Telescopes - An Overview

Getting your first telescope

Once you are able to identify the most common objects in the night sky with your naked eye and with binoculars, it is time to get you first telescope. This is an important step in your road to becoming an amateur astronomer.

The telescope will help you look further into the night sky. Telescopes can magnify distant objects which cannot be seen with the naked eye or even with a binocular.
When you are getting your first telescope, it is better to invest more and get a good quality one. There are many professional telescopes. A telescope with a big aperture will have greater clarity and will cost more. It will also be more difficult to handle as it would be heavy.

All beginner telescopes today have in built computer tracking systems. The user will have to enter the name of the object and the telescopes automatically aligns itself to it. This helps the beginner traverse the night sky easily.

It is also necessary to get a good tripod with the telescope to get steady images.

Check out this Telescope buying Guide.
http://www.space.com/15693-telescopes-beginners-telescope-reviews-buying-guide.html

Reflecting Telescopes – An Overview

The Reflecting Telescope works by allowing light from the distant object to fall on a mirror in the rear of the telescope. This light is reflected to another mirror which is located at the top of the telescopic tube. This mirror directs the image to the viewer.

The reflecting telescope is generally credited to Sir Isaac newton. Reflecting telescopes are also known as Newtonian Telescopes.

Reflecting telescopes are widely used in professional astronomy. They are small in size for the same magnification when compared to the refracting telescope. They do not suffer from chromatic aberration as the refracting telescope.

The downside is that the many components of the optical system such as mirrors and lenses can get out of alignment. Since, the reflecting tube is open from one end, there are chances for moisture and dust to enter.

The reflecting telescope may be more difficult for children to handle.

Refracting Telescopes – An Overview

Refractor Telescopes are probably the oldest type of telescopes. They are also extremely common. This is because of the simplicity of construction. The telescope consists of a hollow tube with lenses which refract the light. This produces the magnification of the distant object.

Refracting telescopes are also known as dioptric telescope. Refractors are also cheaper than other types of telescopes. You will find them in hobby stores as well as in your neighbourhood departmental store. These telescopes are lightweight and are easier to care for and maintain. For the amateur astronomer, this is often the first telescope.

The downside of these telescopes is that they get very heavy for larger apertures. Hence, at higher magnification required in professional astronomy, they are not much used. Besides, there is the problem of secondary colour (chromatic aberration). The lens gets too big for higher magnification which causes the lens to sag

Modern materials used in lenses have improved the quality of images.  The refracting telescope can provide good images of the moon, planets and other deep space objects.
Modern refracting telescopes have “Go to” controllers which can point the telescope to any object the user specifies. Special azimuth motors will track the object overtime. This makes locating objects in the night sky easier for even amateurs.


Protecting your Telescope Lenses from Dust


Dust is present everywhere around us. It is only natural that sooner or later your telescope will be coated with a layer of dust. While a thin layer of dust will not probably interfere with your image. A thicker layer can affect your image. Hence, it is essential that the telescope lens is protected from dust.

Telescopes are provided with covers. Always fit the covers over the lenses when you are not using them.  Some astronomy shops provide compressed air to clean the lenses.

Never touch the surface of the lens with your bare hands. The oils in skin can affect the coating on the glass.  Never blow into the lens, droplets of saliva can get deposited on the surface and damage the lens.

How is collimation done in a telescope ?

Collimation refers to the process of adjusting the different components of the optical system such as lens, prism and the mirrors. A telescope which is not collimated will result in blurry images. 

Different types of telescopes have different methods of collimation.

How to collimate a telescope ?
http://www.viewfromascope.com/how-to-collimate-a-telescope/



Binoculars for Astronomy

Once you are familiar with the basics of the night sky, you can take the next step with binoculars.
Binoculars are great for astronomy as they give a wider field of vision though they have lower magnification. They are also cheaper than telescopes.  Binoculars are portable and are easily available.

Binoculars are specified on the basis of the magnification as well as the aperture size. A bigger aperture size permits more light to enter and provides clearer images.

For instance, 8 x 40 means that the binocular has a magnifying power of 8 and an aperture size of 40.

Common specifications are 7 x 35, 8 x 40, 10 x 50, etc.

A binocular will greatly increase you reach into the sky.  It is estimated that with binoculars an astronomer can watch nearly 100,000 stars.

Check out these resources on choosing a good binocular.

http://www.skyandtelescope.com/astronomy-equipment/binoculars-for-astronomy/