Focal Reducer, Schmidt-Cassegrain

The Antares SCTFR is the standard thread-on F/6.3 4-element fully multicoated reducer/corrector used on F/10 Schmidt-Cassegrain telescopes. It is actually only a reducer, but it does increase true field at the expense of some increase in spherical aberration and some vignetting (dimming) at the edge of the field.