusty patch of light with the Trapezium Cluster's member stars dazzling with brilliant clarity at the nebula's heart.
The stainless steel tripod can be a bit unstable. To help prevent your telescope from tipping over, we suggest supporting/weighing down the setup while slewing in windy conditions.
- Need more advice? Here's our specialized guide to the best telescopes for beginners
Celestron's range of NexStar telescopes has a well-deserved reputation for excellent optics, user-friendly assembly and a plethora of features. The telescope exemplifies all of these which we outlined in our Celestron NexStar 6SE review.
If you're looking for a telescope with great light-gathering capabilities and a vast selection of astronomical objects to explore, this is an excellent choice. The 5.91-inch (150 mm) aperture provides superior performance compared to the Meade StarNavigator NG 114, while the NexStar+ hand controller contains an expansive database with over 40,000 objects. Unfortunately, extra eyepieces will need to be purchased in order to get the most out of the telescope, and even then, not all objects listed in the database can be viewed in great detail.
The NextStar 6SE is a great telescope for exploring the night sky. It has a built-in tour mode that guides you to different celestial objects, either across the entire sky or within specific constellations. This is perfect for beginners who don't know what to look for, or for those who want to get straight to observing interesting objects.
The SkyAlign technology is easy to use and quickly gets you pointed in the right direction. The motorized mount also has nine slewing speeds and different tracking rates. All of this sounds great, but there is a downside. The NexStar 6SE's battery can drain very quickly, so we recommend powering the setup with an external power source.
Astrophotographers may initially be displeased with its slow f/10 focal ratio, limiting the NexStar 6SE to being a planetary or lunar imager at best. Still, there is the facility for more advanced users to switch out the secondary mirror for their camera, increasing the focal ratio to an astrophotography-friendly f/2.
- Read our full Celestron NexStar 6SE review
Best Smart telescopes
The Unistellar eQuinox 2 is the latest and greatest smart telescope from Unistellar. It is a successor to the popular eQuinox model and features a number of improvements. In our Unistellar eQuinox 2 review we tested it for ease of use, robustness and compatibility with smart devices and found the smart telescope to be eminently usable, not least because of its Smart Light Pollution Reduction feature which aids its use in urban environments.
A simple design with a single button on the telescope itself and a slotting mechanism with just two screws to hold it aloft the sturdy tripod makes this telescope one of the simplest we've ever reviewed (alongside the Unistellar eVscope 2 we reviewed). Users can get the telescope out of the box and ready to use in just a few minutes. The telescope can be synchronized with a smart device app (available on iOS and Android) via a quick pairing process. Once the telescope is paired with the app, users can manually slew the telescope and enhance exposure settings..
When the telescope is oriented, which it does automatically using the night sky and its on-board image sensor, the app allows us to automatically go-to night sky objects like galaxies, star clusters, nebulas and planets without any previous knowledge of the night sky or constellations.
- Read our full Unistellar eQuinox 2 telescope review
At approximately $2500/£2100, the Vaonis Vespera is the smallest and most reasonably priced smart telescope to date. This telescope from French startup Vaonis is a smaller, lighter version of its robotic older sister, the Vaonis Sellina which we reviewed recently.
Named after the Latin word for 'evening,' Vespera does not have an eyepiece like traditional telescopes but instead captures and shares images of the night sky with up to five connected smartphones or tablets through a mobile app called Singularity. The Vespera is effectively a camera for taking stunning pictures of deep sky objects, even in light-polluted cities. It is not intended for observing the moon and planets, but it can be used to capture remarkable images of star clusters, nebulae, and galaxies.
The Vespera is an impressive device that combines three technologies: star pattern recognition software, image live stacking technology, and an app. When switched on, its Sony IMX462 image sensor can detect a target in five minutes and take one photograph every 10 seconds (this varies depending on the target). This noise-canceling process can be seen in real-time on the Singularity app, resulting in a clearer, more contrasty and colorful image. In our Vaonis Vespera review, we found that the images were a little soft, but they could be enhanced with post-processing.
Additionally, it uses a planetarium to generate a 'tonight's best' list of celestial targets and an algorithm to determine the optimum camera settings for viewing each target.
