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Advice on buying a telescope ...
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Astronomy is a fascinating hobby and opens up a whole new
world of discovery. The most important tool of the astronomer
is the Telescope (although sometimes a good pair
binoculars may be used). We have chosen
our range of telescopes in such a way that they represent
a very good trade-off between quality and price. These telescopes
are powerful enough to enable amateur astronomists to discover
a wealth of hidden secrets in the night sky, without having
to pay the earth!
What will the telescope be used for?
Telescopes are often used for nighttime astronomical observation. However, a good telescope can also be used for daytime use. Some telescopes, such a refractors and Maksutov-Cassegrains are well suited to daytime terrestrial use as you look along the tube, rather than from the side as with reflector telescopes. In terms of nighttime viewing, some telescopes are designed more for planetary observations, and some are more suited to deep-sky viewing (nebulae, galaxies etc). In general, however, a good quality telescope will be sufficiently good for all nighttime viewing.
Who will be using it?
If you are buying a telescope for the first time, you will
need to balance cost and simplicity against the need to
buy a more powerful instrument at a later stage, should
your interest develop. If you are buying a telescope for
a child, you will need to condider the advantages of buying
a telescope that the child can cope with now, yet will also
be something they can grow into (far better to grow into
a telescope, rather than start growing out of it after the
first few weeks of use). You should also consider portability
and storage. A large telescope is not as easy to transport
or store, so you may prefer to choose a more compact design.
How much should I spend on a telescope?
Broadly speaking, there are three quality bands for telescopes.
High end telescopes, such as our Skymax
180 Pro EQ6, Evostar
150 Pro occupy the top band. These combine highly-tuned
optics with very heavy-duty mounts. These telescopes are
often purchased by specialists who require the very best
quality images, kept dead-still over time within view, usually
in order to enable long-exposure photographs to be taken.
Such telescopes are also purchased by amateur astronomers
simply looking to buy a top-of-the-range telescope. Upper
Mid-range telescopes, such as the Skyliner
300P, STARTRAVEL-102 SynScan™, SKYMAX-102 SynScan™
combine top performance in a few chosen areas, such as aperture
size, quality of mounting, or lens perfection, with lower
prices. Good Mid-range telescopes are by far the
most popular among serious amateur astronomers and families
looking for a good telescope that will reveal many of the
secrets of the night sky (under £100 up to about £350).
Within the mid-range band, you will find different types
of telescope, and when considering which one to buy, your
decicison may be based on a number of factors, such as who
is going to use it, where it is going to be used etc (we
will cover these aspects below). The third band is what
we term Entry-Level telescopes. The number of budget
telescopes available on the market is increasing, often with cheaply-made
models whose quality leaves a lot to be desired. We therefore
advise our customers to be wary of buying this sort of telescope, and to stick to well-known brands if possible.
Good examples of Entry-level telescopess are the Mercury 707 and Astrolux models.
What defines a good telescope?
The most important thing to look
for in a telescope is the quality of the lenses and mirrors.
Generally speaking, the larger the diameter of the LIGHT
COLLECTOR (on a refractor telescope, this is the diameter
of the objective lens, on a reflector telescope, this is
the diameter of the main mirror), the more light can be
collected, and hence the greater the quality of the magnified
image. Usually, the more you pay, the higher the quality
of the magnified image. This is not always the case though
among the telescopes we regularly review. After the quality of the optic, the next most important thing to look at is the telescope mount. The telescope mount should be sturdy enough to keep the telescope rigidly fixed on its target since, at higher magnifications, any movement of the telescope tube will cause the object you are looking at to move erractically in and out of view, making observation impossible.
Can a beginner use a high-end Telescope?
Or, to put the question another way, can a beginner cope
with a large, powerful telescope? The answer
is yes, especially if you select a model that has an auto-pointing function. These telescopes allow you
to just turn on and start oberving. The advantage of
buying a good telescope up front is that it means
you will not have to upgrade at a later date.
Should I consider cheap telescopes?
You will see a number of cheaper telescopes on the market
and they are often sold under unfamiliar names. The most
important thing to be aware of is that a telescope's ability
to find interesting objects depends on the quality of the
optics. Established telescope brands do not only use more
sophisticated optics, but the optics are highly tuned
to optimise performance. In addition, lower quality telescopes often try to seduce the buyer with high magnifications that are beyond the real capabilities of the instrument. The maximum practical magnification of a telescope is roughly the aperture diameter in mm, divided times 2. Therefore
Types of Telescope
There are two main categories
of telescope: RefRACtors and RefLECtors. Refractors,
use two or more lenses to collect and focus the light from
an object to the eye of the observer (or a digital camera
sensor), and can trace their design back to the telescopes
of Galileo’s era. Reflectors, developed by Isaac
Newton in the 17th century, use mirrors to focus the light.
As magnifications increase, impurities in the glass of lenses
can cause distortion (commonly a “rainbow-like” halo around
objects) requiring expensive and difficult treatments and
coatings to correct. Reflectors telescopes avoid this problem,
and are generally cheaper to manufacture for a given sized
aperture (the main lens or mirror used to catch the incoming
light). As a result, most high-performance optical telescopes,
including the Hubble Space Telescope, are reflector designs. Dobsonian telescopes are Reflector telescopes mounted on a Dobsonian mount, rather than on a tripod. The advantage of these telescopes is that the Dobsonian mount is a very cost-effective way of providing a rigid support for your telescope, so for a given budget, you can invest more in the telescope itself. The disadvantage of a Dobsonian telescope is that it is not practical to use when the telescope is in a horizontal position, so they are used exclusively for nighttime use, rather than daytime terrestrial viewing.
Maksutov-Cassegrain telescopes belong to the "Catadioptric" family of telescopes are a bit like a hybrid between refractors and reflectors, comprising both mirrors and lenses. These are excellent instruments that are shorter in length than reflectors, but still offer great results, and you look along the tube, rather than sideways into the top of the tube, making them a bit more intuitive to use than reflectors.
What About Accessories?
The most important area to spend your money is on the
telescope itself. Once you have chosen your telescope, you
may wish to consider accessories. Extra eyepieces are often useful, so you can raise the magnification of your telescope. The most important property of an eyepiece is its focal length. The shorter the focal length, the higher will be the magnification of your telescope. The magnification is calculated by the dividing the focal length of the telescope by the focallegth of the eyepiece. Filters are also useful to help pick out more detail, for example when observing planetary surface features. There are many eyepieces and filters available, and these are often purchased once you have already gained experience of your new telescope. Another popular accessory of a camera mount, enabling you you use your digital camera to record your observations.
Spare Parts & Guarantees
Always make sure that you are able to buy spare parts and
standard accessories for your telescope. You need to make
sure, therefore, that your telescope manufacturer will
still be around after that time. The manufacturers from
whom we select our telescopes are all very well established
companies, and we supply their full range of spare parts.
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”I have used a great number of telescopes; some are good, some mediocre and some bad. To me the Sky-Watcher range of instruments are very good indeed, and suited to amateurs of all kinds – and they are not priced out of the market! Excellent value.
Use them and enjoy them.“
Sir Patrick Moore CBE FR
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