Before you buy your first telescope, read this article
Buying your first telescope can be confusing. There are many options for buying your first telescope, some look very intimidating, after all telescopes are advanced instruments and you are just getting started in your astronomical journey. I hope that this article will help you understand the decision making process much better so that you do not buy the wrong type of telescope for what you expect to do. So I hope you read this article before you buy your first telescope.
There are so many options, it’s hard to know what’s best for you.
As you read this article you will find that there are so many types of telescopes out there and it can get very confusing for someone getting started. You might be getting conflicting advice, or maybe you are not sure about the quality of the advice you are getting. My aim in writing this article is not to tell you what telescope to buy, but rather to help you understand yourself what telescope you are more likely to enjoy the most. After all, we all have different interests, requirements and even physical abilites. All these matter if you want to truly enjoy owning a telescope.
It is best to learn a bit about astronomy before buying your first telescope
An unfortunate thing that I have seen so many times in the local astronomy community near where I live would be a person totally new to astronomy would have interest in buying a telescope and someone will tell them to go buy a specific model of telescope. This sounds easy and many beginners might feel this person is being a good friend. However, I strongly disagree with this approach. My personal belief is that you should first start learning about astronomy before you think of buying a telescope. You do not need a telescope to start learning about astronomy a few weeks researching could lead to a far more rewarding first telescope experience.
Why learn about astronomy first?
So why do I recommend you learn astronomy first? It is very simple, there is not one telescope that does it all, and if there was one telescope that does everything, I can guarantee you it would be a very expensive instrument with lots of compromises. By taking the time to learn a bit of astronomy first, you will start to understand what area of astronomy interests you the most. You will start to for example understand as novice stargazers what a telescope can do and what it can’t do. You will learn about the impact of light pollution, time of there year, phase of the moon size of the telescope etc… Should you take the time to build a basic foundation in astronomy, you could save a lot of money and avoid disappointment. I will give you an example, maybe you start really enjoying observation open star clusters and also get into observing double stars. For this type of astronomy a large high magnification telescope might not be the best telescope for you. You are more likely to enjoy having a high quality modest sized refractor. Don’t worry about words like refractor, I will explain them further into the article.
Where can I learn about astronomy?
20 years ago, this would not have been an easy question to answer, but these days there are so many options to learn about astronomy. Let us start with the best free learning resource in the world. Search YouTube! There is so much content on YouTube and you can learn a lot from it, I do not recommend you start searching YouTube for what telescope to buy, but rather search for videos about how to observe. For example, how to observe the moon, how to observe planets. These videos will give you a better understanding of how different types of telescopes are used.
Many places have astronomy clubs, go online and do a search for astronomy clubs, don’t search only in English language, search in all the languages you speak. Also, remember that in today’s world many clubs don’t bother to make a website, so you might need to search on Facebook and Instagram. The amateur astronomy community is very active online and it should not be too hard to find people to link up to if you perform an active search.
Planetariums are a great starting point, I have found that most of the countries I have been to have one, but they are generally not well promoted, look them up in your favorite maps program, personally I have found the most success searching in Google Maps.
Start making friends with people with similar interests in astronomy on social media, many countries have started active WhatsApp groups where they discuss astronomy, just be prepared for lots of bad jokes about hiding your astronomy purchases from your significant other! The amateur astronomy community has it it’s own sense of humor and you will grow to like it.
Use a telescope, learn what it feels like!
It is really important that you use several types of telescope before you make a purchase, sometimes it is hard to get in touch with people who will let you use telescopes, but hopefully after following the steps in the previous section of this article, you would have built up relations with a few astronomers. Many clubs have group outings and for the more serious astronomers they have more cozy small group astronomy outings. If you can make it to these small group outings, you are in luck, then you will be able to get the attention of the telescope owners and discuss their instruments without a crowd.