The eVscope 2, a telescope designed with great finesse, is ideal for photographers who are new to astronomy and have a considerable amount of money (about $5000) to spare or for astronomers who desire an all-in-one system that is effortless to set up and use. Even though it may not be greatly appreciated by experienced telescope users accustomed to a more traditional viewing method, it can still create remarkable images.
The Unistellar eVscope 2 is a step away from traditional telescope stargazing and instead hosts an in-built camera, sleek design and electronic eyepiece. It is the second iteration of the eVscope line and has some noticeable improvements in both design and accessibility. It features a 4.5-inch (114mm) reflector with a focal ratio of f/3.9, which makes it ideal for viewing celestial objects such as nebulae.
Inside is a 7.7MP image sensor and new to the eVscope 2 is an electronic eyepiece designed by Nikon for those that want to get tactile with the telescope. The simple layout, stylish design, and excellent smartphone app user interface make the eVscope 2 a doddle to use and photograph the night sky with, especially with its enhanced tracking feature, which we were very impressed with in our Unistellar eVscope 2 review.
In reality, the product is only available to those with a substantial budget due to the high cost of its premium features.
- Read our full Unistellar eVscope 2 telescope review
Best telescopes to observe planets
Sitting at a price of less than $300, the Sky-Watcher Explorer 130 EQ2 is an excellent choice for those serious about taking the first steps into the world of astronomy.
Unlike other models at a similar price point, this telescope ships with an equatorial mount. When it is aligned with the Earth's axis, it makes it simple (after some practice) to follow objects in the sky once you've found them, as the Earth rotates.
It has a good-sized aperture at 5.1 inches, which means, unlike the models above, you will be able to explore deep sky objects, albeit only the brightest ones.
While not as long as the Celestron Inspire 100AZ, the Sky-Watcher Explorer 130 EQ2's long tube length results in f/7 and makes high magnification possible. During our review of the Sky-Watcher Explorer 130 EQ2, using the supplied Barlow lens, we could easily get sharp views of the Jovian System (Jupiter, its rings and moons) and Saturn's rings looked impressive.
This telescope is best suited for backyard stargazing, mainly due to its 12.6kg combined weight, which makes it a little more of an ordeal to take it out and about on sky-watching trips.
- Read our full Sky-Watcher Explorer 130 EQ2 review
The Orion Skyline 6-inch telescope is a great choice for beginner and intermediate astronomers alike due to its easy-to-use nature and high-quality optics.
This telescope offers an impressive 152mm objective lens which allows plenty of light to pass through and makes night sky targets more visible. The multi-coated optics further enhance the viewing experience, ensuring a clear image of those targets. With a focal length of 1200mm, you can observe the finer details of celestial bodies, such as craters on the moon and features of other planets.
This powerful telescope offers up to 133x magnification, allowing you to observe celestial objects in incredible detail. With the included eyepieces, this level of magnification is perfect for viewing the moon and planets. You won't miss out on any of the finer details.
It's also well built and easy to use, a huge plus for those without bags of astronomy experience. However, you can get alternatives for a lower price, but we've found they don't quite match the Skyline 6-inch for quality.
- See our guide of the best telescopes for viewing planets
The Celestron Omni XLT 102 is aimed at intermediate-level skywatchers, particularly those who have mastered setting circles and know how to use the right ascension and declination coordinates on the supplied high-quality CG-4 German equatorial mount.
The Omni XLT 102 features Celestron's StarBright XLT coating to maximize light transmission. The aspheric shaping technology in the Omni XLT 102 helps to reduce spherical aberration, a visual defect that causes incoming light to be concentrated at select points. This results in sharper and more detailed images that are more true to their natural color.
With its mix of aperture and f/10 focal ratio, this scope is able to produce excellent views of the planets, from Jupiter's atmospheric bands and moons, to Saturn's rings and the craters on the moon, showing great contrast between areas in shadow and those bathed in daylight. While there is a small amount of color fringing, views through the optical system are outstanding.
The refractor comes with a 25 mm eyepiece, 1.25-inch star diagonal, heavy-duty stainless steel tripod, accessory tray, spirit level, Starry Night Special Edition software and a 6x30 finderscope.
