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Refractors:the Perfect View?

There are really only three types of telescopes, refractors, reflectors and catadioptrics. If you have ever shopped online for a telescope, you may have seen what seemed like hundreds of different types, but most of what you saw represented simply the seemingly endless variations of the reflector. Basically a refractor uses two lenses to gather light and bring it to focus. A reflector uses a mirror, and a catadioptric scope employs a system of both mirrors and lenses.

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A refractor is what most people envision when they think of telescopes-- a long, thin tube on a spindly tripod with an eyepiece projecting from the back end of the tube. In researching telescopes, particularly on internet forums, the newcomer will soon discover that refractors have a following of aficionados who would never dream of using anything else, or even admitting that equally good optical systems exist. Some of this loyalty is rooted in fact. Some of it is simply due to the refractor's romantic appeal, which is understandable. The refractor was, after all, the first astronomical telescope ever used.

Galileo Galilei’s first telescope, built in 1608 by Hans Lippershey, a

was 38.5 inches in length. It collected light through a sperical primary lens, then brought it

to a focal point via a concave eyepiece lens. He later called his version of

Galileo Galilei used a refractor, his “telescopio” (Greek for “to see at a distance”) when he became the first to observe Jupiter's four largest moons. Galileo didn't invent the telescope, though it has been said that he did little to dispel that notion. Spyglasses had been used for military purposes in Holland. Galileo purchased a few examples from a Dutch lens maker named Hans Lippershey. He made improvements, adapting them for astronomical use in 1609. These scopes had a convex primary lens that curved outward and a concave eyepiece curving inward. They were small, two-inch instruments with a limited field of view and poor resolution by our standards, but they enabled him to see more of our solar system than any human being before him.

Ultimately Galileo's refractors got him into trouble. Through his telescopes, it became obvious that Copernicus had been right, and that the Earth was not the center of the universe. Understandably, being a rational person, he couldn't foresee the reaction of the Church, whose leaders were still not ready or able to reconcile their beliefs with this new scientific evidence that was becoming evident to more and more people. Galileo, one of the most important people in human history, lived out the remainder of his life under house arrest.

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