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Choosing a telescope: A Beginner’s Guide in 6 Easy Steps


by: OZScopes - The Australian Telescope Experts

For most beginner astronomers finding the right beginner telescope is an extremely daunting task. The world of astronomy is a fascinating place but the process of finding the right telescopes for beginners can be filled with technical jargon, confusing features and a multitude of options. Telescope mechanics can be quite complex and it is not uncommon for new beginners to find themselves purchasing the wrong scope and becoming incredibly disappointed in the process.

To help astronomers, this guide offers a simple resource for explaining what every newcomer needs to know when purchasing their new telescope. To simplify it further, we've split the whole process into 6 easy steps. Just follow them one by one and you can't really go wrong.

STEP 1: Do you know what you want the telescope for? Astronomical or Terrestrial (land viewing)?

It seems like a basic question but you will be surprised at how many people can get this step wrong.

Most individuals purchasing their first telescope are keen to have their purchase provide both excellent views of both land based (terrestrial) and astronomy objects. The truth is, no matter how attractive the thought of an all round telescope is, the common rule is that land based viewing telescopes rarely excel for astronomy, with the same applying to telescopes for sky viewing.

Our recommendation, particularly for beginners, is to decide which type of viewing you will be doing more of. If you are interested in doing more land viewing then you should consider a spotting scope or a pair of binoculars. You can learn more about these different options at our beginner's guide to binoculars and Beginner's guide to spotting scopes pages.

If astronomy is what you're looking for then continue on to step 2.

STEP 2 - Aperture is crucial for telescopes.

The most important feature for any astronomical telescope is its aperture. Aperture refers to the diameter of the telescope's main optical component (consisting of either a lens or mirror). The size of your telescope's aperture determines how much light it can capture. The more light that is captured the more objects you can see in the night sky. Simple right?

More light also means greater clarity in the images you see. Because astronomy is carried out in poor light conditions, having a large aperture means the maximum amount of light is captured for a bright and sharp image.
Before you get too excited about aperture there is a small word of warning. Many people are misled into believing that getting the biggest aperture is the simplest way to choosing the best telescope. What they don't realise is that the larger the aperture the larger the telescopes and big telescopes don't always suit everyone.

Try asking yourself, “Where do I want want to use my new telescope? If the answer is nearby in the backyard then having a large telescope will be great. If you intend to carry the telescope to darker skies away from city lights, you will definitely need something of a smaller aperture but still powerful. A large scope is troublesome while travelling, while a smaller scope in a convenient location may not give as great an image as a larger scope can.

So think about how large you want your telescope to be.

STEP 3 - Magnification is great but not too important

Now this isn't really a step, but more an important concept to understand when choosing your telescope. As said before, aperture is crucially important to your new telescope. Having said that, some will still tell you that magnification (or power as some call it) should determine what telescope to purchase.

Lets get it straight, magnification is important but not a decision making factor.

The magnification of your telescope is determined by the eyepiece you use. Changing magnification just involves swapping your existing eyepiece with one that has a higher magnification. Essentially any telescope can have an infinite range of magnification. So don't get too excited by telescopes that promote a large magnification. It may be possible to get 800x but at that magnification you just highlight air particles between your telescope and the object you're looking at. What would be the point of magnifying an image from a small aperture telescope that doesn't produce a clear image in the first place.

A good analogy would be a television screen. If we go too near the TV (i.e. magnify too much) we end up seeing mere screen pixels. It is only at an optimum distance when the image we see on the TV screen becomes clear.

STEP 4 -Reflector / Refractor / Cassegrain

Ok so we're nearly there. You now understand what is important for a telescope, so lets talk about the three standard telescope types:

1. Refracting Telescope or Refractor

Refracting telescopes are the probably the most common telescope around. They use lenses instead of mirrors and the eyepiece is located at the bottom of the telescope. Their design is similar to binoculars and most spotting scopes. It should be noted that images from refractors are mirror images and can be corrected using an erecting prism. For beginner's this doesn't have a large effect on your viewing experience.

