Telescope Buying Guide: How to Stargaze

You have decided that astronomy interests you, and let us tell you, this is actually quite a good time to become an amateur astronomer. Because the current market offers a plethora of great telescopes and accessories, and this is not such an expensive hobby anymore. With this telescope buying guide we expect to help you to choose the perfect telescope for you.

However, this also means that making the right choice is much harder, especially if you don’t know what and where to look for. Such a variety of choices also includes countless hours of research, so that you make sure the model and type of the telescope you choose, is the right one for you. Luckily for you, we have done all the research and will help you out in this quest.

In this telescope buying guide, we will talk about everything you should pay attention before making the final telescope choice. We will explain the available telescope types, and then focus on their key features. But first, let’s start with some basic questions you should ask yourself in order to make the best choice.

To choose a telescope you have to know your needs, experience and budget and we have to take into consideration:

  • Experience level

You need to consider if you need a telescope model for beginners, intermediate or experts. This will help you in defining the type, model and define the budget.

  • Objects to explore

You need to know what objects are you planning on using the telescope. For example, will it be looking at planets and the moon or opened skies, or for ground based objects.

  • Exploration place

You need to know what conditions will you be facing. For example, will you use it in places where there’s a good atmosphere as in a field where there’s no light pollution and the air is clear, or in a city, where you have bad conditions due to light and air pollution.

  • Mobility

You need to think about where will your telescope will be positioned. It will be in your home (fixed position), or you will be taking it outside and transporting it every time. This will help you in defining whether you need a robust model that will survive all the outdoor trips, or a more fragile model that will be fixed in your home.

  • Budget

You need to define your budget before starting the search for a specific model. Are you on a tight budget, or maybe you plan on searching for medium cost models, or if your budget is without a limit, in which case you can look for the high-end models.         

 

Which Telescope is the Right One for Me? -Telescope buying guide-

 
As we mentioned in the previous section of the article, defining your level of expertise on the subject of telescopes, as well as your budget, is essential. So, here are some pointers in what telescope types you should be looking for, based on your experience level and your budget:

 

 

 

 

  • Beginners with tight budgets

Here in our telescope buying guide, we can include all of us that we want to explore the sky, but without spend a fortune, maybe just to start in astronomy and learn the basics.  In this category, we will find the best telescopes under 200$ and they will meet our expectations.

Minimum options are a refractor with an aperture of 2,36” (60mm), or a reflector with an aperture of 4,5”(114mm). Finding a refractor with a correct price up to 4”(100mm), or reflectors up to 6”( 150mm).

(Discover our review for the Best telescope under 200)

 

  • Intermediates with a medium budget

If you really like that hobby, ini our telescope buying guide we encourage you to buy one telescope between 250$ to 1.000$. In this range you will find good reflectors, refractors and good compounds too. In addition, in this category most of them are motorized, so you will find easily the objects that you will want to see.

Here you could find telescopes to start practicing astrophotography and take that amazing pictures of the moon or galaxies.

With this budget you can expect to find good refractors above 4”(100mm), reflectors between 6”(150mm) and 8”(203mm) and compounds up to 10”(254mm).

(Discover our review for the Best telescope)

 

  • Hobbyists

In this category in telescope buying guide, we can include all telescopes with a great quality and power that are going to permit you, exploring any object in the sky. They are perfect if you plan to stargaze outside the city and is not a problem to move heavy equipment.

With a few more than 1.000$ you will find perfects telescopes for you. However, if you want to buy the best of the best, you have to take in consideration, first, one thing:

Where are you going to stargaze?, why we ask? Because if you want to explore the deep-sky inside the city or close, you have a problem, the polluted skies. This are going to limit the objects that you can see, independently of the specs of your telescope.

For that we do not recommend you to spend much more than 1.000$. Unless, you are going to enjoy good atmospheres conditions.

Refactors above 4” (100mm), reflectors above 8”(203mm) and compounds above 10”(254mm) are the telescopes that you are going to find.

