Amateur Astronomy:

Amateur astronomy for me has been an outlet, a way to relax when the world is asleep at least in my neck of the woods. The first spark came with the launch of Voyager II. I really hung on every event that mission produced. Just think, before Voyager, all we had was ground based telescope images of the far planets. Thanks to a little probe from Earth, we now have stunning images of worlds so strange and beautiful. Astronomy is a great hobby to share with others or just by yourself. Just get out and do some observing.

Now is the time to discuss some telescope stuff. First of all, as you begin to yearn for that first scope, many small scope makers will be out to get your money. Yes yours... The scopes in question advertise extreme magnifications (560x or more). Please don't be fooled by these claims. First of all the image at those powers are useless. There is not enough light entering the scope or your eye to do any good at all. Second and very important is the mounts. These tripods and hardware are shaky and often hard to use at night. I have seen these mounts strip out threads and such and render themselves useless. Please if nothing else, don't be fooled by the advertising. If you really want a low budget instrument, get a good pair of 7x35 or 10x50 binoculars. This is the first instrument I ever used and still use extensively today. If possible try and find a local amateur astronomer for more information on telescopes. I stress this opinion because to many people buy these dime store scopes and find out that they are not what they seem and they end up in closet or in the twilight zone(under the bed). Strange things live there you know!! If you want some more detailed no nonsense info I will gladly e-mail you any help I can give you. I will be posting more here later.

I have built 5 telescopes so far and own a Celestron 8" SCT in my observatory. I call my observatory "Rabbit's Run Observatory". There are lots of rabbits out here. This image below is my front line scope. It is a 10" f4.25 truss tube Newtonian Reflector. It is a Rich Field Telescope because of it's short focal length. It may look hard to build but it really wasn't.

"Equipment talk and other perhaps useful stuff"

I will get started by investigating the different types of scopes that most amateur astronomers use. I will highlight the various points of interest for each type.

I will not get over technical as lots of folks tend to do. As long as a scope gives you pleasing images and is easy to use. Besides money, this should be first in your mind.

There are three main types of telescopes that the amateur astronomer uses. The refractor, reflector and Schmidt-Cassegrain. Of course you will see variations on these. But for our project here, we will deal with these three basic types.

The Refractor:

This type of scope was probably the first scope ever invented. Many credit Galileo with it's invention however some will dispute this fact. A Dutch gentleman by the name of Hans Lipershay first came up with this design. A refractor uses a compound lens system in the front end of the scope. The cost of grinding these lenses is what makes a refractor so expensive. Of course you could go buy a dime store refractor and be real disappointed. Because when you view with a cheap one and a good quality scope you will soon understand. Normally, a refractor has a long focal length which makes it a dynamite scope for planet viewing and deep sky photography. The image produced by this type of telescope is an upside down image. If you add a mirror diagonal, it will be upside down and mirrored.

Pros:

  1. Exceptional images of planets and double stars and deep sky objects.
  2. Great scope for photography.
  3. Portability - Due to the small aperture involved, this type is relatively easy to move about.
Cons:
  1. Price: The price per aperture for this type is the most expensive.
  2. Apertures range from 4" to 7" - A Meade 7" f/9 ED Apochromatic runs in the magazines for $5995.00
  3. You can shop around for a better price, but for most of us budget star gazers this is somewhat out of our range.
  4. Setup: Setting up any type of scope that will track the stars requires care and time. Especially for photography. This may present a problem for the folks who are not mechanically inclined.

The Reflector:

We now come to the telescope that is probably the most popular. Originally invented by Sir Isaac Newton, this scope uses two optical mirrors. A primary and a smaller secondary mirror. As you scan the astronomy mags, you will see these referred to as "Dobsonian". A man by the name of John Dobson came up with a unique design for the mount. It's ease of construction and portability make this scope a real pleasure to setup and use. The optical design has remained unchanged since Newton's time. A reflector will yield an upside down image.

Pros:

     
  1. Aperture: Dollar for dollar this scope will give you the largest aperture for your money than any other scope available. They range from 4" up 36" and higher if you so desire. However this can be a double edged sword. The larger the aperture the harder it will be to move about. I have seen some 36" Dobs at the Texas Star Party and I'm here to tell you they are a monster. Consider this when making the size choice.
  2. Mounting: The mount for this type scope was originated by John Dobson of the San Francisco Sidewalk Astronomers. A very efficient design allowing ease of use and mobility. Once again size will become an issue in larger sizes. Meade, Celestron and Orion Telescopes all manufacture Dobsonian scopes ranging from 6" to 16" models which were rated well in a Sky & Telescope test. There are other companies that make Dobs, you can shop around and see what you can find.
Cons:
     
  1. Optical alignment: Probably the biggest draw back for Newtonians is the fact that they require constant adjustments when scope is transported about. The primary mirror is held in a mirror cell at the back end of the scope. This mirror is the one most affected by movement. Optical alignment can be very tricky at times without the proper equipment or know how.
  2. Optical surfaces: Due to the fact that the mirror surfaces are exposed to the elements, they require frequent cleanings. Dust and grime accumulate over time. This requires careful cleaning making sure not to damage surface coatings. Also, over time the optical coating will degrade to a point that complete mirror resurfacing is required.
  3. Optical components: Main mirrors tend to be heavy with increase in size. Also the size of the secondary mirror effects how much light actually reaches the primary mirror. This is called "secondary obstruction". This large obstruction reduces the available light and therefore reduces image brightness and contrast.

The Schmidt-Cassagrain

This scope has gained increased popularity over the last few years as the price has come down to a level that amateurs can afford. This scope ranges in the 8" to 16" apertures. It is a closed tube design with a multiple optical component system. In simple English, it has three optical parts. First, the corrector plate then the primary mirror and finally the secondary. This particular design allows for a short tube with a long focal length. This arrangement allows for greater portability, a most important factor for us amateurs with suspect backs. An SCT will give you an upside down and mirrored image because of the primary, the secondary and a mirror diagonal.

Pros:

  1. Design: Compact design allows for large aperture in a shorter tube. 8" & 10" sizes are the most popular.
  2. Astrophotography: This type of scope is well suited for astrophotography. My amateurs use them for CCD work as well. A nice all around scope.
  3. Mounts: The mounts used are primarily the fork design. Some still use an equatorial mount. These type mounts allow for easy tracking of objects in the sky and some also come with optional deep sky databases that allow the observer to "GOTO" the desired object.
Cons:
  1. Setup: Setting up a fork mounted SCT can be a trying experience until you get the hang of it. Even an equatorial is at times a real test of patience. In order to use the tracking capability you must polar align the scope. Each type uses slightly different methods for this. For the very entry level beginner, polar alignment can be a complicated ordeal.
  2. Optics: Though the optics are enclosed in a tube, the biggest drawback of the SCT is that the front corrector plate is extremely susceptible to condensation or "dewing up". Normally owners of SCTs carry ordinary hair dryers with them to dry the plate off at the first sign of dew. Now a system is available called the Kendrick Anti-dew System. This system uses devices to attach to different places on the scope such as: corrector plates, eyepieces, telrads and cameras. They even make laptop heaters now. Many a night's observing has been halted by the dreaded "dew".
In this section I have touched briefly on the more common points of each design. I realize that those technophiles out there will most likely be able to come up with pages more of tech stuff that for the lay person will do nothing but confuse them. The best advise I can offer at this point is that you go out and find some amateur observers near you and ask lots of questions. Look at their scopes and see how they work. Whatever you do, make a good educated purchase of that scope you have always wanted. You will not regret the time invested in a little research. Hopefully the information I have provided here will be a good starting place.