PENTAX SMC D FA645 25mm f/4 AL[IF] SDM AW

US 8,422,143 B2 — Masakazu Saori

12 REFRACTIVE ELEMENTS / 7 MODELED GROUPS
f = 25.6946 mm (DESIGN)
F/4.1 (DESIGN)
2ω = 109.4°
3 ASPHERICAL SURFACES
INNER FOCUS

Focus Mechanism

CONSTRAINED_RECONSTRUCTION: patent-prescribed rigid R3–R7 inner-focus block moves 2.982301297 mm objectward at the official 0.4 m MFD; reconstruction was solved in the raw patent physical coordinates before OP-filter air-equivalent normalization and predicts 0.11241× magnification.

Optical Elements (12 physical)

ElementTypeGlass
F1Negative Meniscus835427 — coordinate class (vendor not established)
F2Neg. Meniscus (2× Asph)731405 — coordinate class (vendor not established)
F3Biconcave Negative618634 — coordinate class (vendor not established)
F4Biconvex Positive744449 — coordinate class (vendor not established)
F5Negative Meniscus835427 — coordinate class (vendor not established)
R1Biconvex Positive648338 — coordinate class (vendor not established)
R2Negative Meniscus773496 — coordinate class (vendor not established)
R3Biconvex Positive497816 — coordinate class (vendor not established)
R4Biconcave Negative806333 — coordinate class (vendor not established)
R5Biconvex Positive487704 — coordinate class (vendor not established)
R6Biconcave Negative835427 — coordinate class (vendor not established)
R7Biconvex Positive (1× Asph)589613 — coordinate class (vendor not established)