(Discover our review for the Best Telescope for Hobbyists)

 

Telescope buying guide-How does a telescope work? Telescope Specs

 

Just like with any other purchase, before you actually buy something, you need to get as familiar as possible with how it works. What parts and features you should be keeping an eye on, so that you make sure the model you choose at the end, will suit your needs, but your experience level as well.

The same applies for telescopes, and before you get any deeper into the matter, you need to know the difference between the telescope types, as well as the advantages and disadvantages of each type and we’re going to show for you in this telescope buying guide.

 

Telescope types (Refractors vs Reflectors vs Catadioptrics)

             

Even though, when you start browsing through all the models on the market, it might seem that there are numerous types because there are so many different shapes and sizes. However, telescopes can be simply divided into three types: refractor telescopes, reflector telescopes and catadioptric telescopes.

 

    Refractor

Telescopes that have an eyepiece on the one end, and a convex objective lens on the other, are called refractor telescopes. In fact, this is exactly the type of telescope that pops up in your mind when you think of telescopes.

In addition, this is actually the type of a telescope that allowed Galileo, back in the early 1600’s, to spot Jupiter’s moons, and Saturn’s rings. These types of telescopes deliver an image with a higher contrast, and the best models of this type are quite expensive.  

PROS:

  • They have a rather simple design, and are quite easy to use
  • They work best for ground based objects
  • The optics are protected with a sealed tube
  • They need no maintenance and are sturdy

CONS:

  • They are not the best choice for objects that are faint
  • They are usually bulky and heavy
  • They offer less value when compared with reflector type telescopes

 

    Reflector

Instead of using an objective lens like refractor telescopes, reflector telescopes use a concave mirror. And, unlike having a sealed tube like refractors, reflector telescopes come with one end opened. The part of the telescope called the Primary, is actually the mirror that sends up a light “cone” through the tube and the part that intercepts that light and sends it to the eyepiece located on the side of the tube, is the second mirror, which is called the secondary.  Unlike refractor telescopes, that are more expensive to manufacture, thus at a higher-end of the price scale, reflectors are actually cheaper to manufacture, and are more affordable.

PROS:

  • They are better for objects that are faint
  • They deliver a very high quality of the image
  • When compared to refactor telescopes, they offer more value than refractors
  • They are lighter in weight and more compact than refractors

CONS:

  • The open tube is prone to dust collecting
  • It needs maintenance
  • Can not be used for objects on earth

 

    Catadioptric

This is a type of telescope that is basically a reflecting telescope. But also comes with a top positioned correcting lens, which actually forms the image. As for the design, most of this type of telescopes, come with a design that is known as the Schmidt-Cassegrain design. This means that the light goes through the corrector, then reflects off the primary, then the secondary, which is curved, and at the end, goes through the main mirror hole, and ends in the eyepiece.

PROS:

  • They are great for viewing objects that are faint
  • Can be used for viewing earth objects
  • Optics are protected with the sealed tube
  • This type is great for those who want to practice Astrophotography

CONS:

  • Come with a higher price tag
  • They have a bulky appearance and are large
  • Having a second mirror means that the brightness is reduced

  

Telescope buying guide-Aperture

 

Aperture is the diameter of the telescope’s main optical component, which can be a mirror or a lens. Aperture is actually the most important feature you should consider, because this determines what you will be capable to looking on the sky in the night. This feature is what determines how bright the picture will be (how much light it the telescope can gather), and how sharp the image is (the level of power resolving).

So, logically, the bigger the aperture value, the better for you. For example, if you use a 6-inch telescope when looking at the moon, you will be able to differentiate craters that are small as just 1 mile in the diameter. On the other hand, if you use a 3-inch one, in the same conditions, the smallest size of the crater you will be able to notice, are the ones that are 2 miles in diameter.

