11. The basic SOON telescope is a evacuated refractor mounted on a polar axis. 12. A soft tissue refractor is used to allow for greater visibility and access. 13. There's also a desperate need for a Coffee Table Book Lighting Refractor . 14. Amateur astronomers use such instruments as the Refractor and the increasingly popular Maksutov telescope. 15. An auto-refractor is a computerized instrument that shines light into an eye. 16. The binocular auto-refractor measures sphere, cylinder, axis and pupillary distance. 17. It is housed in a building about 100 feet northwest of the Clark refractor . 18. It was donated to the refractor in 1966. 19. It was discovered by Lewis Swift in 1886 with a 16-inch refractor . 20. Orion offers a similar refractor model for less than $ 100 on its Web site.
