In the past there has been considerable discussion by those involved in amateur telescope making on the relative merits of reflector and refractor. From the standpoint of professional astronomers, there is no serious competition between them, as each type supplements the other in a well-rounded observing program.

Amateur telescope making is a fascinating hobby. In general, for visual work, low-ratio telescopes with their wide fields are useful for comet seeking, variable star work, and the like. The higher ratios are used in planetary study, double star observations, and in other fields where high powers and fine definition are required.

In 1733, the achromatic lens was invented by Chester Moore Hall, an English barrister. This was accomplished by combining a convex crown and a concave flint lens in such a way that their focal lengths were inversely proportional to their dispersions.