Telescopes are the tools that help us explore the big wild outer space, just like microscopes empower us to delve into the smallest dimensions. If you want to have your own telescopes to enjoy celestial wonders or quench your children’s interests, it’s one of the best human wishes. But what sort of it should you buy? There are different types of telescope, and choosing one (if you settle for one) might be challenging.
Different Types of Telescopes: Buyer’s Guide
Let’s start with the assertion that there are 3 types of telescopes. In fact, there are more. But the ones you may want to purchase for amateur purposes are just 3. There are certain modifications some researchers count as separate types, but we prefer to define them as… well, modifications. The basics are still here.
The basic telescope types
The present classifications often disagree about how many telescope types exist. We will select the 3 most common types of telescopes. Of course, radio telescopes are not included, as well as other purely professional stations that are too expensive for amateurs. Unless you compete with Elon Musk, but then again, who will dare to call you an amateur?
So, what are the two types of telescopes that started it? And what else can we enjoy now? Let’s visit them all.
Refractor telescopes are the most classical type, invented in the Netherlands in 1608. They utilize a system of lenses, redirecting the light into the pupil. Hence, the viewer sees the magnified image of the selected fragment of the sky. Refractor telescopes are popular today because they are the “default telescopes.”
These are rather expensive, but they tend to be smaller than the others and the simplest. They are the best if you need as strong magnification as possible and want to focus on a specific object.
The most visible disadvantage of affordable refractor telescopes is chromatic aberration. As light waves of different colors arrive at different angles, the image may be distinctively colored at its age. Some systems compensate for this effect but are more sophisticated and expensive.
Another one is that refractors are rather weak on aperture – the volume of light it catches. Given how dark the space seems, it’s crucial. Though there are refractor telescopes with a large aperture, they are way more expensive than other types, the costliest part of them being just lenses.
- Easy to handle and maintain;
- Great magnification abilities;
- The best for watching certain objects;
- Well protected from dust and moisture;
- Classical and intuitive.
- Prone to chromatic aberrations;
- Requires larger lenses for decent aperture;
Reflectors (Newtonian Reflector, Dobsonian Reflector)
This more advanced type of telescope was invented by Sir Isaac Newton in 1668. Reflector telescopes use a mirror system that sends the image to the watcher’s eye from the objective lens. Though this is a more sophisticated way to build it, even Elizabethan mechanics were able to reproduce it after Sir Newton. In addition, mirrors are easier to make than decent lenses, so overall, reflector telescopes are more affordable.
What are the downsides? First, by default, the image you get from a reflector telescope is upside down (that’s how mirrors work). You can use extra devices to align with the sky, so living with this inconvenience is easier. With them, the benefits outweigh even stronger.
The modification named Dobsonian reflector telescope is often recommended as the best for amateurs among all types of telescopes. It’s hard to disagree, given that a Dobsonian type (named after John Lowry Dobson) is the simplest to install anywhere you like and direct to any point in the sky. It’s an altazimuth mount on which a regular reflector telescope is installed.
Why reflectors of all kinds of telescopes? Because it’s the best-adapted one for constant moving. In addition, it suits for viewing nebulae and galaxies. Usually, for Dobsonian telescopes, the most lightweight mirrors are chosen, as they are mobile.
Dobsonian telescopes usually have large objectives and low magnification, which results in a wider field of view and good visibility of nebular objects. Other reflector telescopes may be more focused, with higher magnification, and suitable for viewing planets.
- Wide field of view;
- Better aperture;
- Correct colors;
- Rather affordable;
- Transportable (Dobsonian version)
- Lower magnification;
- Require more maintenance;
- Heavier and bulkier.
Catadioptric (MCT, SCT)
Also known as the Maksutov-Cassegrain type (MCT), catadioptric telescopes utilize both mirrors and lenses to deliver the image to the watcher’s eye. The sophisticated construction results in a long focal length placed in a small body, so short that it’s impossible to believe these shorties are that capable. In addition, this is a low-maintenance technology and, therefore, a great one for amateurs. But the win-some-lose-some rule applies here as well. Combining the pros of the two types of telescopes comes at a price.
Logically, the longer the focal length, the narrower the field of view, which can spoil, if not ruin your experience. These telescopes are great for focusing on a specific object (a planet, a star, a satellite), but they don’t provide great pictures of the starry sky as refractors do. So beautiful nebulae or galaxies will mostly stay out of the view, impossible to follow with a catadioptric telescope. They are also inferior to refractors and reflectors when it comes to aperture – simply because of their size, that doesn’t imply using large lenses and, thus, allows for catching less light.
It’s a subtype of Schmidt-Cassegrain telescopes (SCT). The main difference is the corrector lens shape. They are both used to reimburse the distortion caused by spherical mirrors. In a classic MCT, the lens is spherical and highly curved. In an SCT, the lens is aspheric, but the curve is so minor that it seems nearly flat. This has some practical consequences: MCT ones need more time to adjust to the temperature (because of the lens thickness), while SCT models adapt quicker. Also, the SCT solutions, other things being equal, have a larger aperture and are better for both observing and taking photos.
Whether you choose an MCT or an SCT, the maintenance of these telescopes is the trickiest. Does it mean you should forget about this type and leave it to the pros? No way. If it’s just certain celestial bodies you’re after, the MCT (or rather even SCT) is the right choice for you.
- No chromatic aberration;
- High quality, good contrast;
- Rather compact.