Advantages
  • - Easy to use and consistent due to the simplicity of design.
  • - Excellent for lunar, planetary and binary stargazing especially with larger apertures.
  • - Sealed tube protects optics and reduces image degrading air currents.
  • - Rugged, needs little or no maintenance and its sealed tube protects optics from image degrading.

Disadvantages
  • - Generally have small apertures, typically 3 to 5 inches.
  • - Smaller apertures mean poorer viewing of distant galaxies and nebulae.
  • - Heavier, longer and bulkier than reflector and cassegrain telescopes of equal aperture.
  • - Good-quality refractors cost more per inch of aperture than any other kind of telescope.

2. Reflecting Telescope or Reflector

Reflecting telescopes use a mirror, instead of a lens, and the eyepiece is located at the side of the main tube. You look through an eyepiece on the side of the tube up near the top.

Advantages
  • - Usually have larger apertures which mean excellent viewing of faint deep sky objects (remote galaxies, nebulae and star clusters).
  • - Low in optical irregularities and deliver very bright images.
  • - A reflector costs the least per inch of aperture compared to refractors and catadioptrics since mirrors can be produced at less cost than lenses.

Disadvantages
  • - Generally, not suited for terrestrial applications
  • - The tube is open to the air, which means dust on the optics even if the tube is kept under wraps
  • - Reflectors may require a little more care and maintenance

3. Cassegrain Telescopes or Catadioptric telescope

Catadioptric telescopes or Cassegrain Telescopes, use a combination of mirrors and lenses. These telescopes usually have a nice modern design and have 3" and larger apertures. Two of the popular cassegrain designs are the Schmidt-Cassegrain and Maksutov-Cassegrain.

Advantages

  • - Most versatile type of telescope with excellent lunar, planetary and deep space observing plus terrestrial viewing and photography.
  • - Best near focus capability of any type telescope
  • - First-rate for deep sky observing or astrophotography with fast films or CCD's
  • - Closed tube design reduces image degrading air currents
  • - Compact and durable

Disadvantages
  • - More expensive than reflectors of equal aperture
  • - Its appearance may not be suited to everybody's taste

STEP 5 - A stable mount is always a good thing

Now that you know what type of telescopes are out there, let us discuss an often overlooked but very important aspect - the mountings. A mount is important for stabilising your telescope and determining how easy it is to follow a star while viewing it.

There are two basic telescope mountings:


  • Equatorial Mount
  • AltAzimouth Mounts

An Equatorial mount, simply put, allows users to follow the rotation of the sky as the Earth turns. This is a great help when you're trying to find your way among the stars with a map. These usually cost a bit more but it is highly recommended.

The Altazimuth mounts in contrast have a simpler design, meaning they just swing up, down, left and right. You have to move the scope every so often to follow the stars, moons and planets as the earth turns. An altazimuth mount is both cheaper and lighter for the same degree of stability but it misses out on the ability to easily follow the rotation of the sky when the earth turns.

STEP 6 - Make a Decision based on your budget

Well we've reached the last step. Making a decision on how much to spend. Our advice is to pick the telescope that meets not just your budget but also precise needs and hobbies. Sometimes spending slightly more on a telescope ensures that you get a better scope that will last you for a longer term rather than a cheaper scope that you will replace in a couple of years.

Generally we recommend for customers to be prepared to spend anything from $350 through to $800 for a decent starter scope. This gives you a great starter scope that will have you enjoying clear views of the night sky and exploring the different space objects that colour the universe above us.

If you want some recommendations look below. These are awesome starter scopes that customers love and just keep using again and again. Alternatively you can feel free to give us a ring on (03) 9780 1888 for more personalised advice.

Happy Scoping
The OZScopes Team

OZScopes - Highly Recommended Telescopes for Beginners