Astronomy Telescope Types

At one time in your life, you may have gazed up in the sky and got fascinated by the twinkling stars on a starry night. The picturesque night sky dotted with millions or billions of stars and other heavenly bodies can be breathtaking especially for someone with a passion for astronomy. And there is no better way of observing and marveling at the universe if not by use of a telescope.

That being said, there’s no need for investing a fortune in gigantic telescopes when you can just choose from the available vast array of affordable telescopes and accessories to advance your amateurish astronomy skills. As a novice stargazer, you can start with a Maksutov-Cassegrain or turn to Schmidt-Cassegrain when observing your favorite constellation in a clear night sky. If that is not enough, you might want to set your sights on a Dobsonian, Newtonian or go for the state of the art Refractor types of astronomy telescopes on the market today.

For general purpose observers, the aforementioned types of astronomy telescopes can provide you with everything necessary for your space exploration right from your backyard, balcony or on a nearby hill. Learn more about these five types of telescopes in the following discussion so you may decide which one suits your needs.

1. Maksutov-Cassegrain

Maksutov-Cassegrain telescopes-commonly referred to as Mak-Casses-are almost similar in design to Schmidt-Cassegrain (SCT) but there are underlying differences hence the name. This astronomy telescope type is well suited to various applications such as terrestrial observing, stargazing and photography. Being catadioptric in design, Mak-Casses use both mirrors and lenses. In other words, they are typically reflecting telescopes with a corrector lens included to eliminate aberrations resulting from its mirror design.

How does work? Normally, the incoming light from objects goes through a meniscus corrector (corrector lens) located at the front side of the telescope. Then it is reflected from the concave primary mirror situated right at the back of the telescope. From there, the light is reflected towards the front side of the telescope. Once more, the same light is reflected using a small convex or secondary mirror. This way, the light travels back via the hole located in the primary mirror to the eyepiece at the rear of the telescope for visual observing.

When it comes to notable features, Mak-Casses seem to have it all. With a focal length of about 5 to 7 times the length of the tube, this model of astronomy telescope can effectively magnify its focal length to virtually make the scope a little longer than you can imagine. Its primary mirror has a focal length that is 3 times its diameter making it possible to focus the light to the point 21 inches in the front mirror. The secondary mirrors are designed to provide you with a magnification factor of 5 times which translates to an effective focal length reaching 105 inches.

Maksutov-Cassegrain: Pros and Cons

Pros

Shorter overall length
No chromatic aberration
No thermal degradation
Excellent correction of the spherical aberration
Gives a good contrast
Does not have spider veins
This is inexpensive models

Cons

Meniscus lens makes it heavier
Long cool-down time
Larger aperture makes it expensive
Obstruction from the secondary mirror
Aperture ratio gives a small field view.

2. Schmidt-Cassegrain

Also known as SCT, Schmidt-Cassegrain is one of the most popular types of astronomy telescopes. They are reputed for their versatility as well as compact optical designs. The fact that they are two times the size of their aperture, it means that you can easily carry them around. Mostly they are suitable for photography and terrestrial observing not forgetting stargazing. The latest models are computerized for easy use.

Given that Schmidt-Cassegrain telescopes are known to be catadioptric in their designs it means they use both mirrors and lenses. Even though they are primarily reflecting telescopes, these astronomy telescopes use corrector lens to help in the elimination of aberrations. The incoming light goes through the Schmidt corrector lens or plates at the front section of the telescope. Then the same light is reflected from the concave primary mirror at the rear which in turn reflects the light using a small convex secondary mirror through the hole in the concave primary mirror towards the rear side of the scope at the eyepiece.

SCT telescopes come in various sizes ranging from 5 inches to 16 inches. In between these sizes, there are several models with different features in terms of mount features and tracking capabilities. A large number of SCTs are usually fork-mounted for easy setup and use but may require an equatorial wedge for longer exposure imaging. For the high-end SCTs, you may need to purchase a heavy-duty German equatorial mount for better stability.

