Beginner's guide

Equipment

If you want to start equipping yourself, it is a good idea to start with a pair of binoculars, say of the 7x50 variety. A pair of binoculars consists of two small telescopes joined together in parallel. 7x50 means a magnification of 7, with the object glass of each telescope 50 mm in diameter. Binoculars are very useful for viewing objects such as stellar clusters and nebulae and they will give splendid views of the mountains and craters of the Moon. Remember NEVER to look at the Sun. If you do so severe damage to your eyes is inevitable.

Telescopes are of two main types. A refractor collects light by means of an object-glass, where as a reflector uses a curved mirror coated with a thin layer of aluminium or silver. Each type has its own advantages and its own drawbacks. The refractor is easier to maintain, and small refractors are portable . A good first telescope is a 3inch refractor - that is to say a telescope with an object glass 3 inches across. The light collected by the object glass is brought to focus, and the resulting image is magnified by an eyepiece. It is wise to however to select three eyepieces; one high, one medium and one low power. Usually the maximum useful power is 50 per inch of aperture; thus your 3'' telescope will bear a power of 3x50 = 150. If you want a higher power, you must use a larger telescope.

Very small refractors are limited in scope, but have improved in recent years, and a reasonable telescope can now be bought for little over £100. Never buy a telescope which is advertised by magnification alone. (It is the aperture which matters.)

Inch for inch, a reflector is less effective than a refractor, but it is also cheaper . A 6 inch is the smallest really useful reflector, but a 4 inch is not to be despised.

There are many optical systems, of which the most common for beginners is the Newtonian. Remember- always make sure that your telescope is firmly mounted. If not it will be certainly useless.

Astronomical photography can be fascinating. An ordinary camera can be used to take star trails, provided that kit can be used for time exposures. Photographing through a telescope can be done, but the telescope must be mechanically driven so as to follow the drift of the target object across the sky, due to the Earth's rotation.

Digital cameras are now taking over - we have come to the era of electronic equipment, now used by many serious amateurs. But when starting out, do not be too ambitious.

Excellent equipment can now be obtained for less than that of a rail ticket between, say, London and Glasgow.

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