mardi 18 août 2009

Telescopes

Telescopes 101

Buying the right telescope to take your love of astronomy to the next level is a big next step in the development of your passion for the stars. In many ways, it is a big step from someone who is just fooling around with astronomy to a serious student of the science. But you and I both know that there is still another big step after buying a telescope before you really know how to use it.

So it is critically important that you get just the right telescope for where you are and what your star gazing preferences are. To start with, let’s discuss the three major kinds of telescopes and then lay down some “Telescope 101” concepts to increase your chances that you will buy the right thing.

The three primary types of telescopes that the amateur astronomer might buy are the Refractor, the Reflector and the Schmidt Cassegrain telescope. The first two are named for the kind of lens that is used. It is pretty easy to see that the lens is the heart of the telescope so the kind that you will use will determine the success of your use of that telescope.

The refractor lens is the simplest because it uses a convex lens to focus the light on the eyepiece. So the lens bends outwards for this purpose. The refractor telescope’s strength is in viewing planets. The reflector’s strength is in seeing more distant objects and the lens is concave or bends in. It uses mirrors to focus the image that you eventually see. The final type, the Schmidt Cassegrain telescope is the most complex and accomplishes the goals of both but it uses an involved system of mirrors to capture the image you want to see.

So to select just the right kind of telescope, your objectives in using the telescope are important. To really understand the strengths and weaknesses not only of the lenses and telescope design but also in how the telescope performs in various star gazing situations, it is best to do some homework up front and get exposure to the different kinds. So before you make your first purchase…

* Above all, establish a relationship with a reputable telescope shop that employs people who know their stuff. If you buy your telescope at a Wal-Mart or department store, the odds you will get the right thing are remote.

* Pick the brains of the experts. If you are not already active in an astronomy society or club, the sales people at the telescope store will be able to guide you to the active societies in your area. Once you have connections with people who have bought telescopes, you can get advice about what works and what to avoid that is more valid than anything you will get from a web article or a salesperson at Wal-Mart.

* Try before you buy. This is another advantage of going on some field trips with the astronomy club. You can set aside some quality hours with people who know telescopes and have their rigs set up to examine their equipment, learn the key technical aspects, and try them out before you sink money in your own set up.

There are other considerations to factor into your final purchase decision. How mobile must your telescope be? The tripod or other accessory decisions will change significantly with a telescope that will live on your deck versus one that you plan to take to many remote locations. Along those lines, how difficult is the set up and break down? How complex is the telescope and will you have trouble with maintenance? Network to get the answers to these and other questions. If you do your homework like this, you will find just the right telescope for this next big step in the evolution of your passion for astronomy.







The Glossary of Telescopes

When you enter into any new area of science, you almost always find yourself with a baffling new language of technical terms to learn before you can converse with the experts. This is certainly true in astronomy both in terms of terms that refer to the cosmos and terms that describe the tools of the trade, the most prevalent being the telescope. So to get us off of first base, let’s define some of the key terms that pertain to telescopes to help you be able to talk to them more intelligently.

The first area of specialization in telescopes has to do with the types of telescopes people use. The three designs of telescopes that most people use are the Refractor, the Reflector and the Schmidt Cassegrain telescope.

* The refractor telescope uses a convex lens to focus the light on the eyepiece.

* The reflector telescope has a concave lens which means it bends in. It uses mirrors to focus the image that you eventually see.

* The Schmidt Cassegrain telescope uses an involved system of mirrors to capture the image you want to see.

* A binocular telescope uses a set of telescopes mounted and synchronized so your view of the sky is 3-D.

Beyond the basic types, other terms refer to parts of the telescope or to the science behind how telescopes work.

* Collimation is a term for how well tuned the telescope is to give you a good clear image of what you are looking at. You want your telescope to have good collimation so you are not getting a false image of the celestial body.

* Aperture is a fancy word for how big the lens of your telescope is. But it’s an important word because the aperture of the lens is the key to how powerful your telescope is. Magnification has nothing to do with it, its all in the aperture.

* Focuser is the housing that keeps the eyepiece of the telescope, or what you will look through, in place. The focuser has to be stable and in good repair for you to have an image you can rely on.

* Mount and Wedge. Both of these terms refer to the tripod your telescope sits on. The mount is the actual tripod and the wedge is the device that lets you attach the telescope to the mount. The mount and the wedge are there to assist you with a superior viewing session and to keep your expensive telescope safe from a fall.

* An Altazimuth Mount refers to the tripod of the telescope that holds the device in place and makes it useful during a star gazing session. The altazimuth mouth allows the telescope to move both horizontally (which is the azimuth) and vertically. In this way you have full range to look at things close to the horizon or directly overhead.

* Coma has a different meaning than the one we are used to, and that’s a good thing. The coma is the blurry area on the outer rims of your view through the telescope. How big the coma is and to what extent it interferes with your viewing will have is important to the effectiveness of your telesscope.

* Planisphere. A fancy word for a star chart. It is nothing less or more than a detailed map of where everything is in the cosmos and how to find the star you wish to study by keying off of known stars.

* Barlow. This refers to a specialized type of lens that you can buy to enhance the magnification of your telescope.

These are just a few of the basic concepts of telescope operation. We deliberately picked the ones you have to know to discuss telescopes intelligently. But your education into the more complex aspects of astronomy and telescope design and operation will go on for as long as you are a lover of astronomy, which we hope is for the rest of your life.







