FUJIFILM FUJINON TELECONVERTER XF1.4X TC F2 WR
1.4× rear teleconverter for Fujifilm X
US 11,079,573 B2 — Tetsuya Ori
7 ELEMENTS / 4 GROUPS | 1.4× REAR CONVERTER | 2 ASPHERICAL SURFACES
A dedicated converter: it mounts only on lenses made to accept it. A teleconverter has no aperture stop of its own, so it is shown attached to a host lens, where the lens's stop stays the system stop and the focal length and f-number both grow by the converter's factor.