Focal Reducer, 2", 0.7X

The Antares FR2-0.7X is the same 4-element f/6.3 lens system used for f/10 Schmidt-Cassegrain telescopes but in a 2" barrel threaded for standard filters. It is recommended for increasing true field in telescope with f/ratios of f/10 or higher. Focal length reduction is around 0.7X, but the exact reduction factor depends on the lens positioning between the objective and image plane.