- Require lots of maintenance.
How do the SCT, MCT, and Newtonian compare to refractors for light gathering?
Despite all these modifications, refractor telescopes remain the most common type. But how do they compare in terms of light gathering? Well, as you may have read above, they all perform better in this discipline.
It doesn’t mean that refractor telescopes are all so poor at gathering light. But a model with large lenses (processed as they should be) will cost much more than a set of spherical mirrors, even with a corrector lens.
Among its rivals, if you need a higher aperture and decent quality, we’d recommend SCT models. They are already adjusted to balance the chromatic aberration. At the same time, they don’t require as much processed glass as refractors do.
Picking the right scope for you
If you look at the word “telescope,” you’ll see that the “scope” has the controlling interest. What is other proof necessary? If seriously, a scope (a.k.a. finderscope) helps you lose no time while searching for the right object in the sky – controlling your telescope. It’s attached to the main tube of your telescope, so after you’ve found the object, the main telescope already has it.
How do you find the right one? It’s mostly about convenience. The most common types are straight and right-angle ones which require different postures. Choose which is more comfortable, and then pick the type within this category.
Which type is right for you?
It depends on what you want to watch and photograph. In general, you may base your choice among different telescopes on the following considerations:
- Do you prefer skyscapes or certain planets and stars? For the former, reflector or catadioptric kinds of telescopes are better. For the latter, the classical refractor ones are still unrivaled.
- If you watch the sky, will you travel? If so, the Dobsonian telescope is the way to go. If not, a traditional mount is better.
- What about astrophotography? If yes, a good refractor or an SCT is the option. If not, any will do.
There are other options as well, including size and price. But if you’re sure of what you want, these considerations are secondary. Ask yourself one more question: are you sure you’ll settle for just one telescope?
How to choose a telescope
As you see, not all telescopes are created equal. Which doesn’t render bad those you consider inappropriate: they are just made for other purposes. Here are the parameters you should consider when choosing within a particular category.
Aperture: a telescope’s most crucial specification
Without sufficient light, you won’t see much. And this parameter is primarily defined by the shape of the lens.
You know, it’s how many times larger you see a certain object (or sky area) through the telescope. But it’s not always good to have it as high as possible.
Focal length and eyepieces
The focal length is the parameter dependent on magnification (or vice versa). The longer the focal length, the stronger the magnification and the less of the sky you see. A short focal length is better for wide pictures with nebulae and myriads of stars. The eyepieces partly define it: the shorter their focal length is (other things being equal), the greater the magnification. That’s why having multiple eyepieces for the same telescope is okay.
Types of telescope mounts
There are 2 of them: altazimuth and equatorial. While the former is the simplest mount with 2 motions, perfect for manual aiming, the latter allows for following a certain object across the sky, both manually and automatically. We have already seen a version of altazimuth mount named after John Dobson.
A finder (or a finder scope) is the tool for quickly finding a certain object in the sky. Without it, one would need to wander through the celestial jungle for much longer.
It seems easy to understand, but there are some nuances too. For example, a good refractor telescope can be more expensive than any other type, but if you want to see Venus, Mars, or Saturn, you’d still better opt for this.
What are you waiting for?
We’re all born under the sky, and lack of interest in it is… well, I won’t say “an insult,” but something too ignorant. Even if you have never felt inclined to raise your eyes up high, it’s a different feeling with a telescope. Just try it, and you may become a fan even if you don’t expect it.
FAQ on Telescope Types and Their Issues
Each type of telescope deserves its own FAQ section. Welcome to the comments where you can ask your question; so far, let’s reply to some of them here.
Which type of telescope is better and why?
It depends. For objects like planets or stars, a refractor is better. For galaxies or nebulae, a reflector is the best, the Dobsonian-style one being optimal for frequent traveling. MCT and SCT are great for celestial bodies, equally suited for astrophotography but less expensive than pure refractors.
How many types of telescopes are there?
While many disagree, we decided to select three. According to our classification, the basic telescope types are refractor, reflector, and catadioptric. Within each type, there are subtypes. For example, a Dobsonian type is a reflector with a simple altazimuth mount and high portability. SCT and MCT, both catadioptric, are different because of their corrector lens shape.
Why does the Moon look fuzzy?
It may be all about focusing. If you have done the focusing to no effect, and your telescope is a reflector type, you probably need to do the collimating. This procedure is a regular part of maintenance for reflector telescopes, ensuring all the mirrors are correctly positioned. Finally, you can just wipe the lens with a cloth or help it with a special brush.
Why can’t I see the Andromeda Galaxy?
The Andromeda is the only galaxy seen from Earth. Sometimes, even telescopes can’t help you see it. There are multiple reasons for that:
- The sky is clouded or just too dark.
- Your telescope’s aperture is insufficient for that.
- You see but don’t realize it (narrow field of view).
You may try to find it with a larger aperture telescope or choose a clearer night for your next observation.
So, Should I Buy a Reflector or Refractor Telescope?
Well, if you want to watch the sky, a reflector one is better. If you are interested in certain celestial bodies, there is nothing like a good old refractor. In fact, all the types of telescopes for astronomy are there for a reason, and one day you may end up having all of your roof armed with tubes.
Which one are you after? Have you had any experience with certain telescope types? If so, welcome to the comments where you can share it or ask a question! Waiting for your reply, like we are SETI!
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