What type of Telescope do I need?
This is the really the most important question regarding all things astronomy – what type of telescope works best and gives me the most ability to peer into the heavens?
- Do I want the biggest magnification factor?
- Do I want a brighter image?
- Do I want that ultra long focal length?
- What works best for me?
It really has been the same conundrum for the early inventors and the aspiring astronomers throughout time as this question can only be answered by tracing the evolution of the telescope and the exploration of the stars since the earliest times.
There really are a diverse range of equipment, options and models and accessories to choose from and although astronomy can be expensive, a few well made decisions can offer you a wealth of viewing pleasure without costing all of your financial wealth.
First some words of advice! Practice first by learning to spot the obvious planets, stars, and maybe a constellation or other feature with the naked eye. If you can’t find the easy targets, it will be much more difficult to locate things with a telescope which can be entirely like fumbling around in the dark (no pun intended!), How else would you expect to find things with a telescope – trial and error is not the best approach! Needless to say you should spend some time researching the subject in order to become familiar with the subject of astronomy. Not only the skies, you will also need to become familiar with the variety of equipment, the types of devices as well as the names of the instruments, so that you can be ready to make an informed decision.
Lastly, look for a hobby group of amateur astronomers with a similar interest as yourself, and ask to share their experiences, trials, mistakes and successes, Far better to learn from someone else’s mistakes than to spend your money unwisely. In addition to checking out the viewing potential of various models and aperture dimensions of someone else’s telescope, you will very quickly discover the benefits of size versus portability versus reflector versus refractor or whatever.
Different types of Telescopes
If you are interested to read further about the evolution of the telescope, then feel free to spend some time reading about how the different types of telescopes were designed and invented over the ages, and especially some of the famous names that we have come to associate with the design of the modern telescope.
Otherwise, let’s get straight to the point – amateur
telescopes are basically available in three different designs:
Refractor Telescopes
The refractor telescope is probably the most basic type of telescope design. Refracting telescopes take in light through the objective lens at the front and focus the light beams to the eyepiece at the other end. Refracting telescopes are thought to be the first type of telescopes to be invented in Europe in the early days of astronomy, but became obsolete due to newer inventions by Newton and other inventors. However, more modern technology to produce glass lenses and even the development of newer and better materials have made the refractor telescope a popular choice for modern amateur astronomers.
What are some of the advantages of using a Refractor telescope? As a beginner, it is important to note that refractor telescopes offer the best images and therefore provide the best bang for buck for the amateur astronomer. This is due to the basic optical layout of the design of refractor telescopes, which have no obstructions of the light path and hence in theory can provide a clearer image.
What are some of the disadvantages of using a Refractor telescope? Look out for color aberrations in this type of telescope which can be a bit of a nuisance even in expensive telescopes. This type of telescope can become very large in size for large aperture instruments, so you have to be able to manage a large telescope if you want the best viewing capability. This also comes with a hefty price tag, and as a general rule, these refractor telescopes will tend to be the most expensive.
A typical 4″ refractor
Reflector Telescopes
The next type of telescope that we will discuss are called Newtonian Reflectors because they were designed by Isaac Newton. This telescope is basically designed around a parabolic mirrored lens which reflects the image back to the front of the tube to a conveniently mounted eyepiece.
What are some of the advantages of using a Reflector Telescope? Generally the reflector telescopes are the smallest of the different types of telescopes, despite having a similar sized aperture to its larger cousins. This helps keep costs down and makes these the most economic of the three different types of telescopes, and also helps to keep the size and weight to a minimum, and generally smaller than refracting telescopes.
What are the disadvantages of the Reflector telescopes? Be aware that secondary optical effects can sometimes cause a loss of clarity in a reflector, and these types of telescope can require attention to repair the collimation or alignment of optical components. Small hint at this point – keep your instrument tuned for optimal performance!
An 8″ Newtonian Reflector
Cassegrain Telescopes (including derivatives)
The Cassegrain types of telescopes are basically a type of hybrid design which use both mirrored reflectors and optical lenses to focus the optical path inside the telescope, which results in a shorter, more compact telescope tube. The obvious benefit here is to keep the focal length as short as possible, while still maintaining a wide aperture to focus as much light as possible, and to gather as bright an image as possible. The Cassegrain telescope has many different sub types and its derivatives are named after the various inventors, such as the Maksutov-Cassegrain telescope, the Schmidt-Cassegrain or the Schmidt-Newtonian. Each of these sub types of telescopes have their own characteristics, and their own range of fans who will choose a particular type of telescope no matter what the other benefits may have to offer. These parochial fans will also give a name for the pet favorites, and the most common type of Cassegrain telescope is known as the “Schmidt Cassegrain Telescope” which for convenience has become known as the SCT.
What are some of the advantages of using a Schmidt-Cassegrain Telescopes? The Schmidt-Cassegrain Telescopes are the smallest of the three types of telescopes, and therefore generally cheaper than refractor telescopes. However you can buy many types of accessories for these telescopes, and a good example is that these designs can be totally computerised, which is a huge bonus or your viewing pleasure. Of course there is a cost for these additional features, but if you know about these facts up front you can factor this into your decision process. Additionally, these Schmidt-Cassegrain types of telescopes tend to be the most popular.
What are some of the disadvantages of the Schmidt-Cassegrain Telescopes? The SCT can tend to cost more than reflecting telescopes, and you have to be aware that the images can be inferior to the other telescopes, but this is subject to much debate, and can be rectified by buying more of the accessories that I mentioned above!
a Maksutov-Cassegrain by Meade
