Galilean, Keplerian, Newtonian and Conde

Oh ... what a giveaway (as someone once said).

If you google "Galilean, Keplerian, Newtonian and Conde", the top hit is to a page on quizballs.com, from which this and eleven of the next fourteen questions have been lifted.

Not that there's anything wrong with that per se. But if you're lifting questions wholesale from a site with dubious provenance, you really should do a bit of checking before you send them for use in the Quiz League.

There's just one minor issue with this particular question: Conde is not a type of telescope, but coudé is. (It's a minor issue because there were enough clues in the rest of the question to guide you to the correct answer.)

The first record of a telescope comes in a patent filed in 1608 by a Dutch spectacle–maker named Hans Lippershey, for an instrument "for seeing things far away as if they were nearby". A few weeks later another Dutch instrument–maker, Jacob Metius, also applied for a patent; this one was not granted (as "the knowledge of the device already seemed to be ubiquitous", according to Wikipedia).

The original Dutch telescopes were composed of a convex and a concave lens; telescopes that are constructed in this way do not invert the image. Lippershey's original design had only 3x magnification. Telescopes seem to have been made in the Netherlands in considerable numbers soon after this date of "invention", and rapidly found their way all over Europe.

The Italian polymath Galileo Galilei heard of the "Dutch perspective glass" in June 1609. Galileo states that he quickly solved the problem of the construction of a telescope by fitting a convex lens in one extremity of a leaden tube and a concave lens in the other one.

The German mathematician and astronomer Johannes Kepler wrote in 1611 that a convex ocular placed after the focal point of the objective would produce an image, but this approach had not caught on, as the lenses of the time were very poor and people found it easier to aim a scope that produced a direct image. Doubly convex telescopes are known today as Keplerian, as opposed to the concave ocular of the Galilean.

The Newtonian telescope uses a mirror, and is known as a reflecting telescope as opposed to a refracting one. Isaac Newton built his first reflecting telescope in 1668. The reflecting telescope has some advantages over the refractor, but also some disadvantages.

The coudé is a type of reflecting telescope that has plane mirrors positioned to reflect light from the primary mirror along the axis onto a detector. The French word coudé means 'bent' or 'angled'; 'coude' (with no accent on the 'e') is the French word for the elbow.

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