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Apr 10

A Quick Guide To The Different Types of Telescopes You Can Buy

Most people have a very stereotypical view of telescopes in terms of what they look like and what they’re capable of in the first place. The way telescopes have been marketed over the years is part of this problem, and this is doubly true of the trashscope market. If your only experience of astronomy has been through a cheap mail-order telescope then you’re missing out on everything that more advanced and reliable telescopes can offer you.

Refractor TelescopeRefractor Telescopes

This is the most common type of telescope you’ll find retailing both online and offline, and can also be some of the cheapest you’ll find too. A lens is used to focus the light from distant celestial objects into the eyepiece on these telescopes; which is always located at the far end of the optical tube itself. One of the many reasons refractor telescopes are popular is because the optical tube is sealed so there’s a dramatic reduction in diffraction caused by looking through air, which can vary in temperature so much. Since there are almost no moving parts in a refractor telescope it also makes them almost entirely maintenance free, making them very popular with amateur astronomers. Refracting telescopes can be used both during the night and during the day too.

Reflector TelescopeReflector Telescopes

A reflector telescope is often referred to as a Newtonian telescope, named after the British physicist who invented it. The basic design of any reflecting telescope is to use one or more mirrors to focus light from stars and planets into an eyepiece. What’s very different about this method of stargazing is that the eyepiece itself is located at the top of the telescope and at a 90-degree angle. The reason for this is the mirror which collects the light is located at the base of the telescope and the secondary focusing mirror is located at the front so the only possible viewing angle is from the side. The major benefit of a reflecting telescope is that they have massive amounts of light grasp thanks to their large aperture, so no matter how faint or distant a star or planet is this type of telescope can produce surprisingly clear images. Reflector telescopes are more complex than refractors, so do require a small amount of maintenance from time to time and they’re also not suitable for use during the day.

Catadioptric TelescopeCatadioptric Telescope

There’s a whole heap of names for this type of telescope and you might also hear people call it a Maksutov-Cassegrain, Schmidt-Cassegrain and lastly a compound telescope. What a compound telescope offers you is the light gathering capabilities of a reflector telescope combined with the ease of use which comes with refractor telescopes. They also tend to be physically smaller than either reflectors or refractors, so are far more suitable for use as a desktop telescope for example. Due to their design a catadiopter doesn’t require as much maintenance as a reflecting telescope and can also be used during the day.

Dobsonian TelescopeDobsonian Telescopes 

We felt it was important to include this type of telescope here simply because it’s unique to refractors, reflectors and compound telescopes in one very simple way – the mount. The other types of telescopes we’ve mentioned here all use an equatorial, Altazimuth or similar type of mount. A Dobsonian telescope is when you take a standard Newtonian/reflector telescope and mount it on a Lazy Susan-type of base which also allows the telescope to tilt forwards and backwards. The only downside to this type of telescope is that because the Dobsonian mount is so versatile they’re often used to mount extremely large Newtonians, which doesn’t make them very portable. Also because they’re a reflecting telescope you won’t be able to use them during the day to gaze at local mountains or other stuff near you.

Computerized TelescopesComputerized Telescopes

Again this isn’t really a type of telescope in its own right but because they’re very popular with astronomers of all ages we figured we’d better include them. A computerized telescope is usually either a small reflecting or compound telescope, with an aperture of around 8-inches mounted on a single or double-fork mount. The motion of this type of telescope is then controlled with a small handheld computer which is usually pre-programmed with somewhere between 10,000 and 40,000 planets, stars, moons and Messier Objects. What’s really neat is that instead of you trying to figure out what you’re staring at with a printed star chart you just push a few buttons and your telescope will align you with whatever you want to spend the next few hours gazing at.

A Final Word

Which type of telescope is best for you? That’s all going to depend on your experience, your budget and even on how portable you want your telescope to be. Most astronomers with a budget over say $250 will tend towards a basic 6-inch reflector, but after that it’s down to how much cash and space you have for your new telescope in the first place.

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