Telescope Buying Guide: How To Choose Your First Telescope

Once you have got to grips with all the star charts, maps and other technical information you need to become a fully equipped amateur stargazer, the next question is, which telescope to buy? There are so many different models out there, with different specifications, performances and specialised gadgetry, that it can be a little confusing to know what it is you should be spending your money on.

Thanks to Anacortes Telescope in Anacortes, Washington, we have put together an handy telescope buying guide to help you make one of the most important decisions of your astronomy career. Carry on reading to get to grips with a few of the basics…

Aperture

This is another name for the light-gathering abilities of a telescope, and it’s actually one of its most important features. The ability of a telescope to pull all of the available light from the surroundings is what makes those fuzzy images that you are looking at brighter and more visible.

Increasing the magnification does not necessarily create a better view, because you are not only magnifying what you are trying to look for, but also the layers of atmosphere your telescope has to look through in order for you to see the image.

A smaller telescope is more suited for viewing the stars and planets closer to the earth, while a much larger Dobsonian is better for getting good views of the really deep space objects.

Focal Length and Ratio

Focal length is the distance taken by the lens or mirror in order to be able to focus starlight. Focal length decides the length of your telescope, and the magnification given by each eyepiece (the magnification is the focal length of the telescope divided by the focal length of the eyepiece, in case you were wondering).

The focal ratio is the focal length of the tube, divided by the diameter of the lens or mirror. Helpfully for you, these numbers are printed on the tube of every telescope!

One useful tip to bear in mind is that the lower the focal ratio, the harder it is for the telescope to give you really good magnification. These lower focal ratio scopes are ideal for daytime use, or for getting some really good shots of our own planet, but not so great for deep space.

Refracting Telescopes

These are the most well-known type of telescope. Refractors collect and focus light in the lens at the end of the tube, and are great for beginners as they don’t require manual adjustments. They are perfect for daytime viewing, for observing the moon and planets, and are especially suitable for use in cities, as they can help reduce the effects of light pollution.

Refracting telescopes tend to be cheaper than some of their peers, making them a great choice for those who wish to get into stargazing but have budget concerns. That being said, there are levels of pricing within the refracting range, based on the type of glass used in the lens itself.

The three levels are Achromatic, ED and Apochromatic. The more basic lens, the Achromatic, can allow a little colour distortion, which can be distracting, the ED has darker contrast and less of the colour distortion, while the really high end Apochromatic lenses offer good contrast with none of the colour distortion.

Reflecting Telescopes

This is a type of telescope which uses a concave mirror as opposed to a convex glass. The light bounces off two mirrors inside the telescope, bringing it to your eye so that you can make the very most of all available light.

These scopes are ideal for getting into the really deepest, darkest space viewing such as globular clusters and supernovas. They are not suitable for daytime terrestrial viewing however, as everything you try to look at would be upside down and back to front!

Compound Telescopes

This type of scope, also called a Shmidt Cassegrain telescope (SCT), uses both a lens and a mirror. The mirror gathers all the available light, while the lens corrects the spherical shape of the mirror and brings the light into a tighter focus.

These scopes have the advantage of having a long focal length while being more compact and easy to transport, making them ideal for camping trips or stargazing excursions. They are not great for daytime use, but the smaller versions can just about give some good shots.

What To Avoid

It’s all very well deciding what you want to get, but it’s also worth taking a look at what you really DON’T want! The telescopes that claim huge magnification such as 200x, 300x or even 400x, should be avoided as telescopes that you can buy in shops just don’t have this sort of magnification power.

Also look out for the tripod; you don’t want a wobbly, rickety tripod that is going to shake around as you are viewing.

And don’t be distracted by pretty pictures! Images on the box will have come from stock photographs; you won’t be able to see a huge vision of Saturn with any telescope – the difference is in the amount of detail that you can see.

Finder Scopes

The sky is really, really big. Because of this, and the fact that you only look at a tiny piece of it through your telescope eyepiece, it can be hard to find what you are actually looking for.

A finder scope is a little scope on the side of the main telescope that has a much wider field of view, and sometimes cross hairs to help you pinpoint your target.

Some scopes have a right angled viewfinder that can really save your neck, especially if you are shorter than the average basketball player! Still others have a “red dot” finder scope, which makes finding your perfect shot even easier.

Telescope Mounts

A good mount is almost as important as a good telescope. Having a wobbly, shaky mount can adversely affect your stargazing experience, and could even put you off completely. There are two types of mount – the Alt-Azimuth and the Equatorial (more about Equatorial later).

