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If you are looking to buy your first telescope, you will find out that there are a few types of telescope designs. The main telescope designs you can choose from are the refractor telescope and reflector telescope.
Many people buying the first telescope are making the decision based on the look of the telescope. That is a huge mistake because there are big differences between refracting and reflecting telescopes.
The main difference between refractor and reflector telescope is that the refractor uses optical lenses, and the reflector telescope uses mirrors. The difference is also in the maintenance required between those two. The refractor telescope requires less maintenance than a reflector telescope. Refractor telescopes usually have smaller apertures and are more expensive than reflector telescopes.
There are also other telescope designs like Schmidt Cassegrain and Maksutov Cassegrain telescope, but in this article, I will only talk about Refractor vs. Reflector telescopes.
If you want to learn more about the other designs, you can read my article Schmidt Cassegrain vs. Maksutov Cassegrain.
How Does Refractor Telescope Work
Refracting telescopes are very common telescopes used by amateur astronomers. These telescopes are using only lenses to magnify the distant object. Modern refracting telescopes are using Keplerian Refractor design.
The Keplerian Refracting telescope uses a convex lens at the front and a convex lens inside the eyepiece at the back of the telescope behind the primary lens’s focus point. The light is refracted in the primary lens and produces a magnifying image in the eyepiece, hence called “Refracting” telescope.
Because the eyepiece is situated behind the primary lens’s focal plane, the eyepiece’s image is inverted both vertically and horizontally. This design allows for a more significant apparent field of view in the eyepiece and a longer focal length telescope to achieve higher magnification.
Galilean Refractor design is using a convex lens and concave lens in the eyepiece, but the eyepiece is placed before the focus point of the primary lens. This design is producing a true image that is not inverted. Galilean Refractor design is more like a spying glass, and it is not used in the modern refracting telescopes.
How Does Reflector Telescope Work
The reflecting telescope is also called the Newtonian telescope because it uses the Newtonian design. This design uses mirrors to produce an image. The only lens in the reflecting telescope is the eyepiece.
Reflecting telescope uses a spherical or parabolic primary mirror at the end of the telescope tube. The tube is open, the light goes through and reflects from the primary mirror to a small flat secondary mirror at the front of the telescope.
The secondary mirror is tilted 45 degrees and reflects the light into the eyepiece on the side of the tube. Mirrors reflect the light to create an image in the eyepiece; that’s why it is called a reflecting telescope.
Refractor Telescope Advantages
- Refracting telescopes are easy to use and require little to no maintenance.
- They are usually small and compact.
- Refracting telescope is a good choice for kids.
- Refractors with complex lens designs are the number one choice for astrophotography.
- Temperature change doesn’t affect the stargazing experience because of the closed tube design.
- A Refracting telescope is an excellent choice to observe the moon and planets.
Refractor Telescope Disadvantages
- Refracting telescopes are available only with small apertures.
- Chromatic Aberration – “color fringing” is a problem with the lenses where they can’t focus all colors to a one-point. A compound lens is correcting this issue resulting in a higher price of the telescope.
- High-quality refractors with compound lenses are very expensive.
- Because of the small aperture, they can’t collect enough light to enjoy observing deep-sky objects like nebulae and galaxies.
Reflector Telescope Advantages
- Reflecting telescopes are available in gig apertures.
- The mirror is easier to manufacture than a lens, so they are cheaper than refractors.
- Big mirrors can collect a lot of light to enjoy every object in the night sky.
- Reflecting telescopes have no Chromatic Aberration.
- Even big observatory telescopes and space telescopes are using mirrors.
- A reflecting telescope is the best telescope for the money.
Reflector Telescope Disadvantages
- Reflecting telescope needs more maintenance than refracting telescope.
- Mirrors need to be aligned to get the best image. This is called Collimation, and it needs to be done on every reflecting telescope from time to time.
- Because of the open tube design, the sudden temperature change can affect the image quality.
- Reflecting telescopes with big apertures are hard to transport and store.
- Comatic Aberration – the stars can be elongated around the edges of the field of view. The problem can be corrected by a coma corrector, adding to the price of a telescope.
Refractor vs. Reflector Telescope In Visual Astronomy
Comparing the refracting and reflecting telescope for use in visual astronomy is subjective. Some amateur astronomers prefer the views through the refractor and others through the reflector.