Understanding the types of telescopes
Now that you have started to learn a bit about astronomy, when I start to explain the types of telescopes out there, you will feel less intimidated by all the technical terms. By now you have enough knowledge to research types of telescopes and make a more informed decision. I will now take the time to explain to you the main types of telescopes and their mounts. I will not discuss every single type out there, but rather, I will focus on the types that a first time buyer is most likely to come across.
The telescope itself, also known as the optical tube assembly (OTA)
First thing you need to understand, is that the telescope, is only the lens part of the instrument, not the tripod and other devices that are used to hold it up and point it around the sky. Astronomers call this part the optical tube assembly (OTA). Some telescopes are sold as a bundle with these other parts, and some are sold separately and you choose the other parts according to your needs. For this section of the article, we shall focus on explaining only the OTA, in a later section of the article I shall explain the mount (you can think of it as the stand or tripod combined with the bit used to aim the telescope). This is a simplified guide and is intentionally leaving out many details that can intimidate a person just getting started, the idea is to just get started, you can get further details about each design from all over the internet.
Size (aperture) and other features
Before we discuss specific telescope types, let us discuss common features that will determine what you can do with a telescope. This is not a detailed discussion of every feature, just the main ones that beginners should understand. The features are not listed in any particular order of importance, each and every one of these items is important in its own way.
- The size of the main lens or mirror of the telescope when measured across it (diameter) is the aperture of the telescope. The larger the telescope the more you can push the magnification. If you have a small aperture telescope and push the magnification too far, the images will be low in contrast and blurry and you are unlikely to be pleased with the results. On the flip side, if you have very large telescope, lets say for example larger than 10″ (250 mm), you are more likely to see negative effects from turbulence in the air. In general aperture is very important for visual astronomy at high magnifications. Another factor to consider is the aperture of the finder scope (the little scope used to aim the big scope), some telescopes come with tiny finder scopes with 10 mm aperture, these are too small to be useful, even 30 mm finder scopes are barely adequate, I generally recommend you get a 50 mm finder scope
- Red dot finders are an alternative to finder scopes to point the telescope, they work by showing you a floating red mark that you can use to aim your telescope. The low-quality ones are completely useless. For red dot finders, you need a high quality one with good anti-reflection coatings and the ability to dim the pointing reticule to a very faint brightness. A bright red dot in the middle of the view will make it difficult to see the star you are trying to aim at.
- Eyepiece sizes. The two most common eyepiece sizes are 1.25″ and 2″ eyepieces. The 2″ Eyepieces are generally better as they give you a wider view to look through but tend to be more expensive. Any telescope with the smaller size 0.75″ eyepieces should be considered a children’s telescope and is generally not considered a serious instrument. The eyepieces of the telescope control magnification. You take the focal length of the telescope, usually marked on the telescope, and divide it by the eyepiece focal length, and you get the magnification. So, a 1000mm telescope with a 10mm eye piece will give 100X magnification. Most of the time the eyepieces you get with your telescope are very basic in performance and this is one of the things you can upgrade to improve the performance of your telescope. Look for anti-reflection coatings, they generally look like a green coating on the eyepiece glass, these will give better views of the sky
- The focuser is the part of the telescope that you adjust to make the image sharp. Look for a smooth moving focuser, better focusers can also handle heavy eyepieces and cameras. The focuser also will restrict what size eyepieces you can use. The focuser is usually one of the places cheaper telescopes cut costs to bring the cost of the telescope down. A low-quality focuser can really spoil your enjoyment of astronomy.
The Newtonian telescope was invented by Isaac Newton in 1668, it is very popular because it is cheap to manufacture in large sizes compared to other designs. In fact, it is simple enough to manufacture that many people would make their own at home. Many people make their own at home because they can make a higher quality mirror than what they can buy ready-made. The Nnewtonian telescope consists of one curved mirror and one flat mirror at 45% degrees angle. Unlike most telescopes, you look through the Newtonian telescope from near the top not from the rear of the telescope. Here are some advantages of this design:
- Relatively low cost for entry level models even at modestly large apertures.