- See more of the Best telescopes for seeing planets
Best astrophotography telescopes
Celestron's EdgeHD technology turns Schmidt-Cassegrain telescopes into high-quality astrographs with perfectly flat fields. The way that the Schmidt-Cassegrain optics focus light usually means that the focal plane — where the light comes to focus — is curved, but if you are imaging, your CCD camera's sensor is flat. A curved focal plane on a flat CCD sensor results in field curvature, where stars at the edge of the field tend to blur. This is generally an unwanted effect for astrophotographers.
During our Celestron Advanced VX 8 EdgeHD review we were pleased to find that the optics in the EdgeHD negate the blurred edges, creating a perfectly flat field right to the edge of the frame for pinpoint sharpness across the whole image. The optical performance that the Celestron Advanced VX 8 EdgeHD delivers is impressive, with crisp and clear views with no optical distortion or false color.
As a bonus, the optical tube assembly comes packaged with Celestron's Advanced VX mount, which is tailor-made for imagers, capable of photographing across the meridian (an imaginary north-south line) without needing to do a meridian flip. The setup also performs periodic corrections to remove errors when tracking objects and also features an auto guider port.
The Celestron Advanced VX 8 EdgeHD can carry a load of up to 30 lbs. (13.6 kilograms) too, so the tube and all your imaging accessories are fully supported and stable. Also included are the standard NexStar+ hand controller, a 40 mm eyepiece, and access to Celestron's SkyPortal app and Starry Night Special Edition software. Check out our Celestron deals page to see if you can snap up a bargain.
- Read our full Celestron Advanced VX 8 EdgeHD review
Sky-Watcher's Skymax 150 is a great package for the price, with some models offering a high-quality equatorial mount for short-exposure astrophotography and long-exposure imaging. This well-constructed Maksutov-Cassegrain also comes with a single eyepiece with a focal length of 28 mm for a magnification of 64x.
The Skymax 150 weighs 13.23 lbs (6 kg), making it suitable for most regular equatorial mounts. Many makes and models of mounts will be able to support the weight of the telescope, as well as any extra accessories you may want to use, such as CCD or DSLR cameras, filter wheels, and other add-ons. For added versatility, the Skymax 150 comes with a Vixen-style dovetail plate, which can be attached to a variety of different mounts.
The Skymax 150's optical prowess is outstanding, with no sign of optical distortion. The telescope is a great all-arounder, suitable for imaging everything from the planets to deep-sky galaxies and nebulas — and as you would expect for a telescope designed for giving great images. As an added bonus, the instrument is a breeze to use and accessorize.
The focuser is lovely and smooth to operate and the Skymax 150 keeps a good amount of fine focus once it's been found — vital for long imaging sessions.
If this isn't the telescope for you, but you're after a Sky-Watcher scope, check out our Sky-Watcher deals hub to see if there is a model more suited to your requirements.
- Check out the Best cameras for astrophotography
Gemma is a contributing writer to Space.com, Live Science, science and space magazines How It Works and All About Space, history magazines All About History and History of War as well as Science, Technology, Engineering, Arts and Mathematics (STEAM) kids education brand Future Genius. She is the author of several books including 'Quantum Physics in Minutes', 'Haynes Owners' Workshop Manual to the Large Hadron Collider' and 'Haynes Owners' Workshop Manual to the Milky Way'. She holds a degree in physical sciences, a Master's in astrophysics and a PhD in computational astrophysics. She was elected as a fellow of the Royal Astronomical Society in 2011. Previously, she worked for Nature's journal, Scientific Reports, and created scientific industry reports for the Institute of Physics and the British Antarctic Survey.
How do I choose the right telescope?
Choosing the right telescope can be quite a challenge for the beginner. There has never been as much choice, so many optical configurations and range of prices than exist on today's market. In general terms telescope design and optical quality are usually pretty good nowadays — it wasn't always so. As buyers have become more informed via the internet and astronomical publications they have become far more discerning in their choice. This has meant that optical quality has improved and truly awful telescopes are, thankfully, becoming increasingly scarce.