Schmidt-Cassegrain: Pros and Cons

Pros

Short length
Very particular handling
Portable
Viewing is comfortable
Its
thread provides a wide range of telescope accessories for connection
Rapid and easy setup

Cons

More costly than the Newtonian type of comparable aperture
Larger secondary mirror compared to the Newtonian telescope

3. Dobsonians

Dobsonian astronomy telescope type can be compared to the Newtonian telescope on the basis of being optically identical. Their differences emerge in the manner with which they are mounted. This type of telescope has what is known as a lazy-Susan type of base that normally swivels from left to the right while the whole structure rides on its two hubs allowing motion up and down. A well designed Dobsonian telescope moves easily in one direction but maintains its position in place when needed.

For beginners, this is the right telescope to use due to its lack of automatic tracking features making it a perfect choice for visual observing. When it comes to the way Dobsonian works, there are no differences in the Newtonian way of working. The light is usually reflected off the primary mirror to a secondary mirror located at the top side of the telescope. On the other hand, everything is operated manually in an alt-az (up-down/left-right) or altitude-azimuth configuration.

Dobsonians: Pros and Cons

Pros

Affordable
Ideal for stargazing
Easy to use
A good choice for beginners

Cons

Not versatile like the Schmidt-Cassegrain or refractor
Not suitable for terrestrial viewing

4. Newtonians

Newtonians astronomy type of telescopes is less expensive compared to refractors of the same size. This fact alone makes Newtonians telescopes to be a popular design. Contrary to a common belief that telescopes work by magnifying objects, Newtonians telescopes gather more light than an observer’s eye could especially for the purpose of astronomical observing. To achieve this feat, reflectors collect light by the help of a primary mirror placed at the back side of the telescope.

The light is then reflected back up the tube of the telescope to a smaller flat secondary mirror. This mirror is tilted at an angle of 45 degrees in order to redirect the light away from the telescope tube to facilitate viewing. The secondary mirror is placed on a spider which consists of 4 metal vanes causing diffraction spikes. However, Newtonian telescopes have a tendency f producing inverted images that make it a perfect choice for stargazing.

Newtonians: Pros and Cons

Pros

Cheap to manufacture
No chromatic aberration
Good contrast
Light in weight
Obstruction is relatively lower
Availability of many variants
Dobsonian construction is possible

Cons

No automatic tracking of its features
Not suitable for photography

5. Refractors

Refractors were the very first types of telescopes to be invented before the introduction of reflecting telescopes. Refractors work by collecting light using the objective lens at the front or skyward end of the telescope. Normally, the objective lens is made up of more pieces of glass designed to focus the amount of light to a particular point at the back side of the telescope. This is an area where the eyepiece is located for viewing purposes.

Refractors have a reputation for providing a correct and detailed image whereby everything appears right side up. As such, refractors are regarded as multi-purpose telescopes designed for both stargazing and terrestrial observing. Refractors types of astronomy telescopes are divided into two basic types. These are achromatic and apochromatic with their differences lying in the quality of their objective lens especially when correcting chromatic aberration.

Refractors: Pros and Cons

Pros

Great classic design
Good contrast
No obstruction
No thermal delegation
Collimation not necessary

Cons

Chromatic aberration
Blurring if not corrected
Costly at larger apertures

Final Verdict

There are different models and designs of astronomy telescopes for both amateurs and professional stargazers. Given that different people have different tastes and preferences, the choice of their ideal telescopes would certainly be influenced by many factors key among them being the budget. From the information above, you can easily pick your perfect telescope type to help you enjoy both terrestrial and astronomical observing in the comfort of your home or while on your next adventure.

Additional Readings

I hope this article has helped demystify for you the different astronomy telescope types. And I certainly hope you’ve enjoyed reading this article and have found it both interesting and useful.

Please check out some of my other equally interesting articles:

1. Maksutov-Cassegrain

Maksutov-Cassegrain: Pros and Cons

Pros

Cons

Recommended

2. Schmidt-Cassegrain

Schmidt-Cassegrain: Pros and Cons

Pros

Cons

Recommended

3. Dobsonians

Dobsonians: Pros and Cons

Pros

Cons

Recommended

4. Newtonians

Newtonians: Pros and Cons

Pros

Cons

Recommended

5. Refractors

Refractors: Pros and Cons

Pros

Cons

Recommended

Final Verdict

Additional Readings