Buying a telescope

Advice from the Society for Popular Astronomy

Buying a telescope can be tricky because there are so many poor quality instruments on the market. But there are also some good ones, so take care when buying yours.

• First, have you considered binoculars? They are better value than telescopes, are cheaper, and have other uses. And they're ideal for many forms of stargazing. Don't get cheap high-power or zoom types. 7 x 50s or 10 x 50s are ideal.
• Beware of non-achromatic telescopes! These are really toys, without colour-corrected lenses, but they may look good and make great claims. Check that there is not a plate with a hole in, behind the lens, to cut down the diameter.
• The view through your telescope should be sharp and clear, with little trace of false colour round the edges of objects. But don't view through a window - go outside. If you are not happy with the quality, get your money back.
• Don't rely on a daytime view - or on the sales pitch - for a guide to quality. The only way to be sure is to view at night and know what you are looking for.
• Beware of zoom telescopes! The extra lenses that vary the magnification also introduce distortions. And don't be impressed by high powers - a maximum of twice the aperture in mm is all you can use.

Maintained by Michael Oates Email: mike@ph.u-net.com Last modified 27th Aug 1996