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Stargazing on a budget

Updated Wednesday, 4th August 2004

You don't need to invest in your own radio telescope to explore the night sky - you can get great results with really simple kit

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Watching the skies

Binoculars for beginners
A sensible start for beginners might be to invest in a good pair of binoculars. These are much better value for money than the small telescopes found in catalogues and toy shops.

You'll find binocular sizes are given as: magnification x diameter of objective lens. The smallest sets of binoculars, such as 7x20 or 8x21, or compact binoculars, are more suited to bird-watching than astronomy because they do not give a bright enough image at night.

The minimum specification for astronomy use is around 7x50, which should cost around £50 - £100. Better images can be seen with 10x50s, but the price will increase accordingly. A pair of 11x80s would give resolution good enough to see Saturn’s rings and the craters on the moon - these would set you back around £400. It is advisable to mount larger binoculars on a tripod with a clamp to keep them steady. There are many good makes of binoculars and tripods, about which any telescope or camera shop should be able to advise. Of course, you can save a lot of money by buying things second-hand from magazine adverts or the internet.

Ann Bonell, President of Leicester Astronomical Society, has this advice for first-time buyers: "Before purchase, test the binoculars by focusing on a distant object such as a TV aerial. If the binoculars are OK, you should see a perfect image with no double imaging or colour fringing. If there is any misalignment, then reject them."

A first telescope
There are two types of telescope - reflectors, which use a mirror at the bottom of the telescope to image, and refractors, which have a lens at the top of the tube. It is the diameter of the mirror or lens that determines the resolution - the bigger the diameter, the better images you will see. Small telescopes are generally not worth the cost - refractors below 3” diameter and reflectors below 4” are generally not as good as the binoculars described above. Also important is a sturdy tripod to mount the telescope on, as the ones provided can sometimes be too unsteady for a clear image. A stand with a pillar and feet is best for the purpose.

Andrew Conway from the Open University makes the following recommendations:
"4" to 5" reflector telescopes: many imported Russian ones are available for under £300. Pros: They are cheap, sturdy and have good optics (i.e. give very sharp images). Cons: They are heavy and not very portable, difficult to upgrade, and rather basic.
Celestron and Meade have a variety of 5" and below reflectors which are very popular and have good optics and sturdy tripod stands. Pros: Good optics, light compact and portable. Easily upgradeable and have all kinds of add on gadgets. Cons: A bit more expensive and can sometimes be a little more fiddly to use because of their compact size."

Reviews of telescopes that have been available for the past few years, as well as the very latest models and prices, can be found on the Test Reports section of the Sky and Telescope magazine website.

Other useful astronomical equipment
The first and most useful thing for an amateur astronomer to have is probably a Planisphere. This is a star map on a disk that can be adjusted to show you a map of the night sky for a given time and date. There a re several different types available from different manufacturers and can be ordered from any bookshop. There are also many books available, such as Star Atlases, almanacs and guides to the night sky for the coming year. And don't forget our Virtual Planisphere.

There are many software packages now on the market which combine star maps, ‘computer planetarium’, on-line encyclopaedia and astronomical and space mission photo archives. It is worth checking out reviews before spending your money as there are many available free from various on-line sources.

Remember that the best astronomical resource of all is free – it is the night sky itself. Any effort expended in finding a dark site away from light pollution will be well rewarded.

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