Furthermore, if, on a moonless night, you point both the 6-inch and the 3-inch telescope toward the sky, the difference would be even more noticeable, because the bigger mirror has a greater light collecting surface, 4 times greater to be exact. Which means the 6-inch mirror telescope would deliver a 4 time brighter picture. If you want to get technical and use the proper Astronomical terms, the 6-inch mirror telescope offers  one and a half magnitudes brighter image.

 

    Brightness

Brightness of a telescope is defined by the following formula Pi*(Ø / 2)^2 / Pi*(5,5 / 2)^2.

This means that the smaller the focal length (F) is, and the bigger aperture (A) is, more brighter will the image be. This is important to know if you plan using your telescope for Astrophotography.

 

    Resolution

Resolution is expressed by “arc” and you can calculate with 116 / Ø. It is the telescope’s ability to show individually two objects that are close. Logically, the higher the resolution, the better the quality of the image.

The telescope’s resolution, or the resolving power, represents a measurement of its ability to distinguish small details of the observed object, or to differentiate two objects that are in close proximity of each other. This is important, for example, when you are looking at two stars that appear close to each other, and the borders seem to fade, or when looking at the Moon and trying to see fine details.

The formula to calculate the resolving power of a telescope is Resolving Power = 116/D (in arc seconds – 1/3600 of a degree), where D is the objective of aperture in mm.

Example:

 

(Ø) ApertureTelescope luminosityTelescope resolution
10,00 inch254mm2133 times0,456 ”arc

 

     Maximum useful magnification

 

This is an important concept you need to understand before deciding which type and model of a telescope you want to buy. As we already highlighted, aperture is the most important thing when it comes to telescope’s overall usefulness. But some astronomers will still say that magnification (or “power” as many refer to it) should also have an important role in your telescope buying decision. To a certain degree, we agree that magnification is important, but it is definitely not the factor that should be the final one in your decision.

The eyepiece you use, will largely determine your telescope’s magnification. This actually means that you can change the magnification power of the telescope by simply changing a certain magnifying power eyepiece, with a more powerful one.

This further means that when you see ads such as “800x magnifying power”, you should not get too excited because, first, is a common signal of a low quality telescope. Then, the truth is, any telescope can have an infinite range of magnification and it will magnify 800 times. In general, this means that even a telescope with small aperture can have large magnifying values. But it will actually be useless because the image would be unclear.

To put all of this in layman’s terms, take a TV screen for example. You have probably noticed that the closer you get to it (the more we “magnify”) the more you start to see pixels, and lose the idea of what you are looking at in the first place. On the other hand, if you are too far away, you won’t have a clear picture as well. So, as you might have guessed, only when you are at the optimum distance, the image is magnified enough and clear.

The same goes for telescopes, they have their Maximum Useful Magnification. To determine the highest theoretical magnification value of a certain telescope, assuming that it has mirrors and lens of the highest quality, and that the sky and atmosphere conditions are ideal, you need to multiply 60*D (aperture in inch) or 2,36*D (aperture in mm). So, for example, a 10-inch aperture telescope has the highest useful magnification of 600x. In that case higher magnifications are going to produce unclear image.

 

Telescope buying guide-Focal length

 

The focal length is the distance the light that enters the telescope, travels from the lens to your eye. In most cases, that is approximately equal to the length of the telescope’s tube, except when you are using a  compound telescope. Because with this type, the light travels back and forth due to more mirrors, and its focal length value is higher than the length of the tube.

Now, as for the magnification, the combination of focal length and different eyepieces, gives you magnifying power. This means, that, for example, if you have a telescope that comes with a 1000mm focal length and you use a 10mm eyepiece, your magnification will be 100x.

Generally, focal length is not that important when choosing a telescope, well, at least not as important as aperture. But  the longer focal length you choose, the bigger will the objects look in the eyepiece. Our advice on this? When you are not sure about the focal length value to choose, always try to find a telescope model that offers  both large focal length, but a large aperture as well.

