SONY 2x TELECONVERTER SEL20TC
2× rear teleconverter for Sony E
WO 2017/134928 A1 — Yonghua Chen, Naoki Miyagawa
8 ELEMENTS / 5 GROUPS | 2× REAR CONVERTER | 1 ASPHERICAL SURFACE / 1 ELEMENT
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.
Mount it on a lens (4 lenses)
SONY FE 400-800mm f/6.3-8 G OSS— 27 ELEMENTS / 17 AIR-SEPARATED GROUPS, 7 FUNCTIONAL ZOOM GROUPS, PATENT f = 399.99–775.96 mmSONY FE 400mm f/2.8 GM OSS— 22 ELEMENTS / 16 GROUPS, DESIGN f ≈ 388.15 mm, DESIGN F/2.91SONY FE 70-200mm f/2.8 GM OSS— 23 ELEMENTS / 18 GROUPS, f = 72.1–194.0 mm, F/2.88SONY FE 70-200mm f/2.8 GM OSS II— 17 ELEMENTS / 14 GROUPS, f = 72.1–194.0 mm, F/2.88