1X Field Flattener for the Askar 80ED Refractor OTA This 1X Flattener is specifically designed for the Askar 80ED refractor. Its triplet design (with one element of ED glass) is optimized for APS-C. With this flattener installed you will achieve a flatter field and sharper, rounder stars at the edges, as it corrects for both field curvature and coma. The Askar 80ED 1X Flattener does not change the native focal ratio of the 80ED OTA; it remains at f/7. The back focus is 55mm (standard) as measured from the M48 threaded back surface. It weighs 0.42kg. There is no need for an addition filter drawer thanks to the built-in M48 x 0.75 2" filter thread. In addition, the flattener integrates with the 360º camera rotator of your 80ED. The entire unit is CNC machined and comes with a threaded metal cap on both ends. SPECIFICATIONS 80ED Focal length with Flattener Installed 560mm 80ED Focal ratio with Flattener Installed f/7 Number of Elements Triplet design (including one ED glass) Image circle APS-C Back Focus 55mm from the base of M48 male thread Weight 0.42kg Rear-end thread type M54×0.75 with M48×0.75 filter thread inside