Alt stands for altitude, Azimuth for left and right – it’s a pretty simple concept; a good steady mount that can move in all directions, with a tensioning dial so that you can adjust the tension to suit you. This type of mount can be used for both daytime terrestrial use and astronomy.

a. Dobsonian Mount

This is a type of Alt-Azimuth mount, that holds a reflector telescope on a sturdy base and allows a full sweep of the sky. It is a low cost mount that works for a variety of different sized telescopes, and can be easily packed up and transported for stargazing trips. Larger Dob mounts have truss tubes, which are surprisingly easy to break down and pack up.

b. Equatorial Mounts

An equatorial mount compensates for the Earth’s rotation by the movement of a single axis. They are important for observers who wish to keep a single spot fixed in their field of view, and absolutely essential for astrophotography – but they are not so great for daytime or terrestrial viewing. They are stable and adjustable, and easy to use. Some equatorial mounts have a motor drive, which, once activated, will automatically follow a fixed point across the sky.

c. GoTo Mounts

Now this is some serious gadgetry. You can select an object from a catalogue of thousands, click on it, and your telescope will automatically track to that very thing. These mounts do require a bit of setting up – you will have to enter your time, date and longitude, or align your scope with three bright stars so that the telescope knows where it is in the world, but apart from that this mount is technology at its finest. They are portable and lightweight, making them convenient for stargazing out and about.

Solar Filters

Although the sun is our nearest star, for obvious reasons it cannot be viewed through a standard telescope – unless you have a solar filter. With one of these you can see a fascinating amount of detail on the surface of the sun, from sunspots to solar granulation, and even solar flares.

The White Light filter will change the colour of the sun to a whitish blue light, while the H-Alpha filter will show more of the granulation, fine filaments and flares of the sun.

It is actually more cost effective to buy a scope that is dedicated to looking at the sun than it is to try to adapt an existing scope with filters – but they can be a fun addition to your stargazing arsenal.

Eyepieces

Eyepieces are key for a good view of the night sky. They come in two sizes – 1.25″ and 2″. The larger circumference lets in more light and can bring better definition to dim fuzzies, while the smaller size allows for clearer, more high definition shots of the moon and nearby planets. You don’t have to choose one or the other; you will be able to interchange between the two with a diagonal adaptor.

Your telescope will probably come with one or two eyepieces, but as they are one of the most important parts of a good telescope, as any telescope buying guide will tell you, you might very well find yourself wanting to upgrade.

Barlow Lenses

A Barlow lens is a clever accessory with which you can increase the magnification of your eyepieces. It allows you to get a higher magnification with a longer focal length eyepiece, which can help increase the distance your eye needs to be from the eyepiece, thus giving better eye relief.

Barlow lenses can be pricey, but worth it as they can effectively double the number of eyepieces you currently own.

A Bino-Viewer is another type of lens, similar in shape to a pair of binoculars, which allows you to use both eyes to look into your telescope. It’s great for closer objects, but for the deep space viewing a single eyepiece is better, as more of the light is focused and you get a much clearer picture.

Practical Accessories

As well as the telescope buying guide itself, it is handy to look into some extra accessories that might make your life that little bit easier:

  • Scopes with electronics, such as the GoTo mounts, run off battieries which could run out in the middle of a crucial shot. A power source is therefore an important extra accessory.
  • If you are using a refractor or an SCT, you may find that dew collects on the lens, making it impossible to see properly. A felt-lined dew catcher is your saving grace!
  • You can also buy different coloured filters which attach onto the eyepiece, and will bring out different characteristics of the planets you are observing.
  • A neutral density filter, a bit like putting on a pair of sunglasses, will remove some of the light, therefore allowing you to see in greater detail.
  • A red torch is very useful for when you want to see your equipment but don’t want to allow artificial light to ruin your night vision.
  • A planisphere will show you where you are looking in the sky, and give you a reference of where to point your telescope.

Personal Planetariums

These new gadgets are great for learning a bit more about the night sky. You centre an object in the viewfinder, press a button, and you will instantly be told information about that particular object. You can also enter the name of something you want to see and the device will help you to find that object. Stars, deep space objects – you name it, a personal planetarium will find it! Most planetariums have a headphone point so you can plug in and listen to information about what you are looking at.

Final Tips

Although getting into astronomy can seem daunting and confusing, remember that you are not alone. There are huge resources out there, like this telescope buying guide, that will help you find your way. You will also find invaluable websites and forums that you can use to get information and make friends, and local clubs are also great for this. Don’t get frustrated or confused on your own, find others who can help you on your journey. And remember to have fun!

Leave a Reply

TELESCOPES CHRISTMAS DEALS (1st - 21st December)SEE ALL DEALS