The History Of Refracting Telescopes

The telescopes Galileo used included a convex(meaning curves outwards) and a concave lens (bends inward), while his contemporary Johannes Kepler, began using telescopes with two convex lenses. But, both telescopes were refracting telescopes.

Polishing methods at the time, only worked well on surfaces without much curvature. Therefore, the only way to make telescopes that could see long distances was to make keep extending the length of the telescopes with wider lenses.

There was one time when Christian Huygens in Holland was using a 23-foot long telescope with lenses that were several inches in diameter. In Germany Johannes Hevelius used an instrument that was 60 feet long.

Eventually the refracting telescopes became too long and unwieldy, that it was impossible to get good results. Just to lift them up and point in the right direction was incredibly difficult and cumbersome.

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