First Telescope | Universe Today

Written by Tammy Plotner

Are you ready for your first telescope? There's a few things you might like to take into consideration before you go telescope shopping. Understanding what your skies are like where you will be using your new telescope at is crucial to helping you decide what telescope to choose – just as understanding what type of telescope will work best for you is crucial to enjoying the hobby of amateur astronomy. Let's take a look at a few things you should know before you get your first telescope…

Before You Choose Your First Telescope, Choose Your Observing Site

Your observing site can be as simple as a cozy area in your backyard, the rooftop of your apartment building, or as exciting as a remote location in the countryside. While it would be preferable to have absolutely no light pollution and a perfect horizon in all four cardinal directions – north, south, east and west, it’s not always going to happen. The most important thing is to be comfortable and safe where you are at.

Anyone who has ever been in the countryside on a dark night can tell you exactly where a city is from the dome of light which hovers above it. Astronomers consider this light pollution and if you live in the city, you can see its impact. If we are exposed to even indirect light, our eyes can never fully dilate enough to appreciate, or even see, faint objects, or even stars in the skyglow. While it is sometimes impossible to get away from lights altogether, it is possible to find a shielded area where you are not looking directly into a light – like behind a building or tree. You can even use a dark piece of cloth draped over your head like an old-time photographer! Just remember to stay as far away from light as possible so your eyes can adjust properly. Even if you cannot escape the lights of the city, you can still enjoy some wonderful views of brighter objects such at the Moon and planets.

If you decide to drive away from the city, your best bet is to head south if possible – this will place the skyglow to the north where the least interesting objects are. Usually 10 to 15 miles is enough to find dark skies, but even a shorter distance can suffice. Look for a level area, solid ground, and an unobstructed view towards the area of the sky you’re interested in. If you’re at home and your own skies are reasonably dark, look for a place which is easy to carry your equipment to, as shielded from light as possible, and which has the greatest amount of visible sky. If there is a nearby area you can store your equipment in, such as an unheated garage or storage shed, this is great idea because your equipment will remain close to the outdoor temperature and ready for immediate use. If you can leave it assembled, you’ll find you’ll enjoy it more often because you simply “set it outside the door" instead of going through a full set-up process.

Before You Buy Your First Telescope, Learn To Judge Sky Conditions

While some objects, such as the Moon, planets, double stars and bright clusters are less affected by sky conditions, others are far more sensitive to ambient light, such as faint nebula and galaxies. For that reason, we must try to learn a sense of limiting magnitude. While this sounds like a complicated procedure, it’s nothing more than learning to gauge the dimmest star that you can see unaided after dark adaptation. For the most part, a reasonably dark sky means the magnitude – or brightness – of the dimmest stars you can see unaided is probably near 4 or 5. For example, if you can see the “bow” stars in the constellation of Orion, you are seeing at least magnitude 4. The dimmer the star, the higher the number. If you are seeing little sparkles of light west of the “belt,” you are seeing stars of magnitude 5, and so increasing your limiting magnitude to 5. To help learn your stellar magnitudes, buy an astronomy magazine or borrow an astronomy book from your library.

While it's not entirely important you know limiting magnitude numbers right from the start, it will help you learn through experience what you can see and help you to judge what size telescope will probably work best for you. It would be next to impossible on a moonlit night, or a brightly light city sky to see a faint galaxy – even with a very large telescope! The limiting magnitude is the magnitude of the dimmest star you can see unaided. For example, if you can spot a magnitude 6 star, this means you stand a good chance seeing much fainter objects with smaller optics.

How To Choose Your First Telescope

For the first-time buyer, choosing a telescope means an endless array of styles and price ranges that can sometimes be confusing. Fortunately the choice of design is far less important than a few key elements. The most important thing to remember is light gathering ability. No matter which first telescope you choose you will see the lunar landscape like you never thought possible, details on planets, bright galaxies, nebulae and stunning star clusters. A first telescope can come in a variety of colors, styles, sizes, lengths, and manufacturers, but they will all be only one of three designs: the refractor telescope which uses a series of lenses to gather light, the reflector telescope which uses a mirror, or a catadioptric which uses both.

Before you buy, remember again it is aperture—the diameter of the mirror or lens that collects the light—rather than magnifying power that you are looking for. Any telescope you should consider is one that has interchangeable eyepieces, a good finderscope, a smooth working focuser, a steady, rugged mount and quality optics. All telescopes are capable of magnifying power simply by switching eyepieces. Before you even consider a department store telescope, remember a quality astronomical scope from a reputable dealer doesn’t necessarily cost more! Choosing your first telescope is as individual as choosing your first car. A large family wouldn’t be happy with a compact—while a single person has no real need for extra seating. The same is true with choosing a telescope—choose for your needs. You won’t be satisfied with a small telescope if you want to chase faint galaxies from your country home, but you don’t need a large one to enjoy the Moon from your urban back yard.

If you live in the city, chances are you’ll be happiest with a small refractor or catadioptric to enjoy clean views of the Moon and the planets, as well as single stars. If you live in the suburbs the same holds true, but it just might be dark enough to enjoy the larger aperture that an affordable small reflector can give. If you are going to travel to a dark sky site, portability becomes an issue. The refractor offers a more rugged structure, while the catadioptric offers aperture and compact design. There is also nothing wrong with a reflector for travel—as long as you remember that the more often you subject to it vibration and handling, the more often it will require collimation.

If you live rurally, then you really should consider a mid-to-large aperture reflector. The light grasp and resolution are unparalleled for the amount of money. If you are planning on astrophotography, you will also need to consider a telescope's f-ratio—the focal length divided by the aperture, in millimeters. Those with smaller f-ratios are considered "fast" telescopes—requiring less exposure time. No matter what size, design, or even manufacturer, you select, remember the telescope you will love the most is the one you will use. Choose a first telescope you will feel confident in handling!

Buying Your First Telescope

Unfortunately for most of us, buying a telescope isn’t as easy as heading for the mall. It will require a little bit of homework on your part to discover a reputable dealer for quality telescopes such as Meade Instruments, Celestron or other long-standing companies. Many larger camera shops also deal in astronomical equipment, or you may choose to order a telescope from an on-line dealer. The biggest advantage to finding a local dealer is they will have several telescope types and mounts on display for you to examine hands-on. Explain to the salesperson what you are looking for and ask to try different models to get a “feel” for what you will experience when you are on your own.

There are many on-line dealerships that are also willing to answer questions and offer a wide variety of quality instruments at affordable and competitive prices. Many offer guarantees, as well as service, and should be – for the most part – considered as reputable as a local dealer. Before purchasing a used telescope or one that you bid on… please think twice. There is generally an underlying reason why they are being sold. Very few astronomers ever part with a truly good telescope. If you are able to locate an astronomy club in your area, arrange to visit with them. Club members own a variety of telescopes and are usually quite willing to offer not only their opinions, but a view through many styles of telescopes as well!

By arming yourself with as much prior knowledge as possible, you are well on your way towards a well thought-out and well-planned first telescope!

Filed under: Astronomy