Celestron was the first large scale commercial manufacturer of the Schmidt-Cassegrain telescope, introducing its “C8″ 8” diameter 2032 mm focal length, ƒ10 telescope in 1970.[7] The primary innovation Celestron/Tom Johnson came up with was a way to produce Schmidt corrector plates using a vacuum to pull the glass blanks into a pre-shaped curve mold called a “master block” during the polishing process. This allowed for the inexpensive mass production of corrector plates of uniform shape. The telescope line had a trademark matte orange tube (changed to glossy black in 1980, and back to semi-gloss orange in 2006), and double-fork equatorial mount, and became a popular large aperture, compact design.
