This chapter covers the two major accessories that are used with virtually all telescopes – finders and eyepieces – along with some possible upgrades, such as an improved focuser. A finder and, usually, a pair of eyepieces are supplied with all telescope/mount packages, but if an optical tube assembly is being bought by itself these may not be provided, so allowing you to choose those that will fit your needs best. When coupled with a 2-inch wide-field eyepiece, the short-focal-length refractors that are now in common use have sufficiently large fields of view that a finder may well not be needed. With the increasing use of computerised ‘go-to’ mounts a finder will be used only during the initial alignment on bright stars. This has made it possible for finders without ‘magnitude gain’ (i.e., not employing a small telescope) to be commonly used.

Over the years, telescope eyepieces have become increasingly sophisticated – but also more expensive. It is now very easy to spend more on a high-quality eyepiece than the initial cost of a telescope, particularly if it is bought second-hand, and this rather goes against the grain. It was only after I had spent a large sum buying my Takahashi fluorite refractor that I felt justified in spending a significant amount on eyepieces. They did not then seem quite so expensive! One general point with respect to eyepieces: the simple eyepieces that are often provided with beginner’s telescopes, perhaps with just three elements, are not necessarily of low quality. The fact that fewer glass elements are used can be a good thing, in that there are fewer internal interfaces between the optical elements themselves and the air surrounding them, so minimising scatter and light absorption and thus giving higher-contrast images. ‘Simple’ eyepieces are much prized by planetary observers for whom contrast is so important. Their only real loss as compared with premium eyepieces is the fact that the available field of view will be smaller.