The Ultimate Guide to Celestron Optical Tubes | Celestron
Why are the views through telescopes inverted? - Quora
Amazon.com : Celestron 45-Degree Erect Image Diagonal, A Great Accessory for Daytime Terrestrial Viewing!, Multi (94112-A) : Refracting Telescopes : Electronics
Why are Newtonian telescopes so often pointing backwards/upside-down in television shows and movies? I've always found this distracting and would love to know the reason behind it. - Quora