- Widely available from many manufacturers, so lots of choices for entry level buyer
- No color fringes around bright objects as it does not have the chromatic aberration problem
- Stars show spikes in a plus sign pattern, we call these diffraction spikes, many people find them pretty
- If you need a fast telescope for astrophotography, cost wise it is hard to beat a Newtonian
Disadvantages of the Newtonian telescope:
- The same diffraction spikes that people find pretty, many people hate them.
- The mirrors lose alignment and every time you transport the scope, you need to align them. This is very easy and quick to do, but many beginners are not comfortable with this process.
- They tend to be very long in size.
Refracting telescopes, also known as refractors
Refractors are what classically think of a telescope, they are made up of a series of lenses that you then connect an eyepiece in the rear to look through. Refractors range in quality from truly terrible telescopes that most people would regret buying all the way to some of the best telescopes out there in terms of sharpness, contrast and clarity of the image. Refractors are more difficult to make than other designs, so a good refractor can get very expensive. 3 main things affect the quality of a refracting telescopes, the number of glass lenses, the type of glass being used for the lenses and the F ration. Cheap glass makes the image have lots of color fringes around stars and bright objects. For example, you will see purple halos around bright stars. Improving the glass quality and increasing the number of glass elements will enhance the sharpness and reduce or remove this color fringing (also referred to as chromatic aberrations). Another thing that can help is slow F-ratio, which simply means the telescope has long focal length compared to the size of the lens. Think of focal length like the native magnification before you put an eye piece. This will compensate for a lot of the flaws of the lenses and make the image sharper but will result in a dimmer image. High quality refractors are known to have some of the best images possible of any telescope design, but a good refractor can get very expensive, a 6″ refractor can cost up to Euro 7000, while a 6″ Newtonian on a Dobsonian mount can be had for as little as Euro 700. If you are looking to buy a refractor to start with but don’t want to spend a lot of money, I would recommend an f11, to start with, should give very sharp views for very little money.
Schmidt Cassegrain telescopes (SCT)
This is one of the most popular amateur telescope designs on the market. It consists of two curved mirrors and a corrector plate in the front. You will find at least one of these with every club. Currently, there are only 2 companies making these in mass production, Celestron and Meade. There is an Italian company making a premium version, but they are very pricy. This design is known for its compact size and high magnification. Large sizes, while still more expensive than Newtonian design, are still relatively affordable. Many of these are sold attached to a mount as one unit. As of the time of writing this article in May 2022, there is a global shortage of this design of telescopes and the latest estimate I got from the manufacturer was 2 years waiting list to get stock for our store.
- The design is compact compared to the magnification
- Still needs alignment, but alignment of mirrors can be done a single screwdriver or LN Key depending on the model and no other tools
- No diffraction spikes
- Lower contrast than Newtonians, because they tend to have a bigger obstruction in the front
- Can suffer from thermal currents (hot air moving inside the telescope), This means you don’t get the best possible views till the temperature inside the telescope has balanced with outside temperature.
- Some models can be operated as a long focal length telescope, a medium focal length and very fast F2 setting for photography.
The Muksatov design telescope is commonly sold as an entry level telescope, in design it looks similar to an SCT telescope but the corrector plate is much thicker and the reflective coating for the secondary mirror is directly on the corrector. It shows as a shiny circle in the front of the telescope. Muksatov telescopes, when well made, are excellent for observing small but bright targets such as planets, they are not good at observing large targets that take up a large area. Muksatov telescopes are mostly long focal length telescopes and are great for high magnification views. They also take a very long time to stabilize in temperature till they are ready to observer with, as much as 45 minutes is pretty normal. However, as mentioned earlier for observing at high magnification such as the craters on the moon or planets, these are outstanding telescopes.
