First Telescope Advice

Department stores and toyshops sometimes sell simple telescopes, but these are not intended as serious astronomical instruments, and are best avoided. There are plenty of telescope dealers in the UK, who advertise in the magazines Astronomy Now and the BBC Sky at Night magazine,and most of their websites have pages with advice about choosing a first telescope. Your local astronomy club is another good place to get information: go along to a meeting or an observing evening, ask for advice, and try looking through different kinds of telescopes.

Refractors (lenses) and reflectors (mirrors) are the traditional types of telescope. Cheaper refractors can suffer from coloured edges around bright objects, and the eyepiece can be low down when looking at objects overhead. Reflectors generally have the most aperture for the cost, and can show fainter objects, but the eyepiece height can vary a lot so they can be harder to use while seated. Mirror-lens types can be a bit more expensive, but are light and compact, and the eyepiece height stays much the same wherever the telescope is pointed.

Other things being equal, a larger aperture (diameter) will show you fainter stars, fainter deep-sky objects and more detail on planets and the Moon. However, a large aperture telescope will be heavier, it will take longer to set up and put away, and longer to cool down. It will also be a lot more expensive. A good starting point is an aperture around 3 to 4 inches/7.5 to 10 cm for a refractor, or 5 to 6 inches/13 to 15 cm for a reflector. There are several brands of telescope with apertures in this range that are intended for newcomers to astronomy. They are generally good value for money, and available in all the different types described with a choice of mountings.

A good mounting is just as important as good optics: the best optics in the world won’t show you much if you can’t keep them steady. The mounting should be sturdy enough to support the weight of the telescope without sagging, have smooth movements and allow the telescope to be balanced properly. Basic (altazimuth) mounts rotate about horizontal and vertical axes, and the telescope must be moved in both directions to keep an object in view. Equatorial and fork mounts have one axis aimed at the Pole star, and need only be moved in one direction to follow the stars. Such mounts can be motorized so the telescope tracks an object in the sky. This is important when using higher magnifications, for example when observing planets.

GOTO mounts use computer control to point the telescope at an object you select from a database. This can be useful, but it means a smaller fraction of the price goes on the optics and mounting. They can be harder to set up than you expect, and you do need to know enough of the bright stars to confirm the setup is done correctly. You may ultimately find that learning your own way around the night sky is more satisfying than letting a computer do it for you.

A good pair of binoculars, such as 7 x 50 or (better) 10 x 50, will show you a lot in the night sky. They work well for viewing the Milky Way, star clusters, bright comets and the brighter galaxies and nebulae, and are also useful during daytime. It’s a good idea to look at some reviews online before you buy, and choose a pair of reasonable quality. If you use a tripod or some other kind of stand to support the weight of the binoculars while you look through them, you will be able to observe with them comfortably for longer periods.

Ideally it should take no more than five minutes (ten at most) from when you decide to observe until you are outside, warmly dressed, sitting comfortably and looking through the eyepiece. You can then take advantage of short periods when the sky is clear (very important in the UK!). If you have a small telescope that is easy to set up and use, you are likely to use it much more often than one that is heavy and takes a long time to get ready.

If you keep your telescope in the house it will need time to cool down before it gives a really sharp image, so if possible take the telescope outside half an hour before you want to start using it. This is especially important for reflectors and mirror-lens types, less so for refractors. The mirror of a reflector changes shape while it is cooling down, which can distort the image. As the telescope tube cools down, air currents can be set up inside it which will disturb the image. This is most likely when the optical tube is closed at the ends, as with refractors and mirror-lens designs. The best place to store a telescope is a shed or garage that is not heated, and doesn’t get too hot during the day. Keep this in mind when you are choosing what sort of telescope to buy and where to keep it.

You will see much more if you sit down to observe. When you are relaxed and sitting comfortably you can concentrate on what you are looking at, instead of trying to hold your head steady in an awkward position while crouching or standing on tiptoe. If you don’t already have a suitable garden chair, think about buying one at the same time as your telescope. A small step-ladder can be useful to get to the right height to look through the eyepiece of a reflector.

Use your telescope as often as you can: that is why it needs to be quick and easy to set up. Observing through a telescope is a skill that you have to learn, and then practice regularly in order to get better at it, just like swimming or playing a musical instrument. The first time you look at something through a telescope, you may be disappointed at how little you can see. Don’t let this put you off! Keep trying, and after a few nights you will find you can see more and more (but don’t expect views like pictures from the Hubble Space Telescope).

Dress warmly with multiple layers, especially in winter. Astronomy involves a lot of sitting or standing still in the cold, without the benefit of any activity to generate heat. Most heat is lost through the head and feet, so a warm hat or hood, boots and a second pair of socks are a good idea. If you feel cold it will be harder to concentrate on what you are looking at. Camping shops sell chemical hand-warmers and electrically-heated clothing for those really cold nights.

Learn to recognise some of the brighter constellations. You can use them as signposts to find your way around the sky and locate objects you want to look at. Astronomy magazines all have a guide to what’s visible each month, along with a sky chart. There are also plenty of good introductory books about astronomy, and huge amounts of information on the Web.

Finally, don’t forget to just enjoy looking at the night sky from time to time. Have fun!

Chris Hooker