THREE ASTRO-TECH EXTENSION RINGS FOR ASTROTECH RITCHEY-CHRÉTIEN ASTROGRAPHS - ONE 2" AND TWO 1" RINGS

Three metal threaded extension rings (one 2" and two 1") used to fine tune back focus on the AT12RCT depending on your imaging train. Can be used individually or in any combination to achieve the right back focus specs for the camera. The extenders are solid metal tubes, threaded on both ends designed to thread onto the 117mm port on the AT12RCT rear cell and the focuser of your choice. The 2" threaded ring weighs 14.4 ounces, the 1" rings weigh 7.2 ounces each.