Q: What Telescope Should I Buy?

Tuesday, December 05 2006 @ 11:59 pm EST

Contributed by: bobmoody

One of the most asked questions that AOAS members, or any amateur astronomer faces is, "What kind of telescope should I buy?" This time of year we hear it more often. I'll try to give you some ideas about how you can help steer someone in the right direction the next time you hear this question.

Sometimes, asking questions can be most helpful in trying to assist someone in making a choice for a telescope. Ask them some basic questions about, 1) How much they want to spend? 2) What they want to see with a telescope? 3) Where will they use their telescope? And 4) Do they have any restrictions on how much they can lift or carry? These are among the most important questions that will help them make the right choice. Its all about which telescope they'll use most often. They won't be happy with any telescope that they don't, or can’t, use regularly.

Small refractor telescopes such as this is what to watch out for at the mega-department stores. In general, the optical glass that forms the image in these telescopes is of sufficient quality to give acceptable images, but the wobbly mounts and the inferior eyepieces supplied with these type of telescope is ALWAYS the thing that does them in. FOREGROUND: Franzie, 1997-2005;Coleman Chief of Security - 2003-2005
The "COST" of a Telescope

Some telescopes can cost a small fortune. These are NOT for the beginner. Many amateur astronomers prefer to influence a beginner to first learn the sky, and begin their star gazing adventures with a pair of binoculars. I have sometimes urged people to first attend several astronomy club star parties, where they can look at objects through club members telescopes and then decide if a telescope is right for them. That's also good advice, but assuming you're going to buy a telescope for yourself or someone special, here are my thoughts and advice for you.

A basic entry-level telescope will run from about $210 and as much as $500 dependent upon an individual’s budget. You shouldn't invest too much early on until you have some idea of whether you like the hobby of amateur astronomy enough to become more deeply involved. But remember.....to get the most out of whatever telescope you may buy, you'll want to start learning the sky anyway in order to locate the telescopic tidbits dwelling there.

These dollar amounts will give the buyer a choice of either a small refractor on a good mount, a small to medium-sized reflector on a simple-yet-sturdy Dobsonian mount (see my story about John Dobson under Topics: Telescopes), or a small reflector on an equatorial mount. Here’s where a little bit of “Telescopes 101” can come in handy.

Telescope Basics

Refractors, reflectors, Dobsonian mounts, equatorial mounts, and when you really think about it, just what exactly is a small or medium-sized telescope, anyway? Well, whether it’s a refractor or a reflector, the main optical component for all telescopes is called the “objective”, and the objective can be either a lens, if a refractor, or a mirror if a reflector. There is also a type of telescope which utilizes both lenses AND mirrors, and these are called catadioptrics, or compound telescopes. [See an image of one by clicking "read more" below]
A home-made 80mm f/13 refractor. AOAS member Margaret Brogley asked me to help her restore this telescope built by her brother in the mid-1950's. I built the wooden mount which gave it the stability it needed to work well. Wobbly mounts are a frequent problem found in smaller refractor telescopes.

A small refractor is in the 70mm to 90mm range, or for the metrically challenged, a 2.7” to 3.5” diameter of the main lens. For a reflector, a small size is typically a 4.5” or a 6”, while an 8”mirror can be considered by some to be medium-sized.

Size Really Matters!

Never be lured into a situation of buying a refractor telescope at a department store. I tell everyone the same thing, “NEVER buy a telescope based on the “Mag Factor” ….magnification is NOT what gives good images. The size of the objective and its quality of craftsmanship are what really count the most. A Wally-World Rosco telescope advertising 650x power isn’t even worth a second glance, except maybe as an example of what you don’t want to buy.

Telescopic Targets

There are close objects within our solar system, the moon, planets, comets and asteroids, all of which refractors work very well on, and then there are the galaxies, nebulae, and thousands more objects in the deep-sky available for viewing with 4.5” to 8” (and larger) telescopes.

Click read more for more targets, more helpful suggestions about choosing telescopes, and for a group of links to some telescope manufacturers and dealers.

The simple and super-sturdy Dobsonian mount makes this AOAS-owned 13.1" f/4.5 reflector a great telescope available for ALL paid members to use here at Coleman Observatory.
As a general rule, refractors work best on planetary and lunar objects. Reflectors work best on dimmer deep-sky objects. While this idea was more accurate 30 years ago, the reflecting telescopes of today can easily be as good as any refractor, and that extra size allows them to provide much better views of those dim “fuzzies” as well. Smaller refractor lenses just can’t go as far to deliver very good views of dimmer galaxies and/or nebulae. Some amateur astronomers have one good telescope of each type.

Where Can I View From?

