ZWO FF80 APO Reducer

ZWO FF80 APO Reducer should be treated as part of the optical prescription, not a generic accessory. The right reducer or corrector can flatten the field, improve corner stars, and in reducer form make the system faster and wider.

Spacing, tilt, and sensor size are the entire game. Even a premium corrector will disappoint if the camera sits at the wrong distance or the focuser cannot hold the train square.