 It also included a star chart engraved in white on a blue aluminum sleeve (this doubles as a dewcap), around the barrel which contained a moon map.To avoid a conflict with a design patent held by John Gregory licensed to PerkinElmer, Braymer put the secondary spot on the outer (R1) surface of the corrector lens.In the mid-1960s the patent issue was settled, and Questar’s Maksutov-Cassegrains after that time use the Gregory design with the aluminized spot on the inside of the corrector (R2).