The Basics of Buying a Telescope

There is a moment in the life of any aspiring astronomer that it is time to buy that first telescope. It’s exciting to think about setting up your own viewing station whether that is on the deck of your home or having a powerful but mobile telescope set up to take to the remove countryside to really get a good shot at some breath taking star gazing.

The last thing we would want to do is to take away any of the “fun” of your hobby of astronomy because the joy of what we do as star gazers is a big part of the appeal. But unlike many other hobbies, ours is a passion of science, of learning and of discovery. And don’t kid yourself, even a hobbyist with a limited telescopic set up can see some amazing things in the stars. So let’s be sure you invest in a solid piece of equipment that you can continue to grow with as your knowledge and ability as an astronomer grows. But how do we do that?

Meet the Geeks.
Now we use the term “telescope geeks” lovingly because any of us who are devoted to our love of astronomy eventually become telescope geeks. And these are the type of people who will know exactly how to evaluate your needs in terms of where you are right now and where you want to go as your hobby grows with you. So if you have not yet associated with a local astronomy club, now is the time to do it.

Start rubbing elbows with people who live and breathe telescopes. Their input is a hundred times more reliable than what a sales brochure or that salesman might have to say because the “telescope geeks” have been where you are, made the mistakes and are eager to help you avoid those same mistakes.

Size Matters
In the world of telescopes, the sales people see, to try to baffle us with all the bells and whistles of their hottest selling model. One of the big check points that is often pushed is the amplification level of the telescope lens. While that is a factor that is worth noting, when it comes to a telescope lens, the old phrase “size matters” is a good guideline.

Just remember that your telescope lens works best when it takes in the most light it can from the object you are viewing. So the wider the diameter of the lens, the better a view you are going to get. So don’t fall for the amplification level only. Carefully evaluate the lens size so you have the right fit for what you want to do.

It Has to Stand on Its Own Feet.
If you are going to set up a permanent telescope station, then you can bolt the unit down so it is well supported. But many of us have to take our telescopes out into the country for optimum use. So the stand has to be strong and flexible so we can set up the telescope on uneven turf but still feel secure that this important and expensive piece of equipment is going to stand on its own without fear of it falling during our observation time.

We already mentioned strong and flexible as evaluation guides for the telescope stand but add in ease of use as well. You have to be able to set your telescope up and break it down quickly and easily when you are on a remote viewing. You may even find yourself setting up or taking down your telescope in the dark or by lantern or flashlight if you are taking advantage of the great star displays in the late night sky that make this hobby so exciting.

These are the basics of what to look for in your new telescope. Finally, make sure the telescope can be enhanced and expanded without having to throw the first unit away and buy something completely new. You want your telescope to grow as your knowledge and skills grow. If your first telescope meets all of these requirements, you are off on the right foot on a long and enjoyable career as an amateur astronomer.






Dude, You’re Getting a Telescope!

You might remember the Dell computer commercials in which a youth reports this exciting news to his friends that they are about to get their new computer by telling them, “Dude, you’re getting a Dell!” It was a cute series but it reflects the excitement young people get about anything new, particularly if it’s a new machine.

So when its time to finally get your children that very first telescope, you want to make sure it’s just the right thing. There are a number of reasons you should put some serious thought into just what this beginner telescope should look like. Perhaps this will be your children’s first experience with a real telescope. They may have a healthy and thriving love of astronomy from your family trips to the country to watch a meteor shower or just to gaze at the stars. And you may have piqued their interest showing them how to enhance the experience with binoculars or even letting them play with your telescope.

But this is a big moment. You want them to “bond” with this first telescope the way you did and catch the excitement of using the power of a telescope to do things with their love of astronomy that they could never do before. The reasons for taking care with your choice are many including…

* A telescope is a big step into the lifelong hobby of astronomy. If they get the wrong thing, frustration could make them lose interest both in the machine and in the field of study.
* Kids have a short attention span. You want this beginner telescope to take them from where they are to the next level while giving them those gratifying moments discovering new things in the stars every time they use it.
* It has to be a hardy piece of equipment. Kids don’t always know how to treat delicate equipment. So the starter telescope should have some good “training wheels” on it.
* It has to be their teacher even when they don’t know they are in school. A good beginner telescope, accompanied by some stimulating documentation that is written just for kids will stimulate their excitement and use it to teach them to work hard to reach new heights in their quest for knowledge about the stars.

A lot about how you go about getting this first telescope will depend on your own expertise in astronomy. If it is your passion and you have developed a pretty sophisticated knowledge about telescopes over the years, you not only are well equipped to make this choice but you will be there to guide them as they begin to use it.

But if you are just encouraging them in a wonderful hobby that you yourself have not been involved with in depth, first of all, congratulations. You are giving them a wonderful gift of not only knowledge but the love of astronomy and the natural wonder of nature. But you also need some help. So here are some quick guidelines.

* Find the astronomy geeks. They are easy to find in hobby shops, astronomy clubs and societies at the local college. They will help you enthusiastically.
* Look at the telescope you are considering through their eyes. It should not be too complex. Don’t get something that will intimidate them.
* Don’t buy a toy. Your kids will know the difference.
* Make sure it can grow and be expanded as their knowledge expands.

If you put some wise consideration into just the right starter telescope, your kids will be as excited they have ever been for a gift. Don’t be surprised if you hear one of them squeal, “Dude, you got a telescope!”



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