A telescope mount is the part that carries the telescope and points it around the sky, This is a very important part of the telescope and many people would argue that it is even more important than the telescope itself. This might sound counter intuitive, but if the mount is not stable, the entire telescope could be shaky and frustrating to use. Also, if it is not smooth to move, it might be hard to aim the telescope at high magnification. Some mounts are easier to use than others. Here, I will give a broad introduction to the types of mounts.
Alt-Azimuth vs. Equatorial mounts
There are two types of mounts. Altazimuth mount (sometimes called AltAz mounts) are simply mounts that rotate left right and up down, they need minimal set up and don’t need any alignment to get started. Equatorial mounts on the other hand are tilted at an angle, they are designed rotate on only one axis once they are pointed at the target. This makes it easy to follow the target and if you are taking photos, it is almost absolutely necessary. However equatorial mounts need alignment when they are set up and for a beginner this can be a very intimidating and frustrating process. Once you are used it it, it is not that difficult.
Dobsonian mounts are very highly recommended for beginners. They are the simplest type of alt-azimuth mounts, they are usually made from a wooden stand that holds the telescopes on two sides and it has a rotating base. You simply push the telescope to where you want to point it. The Dobsonian design was designed by John Dobson, who passed away in 2014. He used to run telescope building workshops for people and was famous for taking his telescopes out on the sidewalk to let people observe the moon. The Dobsonian mount is easy to use and comes in various sizes from little tabletop telescopes all the way to giant telescopes with mirrors bigger than 20″ and needed a ladder to use. If you are looking for a low cost, easy to learn to use mount that is reliable, get a Dobsonian mount.
Manual Equatorial mounts
Manual equatorial mounts are equatorial mounts but without fancy electronics to point them and automatically track the target. You need to polar align the mount each time you set it up and pointing the telescope is confusing for a beginner, I don’t recommend it unless you feel you won’t be confused by the rotation at an angle. Also, for Newtonian telescopes, it is very difficult to use an equatorial mount of any type as the eye piece will keep changing orientation. Not all, but most manual equatorial mounts being made these days are of low quality.
Electronic (Go-T Mounts)
Electronic mounts, also known as GoTo mounts have little computers in them and they will automatically point the telescope to a target you select on the remote control and automatically track it. Many of them will have 10s of thousands of targets programmed into their remotes, those targets are mostly useless since most of them are probably too faint to show up on the size telescope a beginner will have. With the exception of very few models in the market almost every single Go-To mount needs some sort of electronic alignment process each time you set it up.
Go-To Equatorial mounts
Go-To are the same as manual equatorial mounts except that they usually have automated pointing and tracking. As with any equatorial mount, they still need polar alignment and they need electronic alignment.
Go-To Alt-Azimuth mounts
Go-To Alt-Azimuth mounts are far simpler to operate than their equatorial equivalents because they do not need polar alignment and the electronic alignment process tends to be simpler. However, they still need electronic alignment.
Are computerized telescopes easier to use?
The answer is yes and no. Computerized mounts have a much steeper learning curve compared to manual mounts. For someone completely new to the hobby it can be very difficult to learn. However once you have gotten past the initial issues, it becomes far easier to find targets than manual mounts. Low cost electronic scopes tend to have terrible accuracy and you are better off having a manual mount or a more expensive electronic mount. Computerized Altaz mounts are easier to use than computerized equatorial models.
Other considerations in choosing a telescope
When buying a telescope, you have to take into account other considerations such as storage space. Another thing to consider, is that if the telescope is too heavy for you to handle or too big to fit into your car. Maybe the telescope is too short for you and you are uncomfortable using it, or maybe it is too tall and you have to keep using a small stool to reach the eye piece.
To sum it all up
Buying a telescope is a complicated decision for when you are just started, but the journey of discovery should you do it the correct way is very enjoyable and will result in a far more satisfactory first purchase when compared to just going and buying one or listening to advice from somebody who did not take into consideration how you are actually going to use the telescope.