Choosing a good all-round beginner's telescope capable of revealing 'the greatest show off Earth' depends on a number of things, including — in no particular order — your budget, your observing site, the telescope's portability, ease of use and setup, what objects, in particular, you would like to view, your ability to upgrade as your experience develops and whether you intend to attempt astrophotography through the telescope with a digital camera.
Regardless of a telescope's aperture or physical size, the most important thing to be aware of when purchasing any telescope is its optical quality. It is not advisable to buy a new telescope from any source other than a reputable telescope dealer. Most companies that make astronomical equipment their business are only too happy to help and advise by phone, email or during a personal visit to their commercial premises. Any reputable company that specializes in selling and/or manufacturing optical instruments will give by far the best deal, in terms of price, service and advice.
So if your biggest question is, 'which type of telescope type should I buy?' or 'what is the best telescope in the world?' let us help.
Telescope types compared
There are three primary types of telescopes: Reflector vs refractor vs catadioptric telescopes. Reflectors use a main mirror to gather and focus light; refractors use an objective lens, while catadioptrics use a main mirror and a lens of the same diameter. All three kinds of instruments have their own 'sub-species' based on their particular optical design. For example, the most basic type of reflector is the Newtonian design, which uses a main mirror and a small secondary mirror, which diverts the light at right angles to the eyepiece through the top end of the telescope.
Given a choice of quality, affordable telescopes, which one should you opt for? A Newtonian reflector on a simple undriven alt-azimuth mount (known as a 'Dobsonian') offers the best value in terms of aperture. Dobsonians are ideal if you want to learn your way thoroughly around the skies the 'old fashioned' way, with no bells or whistles, just a star map in hand. They collect lots of light and reveal those faint fuzzies, as well as having enough resolving power to deliver knockout views of the moon and bright planets. You will only practically be able to use a low to medium magnification on these instruments because anything higher than about 100x will shoot through the field before you've time to appreciate the view. Dobsonians over 6 inches in aperture are quite hefty, physically large and ideally need to be stored out of the way in the garage or garden shed.
Newtonians, as well as refractors, become a much more expensive prospect when an equatorial or computerized mount is added. Computerized mounts for Newtonians come in several forms — Dobsonian (push-to or GoTo), single tine-mounted (tracking or GoTo) and German equatorial (GoTo). A computerized push-to Dobsonian costs around twice as much as a manual one of the same aperture, while a GoTo costs around four times as much; a high-end Newtonian on a driven German equatorial mount may increase the cost more than tenfold!
If ease of use, portability and convenience are high on your requirements, and you like gadgets, then a short focal length refractor of up to 4-inches or catadioptric (Schmidt- or Maksutov-Cassegrain) up to 5-inches on a computerized mount may well fit the bill. Both types of instruments are versatile performers and will show a great many deep-sky objects as well as reveal considerable detail on the moon and planets at high magnification.
Achromatic refractors of short focal lengths typically display a degree of false color around the edges of bright objects like the moon because they can't focus all wavelengths of light to a precise point. Most users are happy to accept this drawback because refractors are so easy to use and take care of. In terms of delivering a clean, high-contrast view without false color, the Maksutov is the best option here.
The most exquisite views are to be had through apochromatic refractors. Using special glass objectives, they focus all wavelengths of light to as near a single point as possible and are free of false color. However, it is important to realize that apochromats cost around four times as much as equivalent-sized achromats.
How does a refractor telescope work?
Refractors work by bending — or refracting — the light that they gather to give you a view of your astronomical target. Easy to set up, the refractor is best suited to planetary and lunar viewing, making use of lenses to collect and focus light to form an image, while an eyepiece magnifies the view.
The refractor has a fairly straightforward design, with a main objective lens at one end and a star diagonal with a threaded eyepiece at the other. Being intuitive to use, the refractor is often a popular choice of instrument for novice astronomers given their low maintenance. Refractors are usually affixed to a simple alt-azimuth mount, that slews from side-to-side and up and down to locate a desired target. Being easy to use, means that these telescopes are also simple to manufacture (at least when it comes to the novice models) and therefore cheaper to buy.
