Archive for the ‘Telescopes’ Category

Build a Dobsonian Telescope

Wednesday, June 16th, 2010

Building a do-it-yourself telescope is an eventful project and for the astronomer it can bring hours of enjoyment once completed.  Creating the telescope can be complicated or simple, depending on how in-depth you wish to make the project. The most common do-it-yourself telescopes are refractors made by Boy Scouts or in school in physics class, but this project can be as big as your imagination allows.  Building a Dobsonian telescope can save you up to half off of retail value, but depending on the size desired this project can take up days or even weeks to complete.

Materials and Tools Needed

Mirrors manufactured exclusively for telescopes can be purchased new or used; and can also be obtained through a telescope company’s website if a local dealer is not available.  While there, also pick out a chrome-plated eyepiece that suits your taste.  A tube, preferably made from cardboard and obtainable from construction companies, is also necessary and it should match the mirror size in order for the project come out correctly.  You will also need some exterior grade plywood, paint, PVC coupling, a wooden dowel, a mailing tube, leather scrap (a belt also works), Masonite, Teflon, glue, scrap cardboard, and a variety of screws, nuts, tacks, and bolts.    

The required tools are a hammer, a saw, a drill, a tape measure, a compass, screwdrivers, a nail set, a crescent wrench, an awl, a hole-cutter, and a carpenter’s framing square.

The Construction Process

1)      Start off building the telescope by scouring the tube down and painting it. Acrylic garage floor paint will adhere to the tube and provide some water resistance for those that enjoy star gazing outside.

2)      Construct a tube box, or Rocker box, with the plywood, ensuring the box is perfectly square. Attach the main bearing to the bottom of the Rocker Box using countersunk screws.

3)      Create three flawlessly round circles out of wood, cutting the core out of two. Attach the three circles together with glue and clamp them. This will serve as the base of the telescope.

4)      Spray paint the interior of the tube intended for use as the scope. Create a spider out of thin wood slats and a dowel. Glue the mirror right onto the spider with RVC.

5)      Create a cell using wood and steel fittings.

6)      Fit the mirror into the cell and secure with six metal brackets to ensure stability.

7)      Situate the Rocker Box in position where the telescope is going to reside, and carefully attach the tube to the Rocker Box. 

8)      Make the necessary adjustments to the alignment. 

Alignment may need to be done several times in order to get the best results after the telescope is assembled, but once honed in your do-it-yourself one can perform just as nicely, if not better than store bought models.  Once the telescope is functioning properly, the builder can pat themselves on the back, enjoy the stars, moon, and planets and bathe in a distinct feeling of self-accomplishment.

Beginner Telescope

Wednesday, June 16th, 2010

Gazing at the darkened sky, speckled with stars and moons and planets through a telescope opens up the imagination for skilled astronomers. For a person that has never used a telescope before it may sound difficult to do. For the beginner, maneuvering an instrument may seem tricky and the technology might appear intimidating because of the complexity of the tasks involved. On the contrary, there are telescopes made simple enough for even the beginner astronomer with simple adjustments yet very solid functionality.

There are a myriad of different telescopes available on the market for novice stargazers; they fall under the classifications of refractors, reflectors, and compound telescopes. Coming to a decision as to which telescope is right for the aspiring astronomer will depend on their overall viewing expectations.  Although price is always a factor to some degree while seeking the perfect beginner’s telescope, other options to consider like size and portability will also directly affect the amount of enjoyment obtainable from the model.

The price of anything nowadays is usually a deciding factor in any purchasing situation because of the current economy. Telescopes can range from the inexpensive children’s type telescope that provides only basic views of the sky to the mammoth telescope NASA uses to view distant galaxies in perfect detail, named the Hubble Space telescope. Purchasing a telescope from either end of the price spectrum can ultimately leave the consumer frustrated or disappointed if their skill level does not match the complexities of the product. The more expensive telescopes have a tendency to be more complicated and manufactured for use by the accomplished astronomer, leaving the beginner perplexed due to the advanced options. The expected price of a telescope to start exploring the stars with ranges from $200 to $600; however, used models can often be found at a fraction of that price.

Due to the fact that telescope manufacturers promote their telescopes on the market according to the magnification, people assume that magnification is the most important factor. This cannot be further from the truth. The size of the objective, or the lens, is the primary factor in producing the clearest images. The power of the objective mixed with the focus of the magnification produces the image to the eye. Most skilled astronomers normally work with low magnification to view their favorite spots in the sky because the image actually appears clearer than at a high magnification. For the beginning astronomer, in fact, a magnification between 30x and 50x and an objective between four and six inches is more than enough viewing power.

If the telescope will be used specifically for indoor viewing and moving the telescope to different places is not an option, portability should not be a factor. Refractor telescopes are larger size telescopes, characterized by their use of lenses for an objective. For the astronomer wishing to create the perfect experience by relocating the telescope outside, size and portability will definitely need to be taken into consideration before the model is purchased. Reflector telescopes, characterized by the use of mirrors instead of lenses, are a smaller, more portable version of the telescope and they normally work better for the aspiring stargazer who wishes to view the sky from multiple locations.

The beginner will also want to stay away from the computerized telescopes until they acquire a grasp of the sky and its expansive map. These telescopes require the user to input where objects are in the sky in order to function, and the novice astronomer will not have readily memorized this information. As a beginner, it will be more important to learn the map of the sky with the telescope, instead of learning the telescope and the map separately.


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