Setting up your telescope in your yard or driveway is something many amateur astronomers do on a regular basis. That’s okay to a point. It isn’t as good an idea if you’re viewing from within a city’s light-polluted boundaries, but if this allows you to get in more “eyepiece time”, then that’s a good thing. USE whatever telescope you decide to buy as often as you can.

The great part about simply setting up in your own yard or driveway is that the neighbors are bound to take notice very quickly. Those neighbors you already speak to will likely be curious enough to come on over and ask what your “cannon” is aimed at. This isn’t as silly as it sounds….I’ve had several people ask me what I was setting up, and yes, a couple have thought my telescope was a cannon or a rocket launcher. If there are lots of neighbors in all directions, you might also assure them all that you aren’t “spying” on them.

Here is our AOAS-owned CETUS telescope. This is a 14" f/11 Schmidt-Cassegrain optical system. This is the Catadioptric type of telescopes that use both lenses AND mirrors to form the image.


Another good thing about setting up at your home is that the curious neighbors just may want to start the hobby themselves. It can be addicting to see the Rings of Saturn, the craters of our Moon, and so many other objects that they’ve never seen before. You’ll become known as the local astronomy wizard in short order, and then they’re asking you what telescope they should buy. It’s a snowball effect and learning along with a friend helps both learn more, faster.

And then there’s that opportunity that arises when you’ve packed up your telescope and accessories and traveled several miles out of town to a true dark-sky site to observe from. Suddenly, everything you had begun to see and become familiar with at home is now revealed in incredible detail and clarity. It’s almost as good as having a new telescope that’s about one-size bigger. The constellations you’ve just learned and have become recognizable to you are wiped out by hundreds more tiny dim stars that were there all along, but the sky-glow from within the city had always been blocking their light. It can be almost unnerving when this happens for the first time. But the memories you take away from such a moving experience as viewing from a really dark site will last a lifetime. Now you’ve seen why everyone says that it’s worth the expense and time needed to get out to those places as often as they can. You are now hooked, totally and completely, and you’ll never again see the sky in quite the same way. Such is the way we fall in love with our hobby of amateur astronomy.

Its Too Heavy

Never forget the question regarding whether the new telescope buyer will be able to comfortably carry and setup the components of their new telescope.
Don't forget about the accessories that are also needed to get all that you can out of your telescope. Extra eyepieces, filters, finderscopes, there are many different things that give a telescope user a more enjoyable experience.
You don't need a week or a month resting up from lifting some piece of your telescope that caused a slipped disk or muscle strain. That makes anyone discouraged enough to give up. Again, it depends on how often someone will use their telescope that helps determine whether they’ll enjoy themselves or not. Don’t buy a telescope that requires two to setup, unless two people will always be available to set it up. One-size smaller telescope will make the difference in how much pleasure is experienced from frequent use. The difference in what you’ll see between a 6” reflector compared to what’s seen through an 8” is a fairly small amount of details. You’ll only easily be able to see the differences in the views between a 6” and an 8” after a few years of observing experience.

What About Accessories?

Most telescopes come with only one eyepiece. The eyepiece is the single most important accessory for telescope users. I usually advise that an EXTRA amount equal to 30% to 50% of the total cost of the telescope you choose be spent on a complete set of accessories. This does NOT have to be all bought at the time the telescope is purchased, but one extra eyepiece and a Barlow lens is encouraged at the time of the initial purchase. Every eyepiece gives a different power of magnification for each individual telescope.

Everyone learns early on that some objects look much better with a little more magnification. Other objects want a wider field-of-view and a very LOW power of magnification. Experience will be the most helpful tool in choosing which accessories should be bought, and you can soon find out more about your choices for accessories in our AOAS "Telescopes 101" page, slated for posting around January 1, 2007.

Summing It All Up

There is no perfect telescope size, or type, for everyone. That’s one reason why there are so many sizes and types available today. My favorite may not be your favorite, and many amateurs have more than one telescope too, as I mentioned above. Some will actually move to a smaller town or even to an area farther away from ALL intrusive lighting away from any surrounding towns just to be closer to an ideal observing site. You simply have to understand that this is how powerfully this hobby overtakes some folk’s lives. All of what they’ll do is done for more opportunities to use their telescope more often……and isn’t that what I already said was the most important factor in deciding what telescope one should buy in the first place? If you can help someone buy the telescope that they’ll USE most often, they’ll forever thank you for helping them find the “perfect” telescope.


Some very helpful websites and links!

My TOP Pick; The all-around favorite, a 6"f/8 Dobsonian from several different makers for about $250

The "next step up", an 8"f/6 Dobsonian for about $350

My TOP Refractor Pick Konusmotor 90 low-cost 90mm f/11.1, two eyepieces (17mm & 10mm) AND a 9v. battery-driven R.A. motor available from several American dealers, like Astronomics $209.00

Recommended Dealers

Astronomics.com

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