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