Astronomy for all!
Says Dr. Simon Bennett (our astronomer in residence): "The aim of The Widescreen Centre is to enhance the great pleasure that comes from the observation of heavenly bodies. There's a bewildering array of products available, but we aim to help you to arrive at the best possible option - for you! "
"If you've never bought a telescope before, you might even find the vast selection a trifle confusing. This is because that choice is now so great, with many different types from which to make that choice. However, on the following pages, I will stick to basics and try to avoid any confusion whilst explaining types that will benefit you personally".
RESISTING TEMPTATION
"Firstly, a word of warning. Resist the temptation to go for any telescopes that advertise themselves on their power, or with a zoom. When choosing an astronomical telescope it is not power that is important but aperture (the diameter of the main lens or mirror of the telescope). The larger this is, the more light it can gather and the more you will see. Remember, you'll be looking at objects in the night sky....and it's dark up there! "
Continues Simon: "While we are on the subject of power, there is a simple way of knowing how large a magnification a telescope could do under the best conditions. For every inch of the aperture (size of main lens) the telescope can magnify 50 time or if you are using mm's then 2x the diameter of the aperature. Simple eh?"
"So, for example, a 4-inch telescope could magnify 200 times (4 x 50=200), but you'd rarely use it. Or double the aperture in mm, 60mm = 120x. "On the following pages I'll take you through some of the very basics of observing so that you will gain some knowledge and understanding of where to start looking for the most suitable telescope for your own use - this will include types and price ranges . Just click on NEXT arrow and join me in the adventure and fun of practical astronomy."
The Telescopes. Refractor or Reflector?
Continues Simon: "Now to the actual telescopes. The popular conception of a telescope is a tube with one large lens at the front end and another smaller one to look in at the back. And, in fact, this type of telescope is known as a Refractor because the light is 'bent' or refracted through the glass lens. There is another type where the main lens is actually a mirror, this collects the light at the bottom of the main telescope tube and reflects it back up to a second - but small - mirror and into an eyepiece that is situated at the side: this type of telescopes is, naturally, called a Reflectors".
"Without getting too technical, the perceived wisdom is that a refractor is at a slight advantage in clarity when viewing planets in our Solar system. However, once you want a larger diameter telescope - and the larger the diameter the more 'light grab' it will have - a reflector is by far the cheaper option. This is because a large mirror is easier to make than a large glass lens. With the latter, anything over about 150mm in diameter becomes very pricey and is usually beyond the means of the average astronomer. At this stage, it is worth reminding ourselves that, in astronomical terms, by far the most important thing is 'light grab': and remember you are dealing with light that has travelled immeasurable distances and is truly 'faint' (even when it looks reasonably bright). The larger the telescopes aperture, the more light it will 'see', and this in turn will let you increase magnification if needs be".
"A plus point with a refracting telescope is that it requires little or no maintenance: lenses are set in the factory and rarely, if ever, ever need resetting. Reflectors can be knocked out of alignment - although this does not happen very often - but, in any case, it only takes a few moments and a bit of practice, to reset them. Both types of instruments are generally reliable and will give you years of excellent service if you treat them with care".
"If you want to get to know the various parts of a telescope then take a look at the Parts Pages".
"Want to buy, but have a question? Then why not to contact Simon on our phone 020 7935 2580 or his email: simon@widescreen-centre.co.uk
Here's some Supporting Features you should know about.
Simon Says: "An astronomical telescope is usually supported on a tripod or stand. However these are no ordinary tripods, because they have a special function. Anyone familiar with a standard photographic tripod will know that, when a camera is mounted on it, it can usually be moved along the horizon IN A STRAIGHT LINE! But celestial objects in the sky DO NOT go in straight lines, but rather in A CURVE. This has to be taken into account when fitting a tripod and mount to an astronomical telescope".
There are two commonly used methods:-
"1. The simple Alt-azimuth mount which allows movement left and right using slow motion controls across the sky (azimuth), and the raising and lowering of the barrel (altitude). With this mount the telescope has to be moved in two directions, simultaneously, to follow the stars as they move across the sky, in an arc, during the night".
"2. The second mount is the Equatorial. This, like the previously mentioned type, lets you move the telescope to any area of the sky but one axis of the mount can be lined up with the Earth's north/south axis. In doing this, as the earth spins on this axis, an opposite spin on the telescope will keep a planet or constellation in continuous view. This means that the telescope only has to be turned in one direction to track a star".
"This is much easier, and it's even better when a motor is attached to the mount, then the instrument tracks the heavens automatically, and all you have to do is to find your target....and the telescope stays there".
"There is also the more recent generation of telescopes that use electric motors on an alt-azimuth mount. Attached to these is a small computerised handset and the telescope then not only tracks an object, with the simpler mount, but it can also be made to point the telescope to the object in the first place!"
So the best telescope to buy is one that has the largest size of lens for the budget you can afford.
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