In my opinion, the clear winner for visual astronomy is the reflecting telescope. In astronomy, we need to collect every possible photon to get the best image. So, the bigger is better because a large aperture can collect a lot more light than a small aperture.
You can buy a reflecting telescope with an aperture up to 16 inches and maybe more. This is a huge advantage over the refracting telescope. The big Newtonian telescope will show you amazing views of deep-sky objects.
Refractor vs. Reflector Telescope In Astrophotography
The most common choice for astrophotography is the refracting telescope. However, that doesn’t mean you can’t use a reflector.
Choosing between the refractor and reflector for astrophotography is a matter of preference, and there is no wrong choice here. No matter what you choose, you will be able to do astrophotography.
The one factor we can mention here is the price. Because if you want to do astrophotography with the refractor, you need a high-quality one with compound lenses to correct the chromatic aberration. Preferably triplet, which is very expensive even with a small aperture.
On the other hand, if you go for a reflector, it will be cheaper, but you will have to fight the comatic aberration and always perform perfect collimation of the mirrors before every astrophotography session.
Check out my article The Best Telescope For Astrophotography.
What Should I Buy, Refractor, or Reflector?
So what should you choose as the first telescope, refractor, or reflector? Well, this is a hard question but let me give you my recommendation after years of experience with telescopes.
If you are serious about astronomy and want the best beginner telescope to start with, go for any Dobsonian telescope. This Newtonian Reflector telescope on Dobsonian mount is the most affordable telescope even with bigger apertures. Remember that bigger is better in astronomy.
On the other hand, if you are not sure that you will be using the telescope very often, you may sometimes look at the moon or planets. Or you plan to take it on the camping trip to show the kids some object in the night sky, then you are good with a small refracting telescope. Later you can upgrade to a bigger reflecting telescope after you get hooked up on astronomy.
Recommended Reflector Telescope
Recommended Refractor Telescope
Who Discovered Refracting Telescope
It all begins with the lens many centuries ago- we don’t know exactly when because scientists argue about that. Some say that the lens is thousands of years old.
Archeological evidence indicates that there was some kind of rocky crystal artifact dated to the 7th century BC so-called Nimrud lens. We also have proof that even ancient Egyptians were using some type of lens based on certain hieroglyphs.
But the first oldest reference for using the lens is from Aristophanes mentioning a “burning glass” in his writings from 424BC. And it is confirmed that in the Roman period people used burning-glasses. Anyway, the lens was developing century by century until it was first used in a telescope.
It was in the 16th century when great mathematician and astronomer Galileo Galilei made his first simple telescope by using two lenses in a hollow tube. The first prototype of the refractor was created.
Nowadays, the refracting telescope is more sophisticated than Galileos’ first prototype, but they work on the same principle. It’s based on two lenses at the front, one for light collection and the second for magnification, and the hollow tube with the eyepiece at the end of the scope.
Who Discovered Reflecting Telescope
When Galileo Galilei created his first telescope and pointed it to the stars, he started a revolution in astronomy. People wanted to see more, and they were building bigger and bigger refracting telescopes. It was not long after they realized that it is not practical, and lenses suffer from chromatic aberration (rainbow colors around the observed object).
A few years after trying to resolve this problem, Isac Newton created a reflecting telescope prototype, the Newtonian telescope. He was using a concave primary mirror at the end with a secondary small diagonal mirror at the beginning and focusing on an eyepiece.
Surprisingly, we are using the same design even today. The main advantage of the mirror is that it doesn’t suffer from chromatic aberration. The light is only reflecting off the mirror, and it is not going through any lens like in a refracting telescope.
We can build much bigger and more efficient telescopes. The reflecting design is being used in almost all observatories on Earth. Even the Hubble telescope is a reflector with an aperture of 4.2m, and it is orbiting the Earth since 1990. It was the first space telescope.
Here are some of my favorite gear
Thank you for reading this article. I hope you found it helpful as you learn more about telescopes. Here are some of the gear I use and recommend.
Beginner telescope: This is by far the best beginner telescope you can buy. The Orion SkyQuest XT6 is the perfect telescope to start with. The aperture is big enough to see almost every object in the night sky and on the other hand, the price is so low for what this telescope can do.
My astrophotography telescope: I use only a newtonian telescope to do astrophotography. I use an 8" newtonian astrograph telescope.
If you want more recommendations please check my recommended gear section.