 

Telescope buying guide – Focal ratio

 

The speed of your telescope’s optical system, is known as the focal ratio or “F”, and is calculated by dividing the focal length with aperture. For example, longer focal lengths of more than f/8, are considered to be slower, while f/6 or lower, are considered to be faster.

Knowing this is important if you plan on trying Astrophotography. Smaller the F value is, more brighter the image will be.

 

Telescope buying guide-Mount type

 

Telescope mounts represent  a mechanical structure, with the purpose of supporting a telescope. They are designed to offer support to telescope’s mass. But to likewise allow you to accurately “aim” the telescope where you want. There are numerous sorts of mounts that had been designed in the last few decades, but all of them can be classified into three main types:

 

Altazimuth

The Altazimuth mount type comes with the simplest design that offers two motions. Horizontal and vertical, thus the name, since it provides altitude, or vertical movement, and horizontal movement (azimuth) – Altitude+Azimuth=Altazimuth. 

Today’s telescopes that come with this type of a mount, usually include computer control as well, or a precise tracking slow-motion  adjustment know. Which is manual, but still gives you smooth movement. In both cases,computerized or manual, these mounts offer you maximum control over your telescope movement.  

 

Dobsonian

The Dobsonian mount, is actually a more modern design of the Altazimuth mount, and was constructed by John Dobson, in the 70s. These types of mounts allow ground mounting and support the weight of  the optical tube that comes with heavy Newtonian Reflectors, all thanks to their heavy platform.

The most important thing about these mounts and the Dobsonian telescopes is that the telescopes themselves actually come with quite large apertures, going from 6 to 20 or more inches.

 

Equatorial

To put it as simple as possible, the equatorial mounts, as their name suggests, offer you the possibility of using your telescope for following the rotation of the night sky, while the Earth rotates. With this type of mount, there are three parameters that you need to set. Adjusting the vertical and horizontal directions, just like with the altazimuth mount, and an additional equatorial alignment adjustment, where alignment of  the Earth’s axis  to the equatorial mount is needed.

This allows you to slowly turn the telescope so that in your field of view, the objects in the sky appear to stand still, regardless of the earth’s rotation. Of course, it takes some time to get used to this type of telescope movement, but once you get the hang of it, your Astrophotography skill level will reach the new height.

 

Telescope buying guide – Accessories

 

Just like with any other type of technological gadgets, telescopes have accessories that allow you to improve your stock model and make it more versatile, whether we are talking about magnification, clarity of the image, or simply helping you identify constellations easier and have a better insight into star charts. Here are the most important accessories for telescopes, you definitely need to consider:

 

Eyepiece

When talking about telescope versatility, swapping your eyepieces is actually the process that makes any telescope versatile, and gives it the ability to be used for different situations and conditions. An eyepiece, is the interchangeable part of the telescope, and the one you actually look through every time you use the telescope.

So, the more eyepieces you have, the more versatile your telescope will be. Now, most telescope packages include one or maybe 2 eyepieces. Usually, the standard package includes a 25mm focal length eyepiece. Because it offers field of view and magnification that are optimized for general viewing.

But, if you want to have a telescope that is versatile and useful for various applications, we suggest starting with  5, 10, 15, 25, and 32mm focal length eyepieces. Later, you can upgrade your collection with other focal lengths, depending on your needs.

Also, you should know that most of these eyepieces are sold as a package, because the market is a competitive place, and the manufacturers want to offer their customers the best deal, which you definitely won’t mind, right?

Furthermore, you should also remember to buy eyepieces that are on pair with your telescope’s quality. This means that, if you have a high-end telescope model, it is a better idea to save up and buy a high-quality eyepiece. So that you can get the best out of your telescope.

 

Barlow lens

This is a very useful accessory, that connects directly to the eyepiece you are using on the telescope and the one that is being used mostly is the 2x Barlow. Now, what does a Barlow lens do? It doubles your eyepiece’s magnifying power. Let’s take a 20mm eyepiece for example. If you are using it with a telescope that has a focal length of 1000mm, your magnification is x50. Right? Well, if you add the mentioned Barlow lens, it will improve the magnification power of your telescope to x100.

