What Is The Difference Between A Newtonian And Dobsonian Telescope?

What Is The Difference Between A Newtonian And Dobsonian Telescope

Both the Newtonian and Dobsonian telescopes are extremely popular among amateur as well as professional astronomers. There are a few differences between the two. In this article, we’ll take a look at the differences between the Newtonian and Dobsonian telescope. As a result, after going through this article, you’ll understand which one you should go for. So, here’s the main difference between a Newtonian and Dobsonian telescope:

Both the Newtonian and Dobsonian telescopes are basically the same thing. The only difference is, Dobsonian telescopes have some extra features than the Newtonian ones. We can say, Newtonian telescopes with some extra specific features like altazimuth mount, thing mirrors, etc. make up the Dobsonian telescopes.

There are a lot of similarities between these two telescopes compared to the dissimilarities. To understand both of these telescopes better, we’ll take a closer look at each of the telescopes in turn.

Let’s first start with the Newtonian telescope.

Newtonian Telescope

As the name suggests, the Newtonian telescope was invented by none other than Sir Isaac Newton in 1668. It is also known as the reflecting telescope.

Before Newtonian or reflecting telescopes, people were used to refracting telescopes. Refracting telescopes use lenses to collect light and focus them in a single point. However, there were some issues with the lens. The most common one was the blurry or slightly distorted images.

Sir Newton solved this problem by using a mirror instead of the lens. The mirror reflected the light rays in front of it, in a single point. At that point, a secondary mirror is placed. The job of the secondary mirror is to reflect the light rays into a nearby placed eyepiece.

By this way, images were no longer blurry or distorted. Till now, this reflecting telescope is very popular and widely used.

Till now, various types of reflecting telescopes have been invented. However, the most easier one to build is the Newtonian telescope.

Newtonian telescopes are not made for much portability. Too much handling can disturb the alignment of the primary and secondary mirrors. As a result, you may often need to realign the mirrors before starting out.

Dobsonian Telescope

Dobsonian telescope was named after Sir John Dobson in 1960. The main aspect of a Dobsonian telescope is its mount. Dobsonian telescopes use an altazimuth mount, which Newtonian telescopes don’t. This is the main structural difference between Dobsonian and Newtonian telescope. Also, Dobsonian telescopes generally use thinner mirror than the Newtonian ones.

Why Dobsonian Telescopes Have Become So Much Popular?

  • The price is relatively much cheaper than other types of telescopes, however, the result is quite impressive
  • Great for amateurs who are looking for a budget-friendly telescope
  • The simplistic design makes it suitable even for absolute beginners

The main use of Dobsonian telescopes is to observe deep-sky extra-terrestrial objects. If you want to observe planets and galaxies, choosing a Dobsonian telescope will be a good bet. There are several reasons for that-

  • Dobsonian telescopes allow a large amount of light to be collected and focused into a single point. This means the image will be much clearer and sharp.
  • The large light-gathering capability makes sure this telescope can detect objects that are too much far
  • Dobsonian telescopes are designed with short focal length. So, they are comparatively smaller and much more portable.

We need to be sure of one thing when using Dobsonian telescopes. As these telescopes are generally used to observe the deep-sky, there should be less to no light pollution around you. If you live in a city, that might prove to be a problem. However, don’t worry.

In this article of mine, I’ve explained how you can use a telescope even within a city.

Newtonian vs Dobsonian telescope

Dobsonian vs Newtonian Telescopes

There are some specific features that turn a Newtonian telescope into a Dobsonian one. Here are the features in details:

Altazimuth Mount

This is the most notable feature of a Dobsonian telescope. Without an altazimuth mount, you can’t even imagine a Dobsonian telescope. These days, both the equatorial mount and the altazimuth mount have gained extreme popularity for their simplistic design and easy functionality. Both of these mounts can easily be rotated at all angles.

equatoiral vs altazimuth mount

Let me explain a bit the differences between these two mounts. With the Altazimuth mount, the telescope can go up-down and right-left which is pretty much intuitive. However, in case of equatorial mounts, the telescope can move in only one direction to track an extraterrestrial object- the right ascension.

Thinner Mirrors

The second defining criteria of Dobsonian telescopes is, they use much thinner mirrors than the Newtonian telescopes. These days, Pyrex mirrors are widely used to produce Dobsonian telescopes.


Regular Newtonian telescopes use fiberglass or aluminum to produce the tubers for the telescope. However, Dobson chose a much different but effective material for the tubes.

He chose paper, more specifically, hard paper (the ones we typically see in construction sites) for making the tube. This provided several advantages over regular telescopes including-

  • Higher robustness
  • Easier portability
  • Less chance of damaging etc.

These are the most major differences between Dobsonian telescopes and Newtonian telescopes. As I have said, both of these have many more things similar than differences. However, each of them has a unique application in different fields and both are extremely important for astronomy.

Final Words

I hope this article has clearly stated what is the difference between a Newtonian and Dobsonian telescope.

If you are a beginner, I’ll definitely recommend getting a Dobsonian telescope. They are much simpler to use compared to refracting telescopes. If you are just getting started, don’t look back and get yourself a Dobsonian telescope.

If you ask me, I’ll suggest the SkyQuest XT8 model from Orion. This is a classic Dobsonian telescope equipped with everything you’ll need for stargazing. The optics is 8 inches in diameter, so the light gathering capability is quite impressive. If you want to check the latest price at amazon, click here.

Lastly, I want to conclude this article by saying that, we can designate Dobsonian telescopes as a variation of the Newtonian telescopes. There aren’t many differences between them.




I have wondered how the Stars and Moons look like for many years. I’ve fallen in love with Cosmology since I was a boy. I am writing these articles to share my love for astronomy with you.

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