The Planetary Dobs

Abstract

A revolution, by necessity, must permeate all rungs of society and evince changes to that society that are palpable and long lasting. The Dobsonian “movement” didn’t become a “revolution” until it could reach out from its traditional hinterland of deep sky nirvana and begin to make inroads into niches traditionally dominated by other kinds of ‘scopes. We’re thinking, of course, of planetary observing, where the smaller aperture, high-quality refractor has traditionally dominated. To compete with the refractor (or Maksutov Newtonian for that matter) a reflector ought to have a high focal ratio to allow comfortable high power views to be achieved. It ought to have exceptional contrast by minimizing stray light as well as possessing a central obstruction less than 20 percent. Such a telescope, optical theory suggests, ought to behave as a superb lunar, planetary, and double star ‘scope, rivaling a refractor costing many times more.