Telescopes

Radio telescopes as well as communication antennas operate under the influence of gravity, temperature and wind.

The modern aspiring astronomer is faced with a bewil­ dering choice of commercially produced telescopes, including all the designs considered in the preceding chapter. Yet only four decades ago the choice for a small telescope would have been between just a refrac­ tor and a Newtonian reflector. That change has come about because of the enormous interest that has grown in astronomy since the start of the space age and with the mind-boggling discoveries of the past 30 or 40 years. Except for some of the very small instruments which are unfortunately often heavily promoted in general mail order catalogues, camera shops and the like, the optical quality of these commercially pro­ duced telescopes is almost uniformly excellent. Although one product may be slightly better for some types of observation, or more suited to the personal cir­ cumstances of the observer, than another, most of them will provide excellent observing opportunities. The same general praise cannot be applied, however, to the mountings with which many of these telescopes are provided, and those problems are covered in Chapter 6.