Telescopes act as windows to the universe. It is with the help of telescopes
that we can study the solar system and view the conjunctions of stars. Not just
that, the various planets, galaxies, satellites and asteroids that we get to see
only in the books and magazines are made more familiar to us via the telescopes.
They act as barrier- breaking instruments between the human beings and the outer
space. The universe is no more a mystery to us that exists beyond our reach and
we owe it all to the telescopes.
The modern day telescopes bring with them a wide array of accessories and it is
with the aid of these accessories that it becomes much more easier to
successfully put the telescopes into proper use. Let us see what are the
important accessories that go well and are a “must-have” for most telescope
users: -
Filters- These are very essential for telescope users because they reduce the
glare on the eyepiece and scatter the light thereby making it less strenuous for
us to view distant objects.
Eyepiece- this is a very important piece of equipment and its absence can render
a telescope useless. Eyepieces come in a variety of sizes and if you add more
than one eyepiece to your telescopes then you can have the pleasure of viewing
even the tiniest and distant objects with clarity.
Mounts- Mounts are the stands for telescopes. It is a mount on which the
telescope rests. Since a telescope wont function favorably in vibrations
therefore you should ensure that it is placed on a stable mount.
Barlow lens- A Barlow lens helps in the magnification of telescopes. These
lenses are available in different sizes and we must be careful in choosing the
size that best fits the eyepiece.
There are two main types of telescopes, the refractor (Galileo) telescopes and
the reflector (Newton) telescopes. The refractor telescope uses an objective
lens that bends the light towards the eyepiece. While the reflector telescope
uses a mirror, which collects the light and then directs it towards the
eyepiece.
Though both the refractors as well as the reflector telescopes are easily
available in the market we should take the following points into consideration
before buying a telescope.
Do not get impressed by the magnification of the telescopes. This is because
magnification alone is of no use if it just produces large but hazy images.
Aperture- This is the most important factor while deciding on a telescope.
Aperture is the opening that collects light so its important to choose a
telescope with a larger aperture that will ensure a clearer and a more detailed
image quality.
Resolution- This enables the telescopes to produce a more detailed image. So
always opt for a telescope, which has a higher resolution. Moreover since
resolution is also determined by the aperture, therefore the larger the aperture
the better the resolution.
Focal length- The distance between the optical center of the lens or the mirror
and the optical center of the eyepiece is known as the focal length. The focal
length is what determines the magnification in telescopes. Larger focal lengths
imply more magnification.
If we are careful about remembering the above points then it wont take us long
to choose a telescope the next time we want to buy one for ourselves.
Telescopes – Principle Of Operation And
Factors That Affect Its Properties
by: David Chandler
Telescopes are devices that are used to view the distant objects. They find its
use in astronomy and physics. It enables you to view the distant objects by
magnifying them. There are many types of telescopes and their prices vary
according to the specifications. Many accessories are also available that can be
used in conjunction with the telescopes. Small telescopes that are used as toys
are also capable of viewing some objects around 50 meters away.
Principle in which the telescope works
The principle in which the telescope works is very simple. There are two lenses
that make up the task of viewing the objects that are at a distance. One of the
lenses picks up the light from the object viewed and makes it available at a
focus point. Another lens picks up the bright light from the focus point and
spreads it out to your retina so that you can view. The lens that picks up the
light from the object is called the objective lens or primary mirror. The lens
that picks up the light from the focal point is called the eyepiece lens.
Factors that affect the viewing of the object
The capability of the telescope to collect the light from the object that is
viewed and the capability to enlarge the image are the factors that affect the
efficiency of the telescope. The capability to collect light from the object
depends on the diameter of the lens or mirror, which is otherwise called the
aperture. The larger the aperture the more the light it can collect. Enlarging
of an image depends on the combination of the lenses that are used. The eyepiece
in the telescope performs the magnification.
Some of the world's largest optical telescopes in operation
We say a telescope to be larger based on the aperture size. Based on this we can
say that Keck and Keck II are the largest telescopes in operation with an
aperture of 10 meters diameter. The Keck telescope is composed of 36 mirror
segments. This is located at Mauna Kea, Hawaii. The next largest is Hobby-Eberly
located at Mt. Fowlkes, Texas which has an aperture of 9.2 meters. You can get a
list of the largest optical telescopes at
http://astro.nineplanets.org/bigeyes.html.
Choosing your telescope
The choice of the telescope largely depends on what you want to observe. You can
choose compound telescopes and refractor type of telescope for viewing through
the urban skies. For the rural skies, you can use compound telescopes and
reflectors. They are better than the refractors type of telescopes. Each type
has its own advantages and disadvantages. Hence, many people have different
telescope for different purposes.
Types of Telescopes & What Are The
Advantages Of Each
by: Jeremy Hier
Refractors, Newtonian reflectors and Catadioptrics are the three main types of
telescopes. All these different types have the same purpose, but each telescope
design does it differently. Collecting light and bringing it to a point of focus
so it can be magnified and examined with an eyepiece is their goal.
Of the different types of telescopes the refractor is the telescope most people
think of when they think of astronomy. This type of astronomy telescope is easy
to use and reliable due to the simplicity of design. It requires little or no
maintenance. Its great for looking at the different types of lunar, planetary,
and binary stars.
Newtonians are a type of telescope, which is also known as catoptrics. This type
is different from the other telescopes because it has the lowest per inch of
aperture compared to refractors and Catadioptrics, because lenses are more
expensive to produce than mirrors, especially in medium to large apertures.
Newtonians deliver very bright images and are low in optical aberrations.
Catadoptric telescopes are the most popular type of instrument, with the most
modern design, marketed throughout the world in 3 1/2 and larger apertures. Its
very good for looking at different planetary, lunar, and binary stars. If you
like to take photos with your telescope this type of instrument is excellent for
deep sky observing or astrophotography with fast films or CCD's.
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