The downside is that the higher the aperture, the more expensive the refractor gets. Unfortunately, this means that a basic refractor is also the number one target to replicate in mail-order catalogs and other non-reputable vendors so caution must be exercised when purchasing this type of telescope.
Refractors are particularly good at giving highly magnified and high contrast images and, because of this, are ideal instruments to use when looking at solar system targets such as the moon and the planets. The best refractors usually have an aperture of 2 inches (60mm) or more and will provide you with reasonable views of astronomical objects. If you're looking for a larger aperture, then a 3 to 4-inch (80 mm - 90 mm) would be best suited.
The drawback of a refractor is that it can suffer from chromatic aberration, also known as color fringing. When a single lens doesn't focus all of the colors emitted from a target object at the same point, bright objects such as the moon, Venus or Jupiter usually have a colored halo around them. To reduce this problem, many refractors are manufactured as achromatic or APOchromatic (also known as Extra Dispersion (ED) telescopes).
The achromatic refractor is cheaper than the apochromatic refractor and, combined with its efficiency, is often the type of telescope that novice astronomers go for. Even if you decide to go for the more expensive achromatic, you're still likely to get a stubborn degree of purple fringing around some targets.
Unless you're a seasoned skywatcher and you can afford to go for the more expensive apochromatic — which corrects for such an effect by using exotic glass for the lenses — this degree of color fringing will not ruin your observing experience to any great extent. If you do decide to go for the expensive option, then you will be stunned by the views you will get through these excellent telescopes. Be warned though, you might find that some apochromatics come without a tripod, something that you'll have to buy separately along with any accessories.
- Discover the Best tripods, Best travel tripods and Best camera accessories for astrophotography in our handy guides.
How does a reflector telescope work?
There are two common types of reflector telescope — the Newtonian and the Dobsonian. The way these instruments operate is exactly the same — they both use mirrors to reflect light to create an image of the object you're looking at.
The Newtonian telescope comprises a curved light-collecting mirror, which can be found at the tube's base. The light that hits this mirror is reflected back to the front of the tube, where a smaller flat mirror — oriented at 45-degrees — brings light to the observer who can see their chosen object.
The Newtonian can be found on alt-azimuth mounts, but you shouldn't be too surprised to find this type of reflector is more popularly affixed to an equatorial mount, allowing the telescope to follow the rotation of the sky while being aligned with your hemisphere's celestial pole. This reflector is a favorite in the amateur astronomy community due to its versatility in observing a wide selection of astronomical targets and allowing for astrophotography. With Newtonians, you can also buy a large aperture for less money — for instance, an eight-inch (203.2 mm) reflector would cost you less than a refractor with the same aperture, allowing you to get much more value for your money.
Newtonian reflector telescopes do require some maintenance. The mirrors must be aligned periodically to ensure that they are reflecting light properly. The mirrors can also become tarnished over time, so they may need to be repainted. If you choose a Newtonian reflector telescope, be sure to select one with a protective coating on the mirrors. This will help to extend the life of the mirrors and make them easier to maintain.
Some beginners to the hobby of astronomy might find setting up and using an equatorial mount tricky — that's where the Dobsonian comes in. These telescopes give the capabilities of a reflector without the complexities an equatorial mount will bring since it employs an alt-azimuth mount. Dobsonians are very simple to use and can easily be pulled into orientation when looking at astronomical objects. If you're not confident in navigating your telescope though, then GoTo or computerized Dobsonians and Newtonians (that slew to objects for you using an in-built motor) are on the market — but cost more. Learn more about these in our 'What are Dobsonian telescopes' guide.
Whatever reflector you choose, these telescopes are excellent for low-magnification targets such as galaxies and many types of nebulas.
How does a catadioptric telescope work?
Ideal for astrophotography, the catadioptric is an excellent instrument for taking a wide range of astronomical targets and is manufactured in order to take the best parts of two kinds of telescopes: The reflector and the refractor. What's more, the catadioptric takes advantage of a lightweight design, meaning that it's much more portable than other kinds of telescopes and its sealed optics promote little to no maintenance. The only major downside to choosing a catadioptric is that the vast majority can be expensive. However, if you are on a strict budget, picking up one of these instruments isn't unheard of — you've just got to make sure to shop around.
