A small magnet assembly is scanned in a retrograde planetary or epicyclic path about the back of a target being plasma sputtered including an orbital rotation about the center axis of the target and a planetary rotation about another axis rotating about the target center axis. The magnet assembly passes through the target center, thus allowing full target coverage. A properly chosen ratio of the two rotations about respective axes produces a much slower magnet velocity near the target periphery than at the target center. A geared planetary mechanism includes a rotating drive plate, a fixed center gear, and an idler and a follower gear rotatably supported in the drive plane supporting a cantilevered magnet assembly on the side of the drive plate facing the target. A belted planetary mechanism includes a fixed center capstan, a follower pulley supporting the magnet assembly, and a belt wrapped around them.