SONY E 20mm f/2.8

US 2014/0204265 A1 — Toshihiro Sunaga

6 ELEMENTS / 6 GROUPS
4 POWER GROUPS (+/−/+/−)
f = 20.421 mm (DESIGN)
F/2.89 (DESIGN)
2ω = 71.96°
5 ASPHERICAL SURFACES / 3 LENSES

Focus Mechanism

Rear focus: G4 (L6) moves 1.21 mm imageward from infinity to the patent short-distance state.

Optical Elements (6 physical; 7 modeled media)

ElementTypeGlass
L1Negative MeniscusS-TIL26 (OHARA; 567/428 catalog match)
L1rNegative Resin Meniscus (1× Asph)Unmatched (proprietary aspherical resin; patent nd=1.534, νd=41.71)
L2Positive MeniscusS-LAH65VS (OHARA; 804/465 catalog match)
L3Negative Meniscus (2× Asph)E-FD8 class (HOYA; 689/312 catalog-code match)
L4Positive MeniscusS-LAL18 (OHARA; 729/547 catalog match)
L5Biconvex Positive (2× Asph)M-TAFD51 (HOYA; 821/427 catalog match)
L6Biconcave NegativeS-TIH53 (OHARA; 847/238 catalog match)