PENTAX SUPER-TAKUMAR 28mm f/3.5

US 3,506,339 — Tomokazu Kazamaki

7 ELEMENTS / 7 GROUPS
f = 28.000 mm
F/3.5
2ω = 74.5°
ALL-SPHERICAL

Focus Mechanism

Inferred unit-focus model: the complete seven-element assembly translates rigidly because the patent publishes no variable internal spacing.

Optical Elements (7 physical)

ElementTypeGlass
L1Positive MeniscusS-BAH10 (OHARA equivalent; patent supplier not specified)
L2Negative MeniscusS-BSM16 (OHARA equivalent; patent supplier not specified)
L3Positive Meniscus (Near-Zero Power)N-LAK7 (SCHOTT equivalent; patent supplier not specified)
L4Biconvex PositiveS-LAM58 (OHARA exact 720/420 match; patent supplier not specified)
L5Biconcave NegativeE-FD15 (HOYA equivalent; patent supplier not specified)
L6Positive MeniscusS-BSM16 (OHARA equivalent; patent supplier not specified)
L7Positive MeniscusS-BSM16 (OHARA equivalent; patent supplier not specified)