Telescope buyer's guide
Choosing a telescope
Our telescope buying guide will help you to choose the best telescope for you. If you’re interested in astronomy and want to purchase your first telescope but just don’t know where to start, or maybe you are overcome by the technical jargon and the huge variety of options available, then our buyers guide will provide you with all of the information that you need.
The information below will guide you through the decision making process, exploring the differences between telescopes and other scopes such as binoculars, and helping you understand the technical differences between different types of telescopes. We’ll help you choose the perfect scope to suit your needs.
Is a telescope the right option for me?
When deciding on the best scope for you, it is important to consider what you wish to view through it. Telescopes, binoculars and spotting scopes are all designed to be used in different environments and can’t often be used interchangeably, so it’s important to think which environment you are most keen to focus on. Take a look at the comparison below to help guide your decision making.
Telescope vs binoculars vs spotting scopes
Telescopes – Telescopes are primarily designed for night viewing. They have unique optics and light gathering capabilities that allow the viewing of objects in complete darkness, however lack the ability to properly view objects during daytime. Some telescopes can be used for viewing both the sky at night and also land views, however they flip images from left to right, distorting the actual view and producing a mirror image of it. Although it is possible to use these Refractor telescopes for terrestrial viewing, they are best suited for astronomy, so if you're mainly interested in land viewing then a telescope may not be for you. If you’re main focus in astronomy then a telescope is probably the best option for you.
Spotting scopes - If you're mainly planning on using your scope for getting a closer view of the ocean, or the beautiful countryside that surrounds your home, then a spotting scope may be the best option for you. Spotting scopes are basically telescopes that are especially designed for land viewing. Their primary role is to magnify the image that you see through them, and they do this without distorting the true image. Spotting scopes have a large front lens, and often have a zoom magnification that allows you to zoom between a lower and higher magnification if you spot something of interest and want to get a closer view of it. This is not as easy with a telescope, as you have to change eye pieces to alter the magnification. Some spotting scopes with larger lenses are also appropriate for occasional astronomy but we wouldn't recommend purchasing a spotting scope if that's going to be your primary activity.
Binoculars – Some types of binoculars are designed for both day and night viewing, making them the perfect option for people who would like a scope that can be used in both environments, for both activities, and are nice and portable. Some astronomy enthusiasts actually favour binoculars over telescopes as they are lighter, easier to move around, and provide a wider field of view than telescopes. Despite giving a lower magnification than telescopes, binoculars will allow viewers to see much more detail in the night sky than the naked eye. Often the number of stars visible on a clear night will double with the aid of even a basic pair of binoculars; however most of the more interesting astronomical objects will appear very faint through them.
If you want to use binoculars for astronomy, then it is important to choose a good pair of full-sized binoculars that are designed to capture as much light as possible. Find out more about choosing the best binoculars for you in our binoculars buying guide.
Choosing the right telescope for you
If you have decided that a telescope is for you, then it’s time to take a closer look at the specification and type of telescope that you require.
Telescopes are designed to do two things: to brighten and magnify your views of astronomical objects. Due to this, it is important to consider a telescopes aperture and magnification.
The most important feature of any telescope is its aperture. The aperture of a telescope refers to the diameter of its main optical component. This can either be a lens or mirror depending on the type of telescope (we will look more closely at different types of telescopes later). The larger the aperture, the more light that can come into the telescope, and the brighter and clearer your image of astronomical objects will be. Sometimes the aperture of a telescope is known as its objective lens diameter.
NOTE: Although a large aperture will result in a brighter and better image it will also mean that your telescope will be larger and heavier. When deciding on the best aperture to suit your needs, take some time to think where you will be using your telescope. Effective astronomy requires viewing from a dark location which is not always available in urban areas. If you need to travel to use your telescope then you will need to consider how portable it is and consider choosing a telescope that has a lower aperture but it much easier to move around and setup.
Unlike other scopes, the magnification of a telescope is not a high priority; aperture should always be your main consideration. Regardless of a telescopes magnification power, if its aperture is low, then your image will be very dark and no amount of magnification will make it any clearer.
Using a high magnification telescope will also affect how much of the night sky that you can actually see, as you are effectively zooming in on a very small area.
NOTE: the magnification of a telescope can be increased or decreased by switching eye pieces, so it’s best to choose a model that has a high aperture and then make adaptations to the magnification using eye pieces if you wish. Many telescopes come with a few eyepieces and some come with a Barlow lens which doubles the magnification of any eye piece that it is connected to.
What type of telescope should I choose?
There are 3 basic types of telescopes: Refractor, Reflector and Cassegrain. All three types of telescopes are designed to brighten and magnify your views of celestial objects; however they each do this in a different way. A Refractor telescope uses lenses, a Reflector uses mirrors and a Cassegrain uses both.
Refractor telescopes are the most common type of telescopes. Refractor telescopes consist of a long tube with a large lens at one end and an eyepiece at the other.
- Simple design which is easy to use
- Good for distant terrestrial viewing and lunar, planetary and binary stargazing
- Sealed tube protects optics
- Little or no maintenance needed
- Generally have small apertures so wont draw in as much light as other models
- Less suited for viewing small and faint deep sky objects such as distant galaxies
- Heavier, longer and bulkier than reflector and catadioptric telescopes with equivalent apertures making them less practical to transport
- Good-quality refractors cost more per inch of aperture than any other kind of telescope.
