There are three main types of telescopes to choose from:
Each of these function in its own way and has its advantages and disadvantages. I’ve explained the main differences between these types of telescopes below. It’s a matter of you reading the facts and deciding which of these are important to you and your specific needs.
If there are any terms you are unfamiliar with, please refer to my glossary for an explanation.
A refracting telescope is the simplest type of telescope and probably the most recognizable. It’s design is so simple, that it is essentially a tube with a lens at each end.
How Refracting Telescopes Work
If you are wondering how refracting telescopes work, it is actually very simple.
(1) Light enters through a main objective lens at one end.
(2) The lens refracts (bends) the light to a point of focus at the other end.
(3) This is then magnified to form an image by the eyepiece which is inserted in the other end of the telescope. The eyepiece can be moved back and forth to adjust the sharpness of the focus.
Advantages of Refracting Telescopes
Because of their simple design, they are generally easy to use and more reliable as their optics are permanently fixed and aligned.
Disadvantages of Refracting Telescopes
They can be heavy, especially larger aperture telescopes, because of their need for large lenses. They can also have a longer body which may impact on transportation and storage.
They may also be more expensive, as large high quality lenses are more costly to produce. Cheaper lenses are more susceptible to aberrations.
A reflecting telescope is similar to a refracting telescope, but just a little bit more complex. It is called a reflecting telescope because it uses mirrors to reflect the light internally.
How Reflecting Telescopes Work
As previously mentioned, the way a reflecting telescope works, is similar to how refracting telescopes work.
(1) Light enters at one end.
(3) This mirror reflects the light into an eyepiece, which is usually mounted on the side of the telescope (4). The eyepiece can be adjusted to alter the sharpness of focus.
Advantages of Reflector Telescopes
This style of telescope is fairly compact and portable which is great for transportation and storage. They are also generally more affordable (particularly as mirrors are cheaper to produce than lenses).
Typically, mirrors can produce less optical aberrations than lenses.
Disadvantages of Reflector Telescopes
The mirrors may need regular re-alignment as they can easily slip out of alignment due to knocks and bumps or even temperature changes.
In some instances, they can be susceptible to spherical aberrations which can interfere with image quality.
The Catadioptric could be considered a hybrid refracting/reflecting telescope, in that it uses both mirrors and lenses to form the image.
How Catadioptric Telescopes Work
How a catadioptric telescope works is rather quite interesting.
(1) Light enters at one end through a correcting lens, which helps reduce aberrations.
Advantages of Catadioptric Telescopes
Most catadioptrics are extremely compact and portable, which makes them easy to transport and store.
The optics provide the advantages of both lenses and mirrors, so they make a great all purpose telescope.
Disadvantages of Catadioptric Telescopes
They may suffer a slight loss of light because the positioning of the secondary mirror places it in the middle of the main opening.
Take The Next Step
If you are ready to begin star gazing, Amazon has a wide range of telescopes to suit all skill levels and budgets. You will find a selection of those currently available, listed below.