NavList:

Bill Morris wrote:
) Let us agree that the "star telescope" is a Galilean of low power, having a positive objective lens and a negative eye lens (two lenses).

2) To Lecky, the "inverting telescope" was a Keplerian, having a positive objective lens and a compound positive eyepiece (three lenses).
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I am a bit confused. I thought that a simple two lens telescope inverted the image, and a three lens telescope produced an erect image.

In nautical literature of the 18th and 19th century, I have come across references to naval officers using a 'night glass'. The ordinary day time telescope was a terrestrial one, with an erect image. After sunset, they might use a night glass with one less lens, which gave an inverted image but more light transmission.

Don Seltzer
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