- Can be used for terrestrial viewing, but images will be slightly distorted, as they flip images from left to right, distorting the actual view and producing a mirror image of it.
Reflector telescopes use two mirrors instead of a lens to gather and focus light. Reflector telescopes are similar in look to refractor telescopes, but have an eyepiece on the side of the tube for viewing. There's a range of reflector telescope designs, often named after the person who invented them, including Newtonian, Gregorian, and Cassegrain Reflector telescopes. Although each design varies slightly, all use mirrors in their design. Dobsonian telescopes are a type of Newtonian reflector telescope and they're often the biggest reflector telescopes on the market
- Easy to use
- Have large apertures which deliver bright images and make them excellent for viewing faint deep sky objects such as remote galaxies and star clusters.
- Low in optical irregularities
- Quite compact and portable
- Reflector telescopes cost the least per inch of aperture compared to refractors and catadioptrics as mirrors are cheaper to produce than lenses.
- The tube is open to the air, which means that dust can gather on the optics
- May require more care and maintenance
Catadioptric telescopes use a combination of mirrors and lenses. These telescopes are modern in design and are a popular choice. They’re often used with battery-operated computerized mounts, which help users to find celestial objects. There are two popular designs of Catadioptric telescopes, the Schmidt-Cassegrain and the Maksutov-Cassegrain.
In Schmidt-Cassegrain telescopes, the light enters through a thin, aspheric Schmidt correcting plate, hits the spherical primary mirror and is then reflected back up the tube, where it is intercepted by a small, secondary mirror. This secondary mirror then reflects the light out of an opening in the rear of the instrument to form an image at the eyepiece for you to see.
- Best near focus capability of any type telescope
- Good for deep sky observing or astrophotography
- Excellent for lunar, planetary and binary star observing
- Can be used for terrestrial viewing and photography
- Closed tube design reduces image degrading air currents
- Compact and durable
- Great all-purpose telescope design which combines the optical advantages of both lenses and mirrors and cancels out their disadvantages.
- Excellent optics with razor sharp images over a wide field of view
- Easy to use
- Durable and virtually maintenance-free
- Offer large apertures at reasonable prices less expensive than equivalent-aperture refractor designs
- Lots of accessories can be added
- More expensive than reflectors of equal aperture
- Looks different to the usual idea of what a telescope should look like
- Secondary mirror causes a slight loss of light and reduces image brightness
Maksutov-Cassegrain telescopes are also catadioptric in design and similar to Schmidt-Cassegrain telescopes, use both mirrors and lenses.
The two types of telescope differ slightly, as the Maksutov-Cassegrain uses a thick meniscus-correcting lens with a strong curvature and its secondary mirror is usually an aluminised spot on the corrector meaning that it is typically smaller than the one included in Schmidt-Cassegrain telescopes.
The advantages and disadvantages of Maksutov-Cassegrain are similar to those of the Schmidt-Cassegrain, but there are a number of differences between the two.
- As the Maksutov-Cassegrain telescope’s secondary mirror is smaller than the Schmidt’s, it produces a slightly better resolution for planetary observing.
- The Maksutov is heavier than the Schmidt and, because of the thick correcting lens, takes a long time to reach thermal stability at night in larger apertures.
- The Maksutov optical design typically is easier to make, but its corrector lens requires more material than the Schmidt Cassegrain’s.
Comfort and Stability
Don’t forget, that comfort and stability are important factors when choosing a telescope. If you are going to be using a telescope for an extended period of time, then you will want to ensure that you are in the best position to enjoy the objects that you are viewing, so that you can truely enjoy the experience.
When choosing your telescope be sure to find out what type of mount it uses. Generally there are two types of telescope mounts, altazimuth or alt-azimuth (AZ) mounts, and equatorial (EQ) mounts.
AZ mounts allow for manual adjustments to the telescope, and you basically use the mount adjustments to pull the telescope left and right and up and down to view and track moving celestial objects such as stars and planets.
EQ mounts on the other hand are often considered easier to use once they're set up, as they have a slow motion control that moves the telescope in an arc across the night sky (the direction that stars etc naturally move in due to the rotation of the earth) making it easier to keep track of objects you're following. The inclusion or exclusion of an EQ mount can significantly effect the price of a telescope regardless of the aperture and focal length that the telescope may have.
Don't forget that you'll need a tripod for your telescope to ensure optimal comfort and clarity. Tripods can vary across telescope model, being made of different materials and some including a stabilization feature. Most of our telescopes come with a tripod but some will need a tripod to be purchased separately so please ensure that you read the specifications of any telescopes of interest carefully so you know exactly what you're getting.
Now that you have found out more about magnification, aperture and the different types of telescopes, you can browse our telescope collection informed. The choice of what telescope to buy is totally up to you and you should choose the best telescope for your individual circumstances and needs. If you have additional questions that have not been answered here, then why not check out our telescope FAQ's for more information, or contact us anytime.
Want to find out more about each type of telescope mentioned above? Why not checkout one of the fantastic books below?
Keeping it simple:The Totally Non-Geeky Guide to Choosing and Using Telescopes (The Totally Non-Geeky Guides Book 1)
The No-Bull Guide to Choosing Your First Telescope
Technical guides:Choosing and Using a Refracting Telescope (The Patrick Moore Practical Astronomy Series)
Choosing and Using a Dobsonian Telescope (The Patrick Moore Practical Astronomy Series)