While refractors use lenses, and reflectors make use of mirrors, to create and magnify an image, the catadioptric makes use of both lenses and mirrors for high-definition and superior views. During your observations, light from your chosen target passes through to a lens, which corrects or reduces aberration that distorts the view that is later taken in through the eyepiece. Curved primary mirrors then reflect this light onto a secondary mirror, which then reaches your eyes. You will find two kinds of Catadioptric telescopes — the Schmidt-Cassegrain and the Maksutov-Cassegrain.
The Maksutov-Cassegrain, also affectionately known as the 'Mak', corrects the optical problem that is experienced by reflectors — an aberration effect called 'coma,' which can make objects look distorted and appear like they have a tail. This effect is reduced or banished with the combined efforts of a spherical mirror and a meniscus lens, the latter of which is 'weakly negative'. The Maksutov is also adept at correcting for chromatic aberration, or color fringing, a distortion that creates an unwanted purple or blue edging around bright night-sky objects.
Packed into its short optical tube is a system that allows you to target higher magnification objects such as the planets, moon and double stars. Additionally, if you struggle to find objects and your way around the night sky, then both this type of catadioptric telescope and the Schmidt-Cassegrain can be found in abundance and equipped with a GoTo system.
The other most common kind of catadioptric, the Schmidt-Cassegrain, offers similar capabilities to the Maksutov and will allow you to make general observations of planetary targets and stars. It is also possible to expand the telescope's field of view with the help of corrector lenses, enabling exquisite views of an even wider selection of astronomical targets.
What is a finderscope?
A finder scope is a low-power (low magnification) telescope that sits on your main telescope. Your main telescope will typically have a narrow field of view, meaning you'll see only a little portion of the sky when you look through it. Your finder scope, with a wider field of view, assists you in pointing your telescope to your desired subject, making it easy to hone in on your target with minimal searching and repositioning.
Center your subject in the finder scope's frame; there are usually crosshairs or a dot so you know when it's central. Now when you look through your telescope's eyepiece, your subject will be centered here too.
Many telescopes include a finder scope with the package but if you need to purchase one separately it's worth knowing there are two main types. One has a straight-through view, and one has a right-angled view. Generally, you'd want a right-angle finder if you have a Newtonian reflector telescope and a straight-through view if you use a refractor or catadioptric due to the location of their eyepieces. Some finder scopes will also be magnified — higher magnification and a narrower field may be desirable if you need pinpoint accuracy.
You'll also come across the terms 'inverted' or 'erect image.' The latter means the finder scope has a correcting prism that flips the image the 'right way up’ (top-to-bottom) and ‘around’ (left-to-right). Some finder scopes don't have a correcting prism, so you see either a back-to-front image or upside down, which might be disorientating and make finding subjects more difficult, especially if you're just starting out.
What does aperture, magnification and focal length mean?
Time to dispel jargon myths with a bit of a telescope glossary. The larger a telescope's aperture (the size of its main lens or primary mirror) the more light is collected and more fine detail is revealed. For example, a 200 mm aperture collects four times more light than a 100 mm telescope. Under ideal conditions, a 100 mm telescope reveals stars down to magnitude +11.8, while a 200 mm telescope will show stars down to magnitude +13.3. A 100 mm telescope will 'split' a double star separated by 1.5 arcseconds and resolves a three-kilometer lunar crater; however, a 200 mm telescope resolves a crater just 1.5 km across and a double star separated by just 0.6 arcseconds. Resolution is limited by the telescope's optical quality and the steadiness of the Earth's atmosphere.
Telescopic magnification depends on the telescope's focal length (the distance between the objective lens/primary mirror and the point of focus of the light it collects) and the focal length of the eyepiece used. Magnification is calculated by dividing the telescope's focal length by the eyepiece's focal length. For example, a 100 mm telescope with a focal length of f/8 (eight times the telescope's aperture) has a focal length of 800 mm; used in conjunction with an eyepiece of 10 mm it will deliver a magnification of 80 times (800 divided by 10).
