Tuesday, December 05 2006 @ 10:59 PM CST
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.
The "COST" of a Telescope
|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|
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.
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.