References:
Telescope - Wikipedia
https://en.wikipedia.org/wiki/Telescope
Refracting (Refractor) Telescope - Wikipedia
https://en.wikipedia.org/wiki/Refracting_telescope
Reflecting (Reflector) Telescope - Wikipedia
https://en.wikipedia.org/wiki/Reflecting_telescope
Catadioptric Telescope - Wikipedia
https://en.wikipedia.org/wiki/Catadioptric_system
Schmidt-Cassegrain Telescope (extra telescopes that give examples of catadioptric telescopes) - Wikipedia
https://en.wikipedia.org/wiki/Schmidt%E2%80%93Cassegrain_telescope
Dobsonian Telescope (type of Newtonian telescope) - Wikipedia
https://en.wikipedia.org/wiki/Dobsonian_telescope
Telescope Focal Length - starlust
https://starlust.org/telescope-focal-length/
Achromatic Lens - Wikipedia
https://en.wikipedia.org/wiki/Achromatic_lens
Apochromatic Lens - Wikipedia
https://en.wikipedia.org/wiki/Apochromat
Gregorian Telescope - Wikipedia
https://en.wikipedia.org/wiki/Gregorian_telescope
Newtonian Telescope - Wikipedia
https://en.wikipedia.org/wiki/Newtonian_telescope
Petzval Field Curvature - Wikipedia
https://en.wikipedia.org/wiki/Petzval_field_curvature
Comatic Aberration - Wikipedia
https://en.wikipedia.org/wiki/Coma_(optics)
Distortion - Wikipedia
https://en.wikipedia.org/wiki/Distortion_(optics)
Schmidt Corrector Plate - Wikipedia
https://en.wikipedia.org/wiki/Schmidt_corrector_plate
Ritchey-Chrétien Telescope - Wikipedia
https://en.wikipedia.org/wiki/Ritchey%E2%80%93Chr%C3%A9tien_telescope
Telecompressor (Focal Reducer) - Wikipedia
https://en.wikipedia.org/wiki/Telecompressor
Barlow Lens - Wikipedia
https://en.wikipedia.org/wiki/Barlow_lens