Another great feature of the Barlow lenses, is that, besides doubling your eyepiece’s magnification power, it actually doubles your entire collection of eyepieces. For example, if you own 10, 26, and 32mm eyepieces, adding, for example a 2x Barlow lens, would be as if you also have 5, 13, and 16mm focal length eyepieces in your collection. Also, since Barlow lenses are much cheaper than eyepieces, this is a really cost effective way of improving your telescope’s overall performance.  

 

     How to choose it?

For choosing the right one for your telescope, as well as your needs, it is essential that the one you choose have the size of the barrel proper for your eyepiece.  In case you are wondering what barrel size is, it’s simple, it is the diameter of the part of the eyepiece that goes into the focuses, more precisely the tube.

The standard size of the eyepiece barrel goes from 1 to one quarter of an inch. But some eyepieces come with a barrel size of 2 inches, while there are also eyepieces with a size of 0.965 inches, but those are usually found on some really cheap models.  Now, it is imperative that you first determine your eyepiece barrel size, and choose your Barlow lens based on that.  

    How to use it?

When it comes to using a Barlow lens, it is actually extremely simple. All you need to remember is that it goes first into the telescope’s focuser, and then you should attach the eyepiece onto it.

 

Finder

 

When you use your telescope at high or medium power, it displays just a tiny fraction of the entire sky, and, you will agree with us, this makes locating a specific celestial body quite complicated and makes the entire experience frustrating.

Therefore, most people are using a Finder, which, as the name suggest, helps you in locating objects in the sky much easier and faster. The most common finder model you can find is a miniature telescope, that needs to be attached near the main scope’s eyepiece, by using a bracket.

Now, how do finders actually work. The answer is rather simple. Finders come with a low magnification power, therefore, have a much wider field of view, and they also have crosshairs, like the ones found on rifle scopes. This means that, once you properly align the finder with your telescope, finding a certain object will be much easier because, in layman’s terms, what you aim with the finder’s wide-angle view, is what you also aim with the main telescope, only much closer and narrower.

    How to choose it?

When it comes to choosing a finder for yourself, look for models that are high-quality made and reasonably big, and have larger than one inch aperture.

Another way of dealing with this issue is using a reflex sight, which actually projects a ring or rings, or a point of light, on the background sky when looked from behind. This is a popular choice with many astronomy hobbyists, but it has a downside. Because it has no magnification and it’s light-gathering aperture is not better, than your eyeball’s pupil, it limits you to locating only naked-eye objects. But, if you have sky maps that are sufficiently detailed, you can still “jump” from ” naked-eye to deep-sky objects, by staying at the lowest possible power of your main scope.  

             

Kits GOTO

The latest craze in the world of Astronomy hobbyists are the computer-controlled GOTO telescopes and the kits for turning your telescope into a such. They are showing up on the market in bigger and bigger numbers. These kits come with mounts that either have an inbuilt computer that controls the telescope’s movement, or are controlled remotely by an external PC. By adding such a kit to your telescope, you will be able to “zoom in” to any desired object, as long as your computer has it in its database.

When presented like this, one might think that these kits are the solution that take out all the hard work of locating the elusive objects such as asteroids, star clusters, and faint galaxies, star clusters asteroids and that “learning” the sky is not necessary anymore.

However, it is not exactly like that. In reality, these kits are making the entire procedure faster and easier and the overall experience improved, but we are still far away from just taking the entire setup outside, switching it on, and just sitting back and enjoying the ride while the telescope automatically “browses” across the sky, searching for your desired object, or whatever you are looking for.

How they works?

How these kits or systems work, is by needing your input, and that means that you have to enter your viewing site’s geographical location, and add time and date, every time you begin the setup procedure. This allows the computer to calculate the position of the objects you are searching for.

