OLYMPUS ZUIKO AUTO-MACRO 50mm f/2

US 4,708,445 — Hisashi Goto

9 ELEMENTS / 7 GROUPS
f ≈ 50.0 mm
F/2.0
2ω ≈ 45.6°
ALL SPHERICAL

Focus Mechanism

Floating element: entire lens advances while the air gap between Group I (L1+L2) and Group II (L3+L4) increases, maintaining aberration correction from infinity to 1:2 magnification.

Optical Elements (9 physical)

ElementTypeGlass
L1Negative MeniscusF5 (603/380)
L2Biconvex PositiveS-LAL18 (OHARA; 729/547)
L3Positive MeniscusN-LAF34 (Schott catalog-equivalent to patent 773497; supplier not identified)
L4Negative MeniscusPBL25 (OHARA, 581408)
L5Biconcave NegativeBAF22 (HOYA catalog-equivalent; production supplier unspecified)
L6Biconvex PositiveS-LAM61 (OHARA, 720460)
L7Positive MeniscusN-LAF34 (Schott catalog-equivalent to patent 773497; supplier not identified)
L8Biconvex PositiveN-LAF34 (Schott catalog-equivalent to patent 773497; supplier not identified)
L9Negative MeniscusSF4 (755/275)