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Telescope Basics: Understanding the most common eyepiece sizes and types for telescopes

Hosted by David Fuller of “Eyes on the Sky,” this video goes over the various sizes and types of basic eyepieces for many amateur telescopes. The three most common eyepiece barrel diameters are discussed, as well as the types of lens configurations which determine how well the eyepiece forms an image for the user – including the concept of eye relief which can matter a lot to those who wear eyeglasses. Discussed are Huygens, Ramsden, Kellner, RKE, Modified Achromat, Plossl and some advanced designs, plus some information about anti-reflection coatings. An excellent primer for anyone wanting to understand more about telescope eyepieces.