Also, in most cases, you will have to point the tube of your telescope to north or if you are located in the southern hemisphere, to south. Then, start a another alignment procedure, that needs,  two bright stars of which you need to know the positions and names, so that your telescope can sync its coordinate system with the coordinates of the sky above you.

So, as you can see, it is not just a “turn it on and it will do all the work” deal. But after getting used to this routine and perfecting it, it shouldn’t take you long, and then it starts being fun and easy. However, if you are a complete beginner in astronomy, the GOTO kits and all the fancy robotics and the fact that you actually need to know the sky well, might be too frustrating.

But, fear not, since the technology is evolving at a rapid pace, the kits are also evolving, and from recently, most of Go To setups include a GPS system of their own, so at least finding out your exact location and setting up is much easier.

How to choose?

Before making the final decision on the kit you want to purchase, you should know that there’s a problem of how accurately the mechanical parts can actually decipher where the electronics are telling them to point the telescope. The truth is, when it comes to astronomical magnifications, there’s no room r errors, not even the tiniest ones. And, since most manufacturers are looking to save the money on design, and the material and build quality, you should know that if you opt for the cheapest possible kit, it will most definitely not work, no matter how great the electronics are.

So, what do we suggest? Well, if you are a beginner, and you do plan on spending a considerably large amount of money for this hobby, instead of spending it on an electronic GOTO mount, it would be a much better idea to spend it on  larger aperture, traditionally mounted telescope. It will offer you a much better and ”deeper” experience.

                           

Kits for Astrophotography

If you are interested in Astrophotography, especially deep sky Astrophotography, you will need a setup that includes a German equatorial mount, a  telescope (if you already don’t own one), a CCD or DSLR camera,  an autoguiding system, as well as all needed accessories that are needed for running  your camera throughout the night.

The first step a beginner needs to make when building a rig for deep sky Astrophotography, is making sure that he has an equatorial mount. Which is essential for accurate tracking of the night sky.

The next step (for those who don’t yet have a telescope) is choosing a model that is well-suited for Astrophotography, and that it can work with either a CCD camera or a DSLR. There are numerous models available on the market, but not all of them can offer you the results you want. So, for a beginner, we recommend to start with the  Apochromatic refractor telescope, because this type is light in weight, compact, and can deliver breathtaking images of the deep sky.

 

Star chart

Just like in everyday life, when you plan on going on a trip with your car, once you hit the road, you will definitely need a road map, right? This especially goes, if you are planning on driving through territories you never visited before.

The same goes for telescopes as well. The truth is, even the most experienced astronomers use big, highly detailed maps of the sky they can get their hands on.

Now, you are maybe already familiar, or even using the rotating “wheel for the stars”, which makes identifying constellations much easier, and is actually known as the Planisphere. And that is good, because you are familiar with the wider point of view of constellation maps.

But, trying to find, for example, a certain Nebula, by just using the Planisphere, is like trying to find a shoe store in London, while being in the USA, and only using a globe. To be able to find locations worth looking at, you definitely need star charts that are highly detailed.

Furthermore, if you haven’t had contact with star charts so far, but do want to start, the smartest and the easiest way to begin, is by using binoculars. Using binoculars comes with two advantages: the view is right side up, and you have FOW with enough wideness for easily locating the star formations that are naked eye visible. The view you get with binoculars is just like the one you get when using a  good finder.

 

Telescope buying guide – Mobility

 

At the end, the only thing left to say is that, before you make your final telescope decision, you should ask yourself where will you use it? If you plan on using the new telescope in your back yard, then a great big model might be the ideal choice.

However, if you plan on taking your new telescope out, in search of perfect dark-sky locations, so that you can get away from the city’s light pollution and get a much better view, size and weight become very important factors. Also, if you do plan on taking it to dark-sky locations, but not manually, but in a car, for camping stargazing trips, you should keep in mind how much of space will it need, and if it can fit with the rest of your camping gear.

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