With any telescope, the range of useful magnification depends on a telescope's aperture and focal length, combined with the focal length of the eyepiece. Too low a magnification (taking in as wide an area as possible) will actually waste light since the 'exit pupil' of the eyepiece will be larger than the diameter of the pupil of your dark-adapted eye. On average, the adult pupil will dilate to around 7 mm in dark conditions. Therefore the exit pupil delivered by an eyepiece ideally needs to be 7 mm or smaller so that all the light gathered by the telescope — especially when attempting to see faint objects — can be taken in. Exit pupil can be calculated by dividing the telescope's aperture by the magnification delivered by any particular eyepiece.
Magnification: How do eyepieces work?
Eyepieces work by magnifying the light focused by the telescope's primary mirror or objective lens. Every telescope eyepiece has a specific focal length (given in millimeters), and the shorter this figure is, the higher the magnification. To calculate the magnification provided by any particular eyepiece on any telescope, divide the telescope's focal length by the focal length of the eyepiece used. For example, a 1000 mm focal length telescope (say, a 100 mm refractor of f/10, or a 200 mm Newtonian of f/5) will deliver a magnification of 100 with a 10 mm eyepiece (1000 divided by 10 = 100).
Although any telescope can give impressively high magnifications using short focal length eyepieces, there is a point when increasing magnification will provide a worse image rather than improve it. When an object is magnified, its brightness is reduced as the finite amount of light is spread over a larger area. In addition, increasing magnification exacerbates the amount of atmospheric turbulence visible; therefore, high magnifications can only be used when seeing conditions are good. Finally, high magnification is practical only with driven telescopes. Otherwise, the object will quickly drift out of the field of view.
As a guide, your highest power eyepiece should deliver a magnification double the telescope's aperture in millimeters — for example, 200x on a 100 mm telescope, 400x on a 200 mm telescope, and so on.
It's best to have at least three good quality eyepieces that deliver low, medium and high magnifications — say around 50x, 100x and 200x. Taking as an example a 100 mm f/10 telescope, those eyepieces would be of 20 mm, 10 mm and 5 mm focal length. Let's assume that these particular eyepieces are of the commonly used Plossl variety. A field of view around one degree across (an area of 0.8 square degrees) is given by the 20 mm eyepiece — ideal for sweeping the deep skies and finding objects. The 10 mm eyepiece will just take in the half-degree diameter moon and have a field covering just one-quarter that of the 20 mm eyepiece. With its high magnification, the 5 mm eyepiece has a field of view covering just one-sixteenth that of the 20 mm eyepiece and can only be used when seeing conditions allow.
How we test the best telescopes
To guarantee you're getting honest, up-to-date recommendations on the best telescopes to buy here at Space.com we make sure to put every telescope through a rigorous review to fully test each instrument. Each telescope is reviewed based on numerous aspects, from its construction and design, to how well it functions as an optical instrument and its performance in the field.
Our expert staff and knowledgeable freelance contributors thoroughly test each telescope. This ensures honest reviewing based on the telescope's price, category, and intended use. For example, a 10-inch Dobsonian should not be compared to a 2.76-inch refractor, even though they may be the best in their own class.
We assess the ease of setup of both computerized and motorized mounts, as well as their reliability, accuracy, and noise level. Additionally, we decipher whether a telescope comes with appropriate eyepieces and tripods. We also make suggestions for any additional kits that may be beneficial for the best experience possible.
With complete editorial independence, Space.com are here to ensure you get the best buying advice on telescopes, whether you should purchase an instrument or not, making our buying guides and reviews reliable and transparent.
Aside from this comprehensive list, we do also have brand-specific telescope guides for Celestron, Skywatcher, Meade, and Orion deals for those loyal to their favorite brands. Like this guide, we also keep those updated year-round, so they're always worth checking out. There are plenty of stores out there that dabble in skywatching equipment as well. Do Best Buy sell telescopes? They sure do, and we have a guide on Telescopes at Best Buy.
Still wondering 'what telescope should I buy'? We have also selected our favorite budget telescopes under $500, best beginner telescopes and best telescopes for kids and not just what the best telescope to buy for adults is, in case you're looking for those specifically.