PENTAX SMC DA 18-55mm f/3.5-5.6 AL

US 7,307,794 B2 — Masakazu Saori

12 ELEMENTS / 9 GROUPS
18-55mm f/3.5-5.6 (marketing)
Design f = 19.10-55.16 mm
2ω = 75.8°-28.6°
1 ASPHERICAL SURFACE
0.25 m MFD

Focus Mechanism

CONSTRAINED_RECONSTRUCTION: the patent focuses with G1 but publishes no close-focus row. At each zoom endpoint, only G1 is translated objectward to a 0.25 m image-plane-referenced object distance; G2-G4 and IMG remain fixed. Solved G1 travel is 4.590939 mm at wide and 4.532077 mm at tele.

Optical Elements (12 physical)

ElementTypeGlass
L11Negative Meniscus603607 class (SK/BACD family; patent vendor unspecified)
L12Negative Meniscus623582 class (OHARA S-BSM15 optical position; patent vendor unspecified)
L13Neg. Meniscus (1x Asph)Unmatched (nd=1.52538, vd=56.3; code position 525563)
L14Positive Meniscus847238 class (dense-flint family; patent vendor unspecified)
L21Biconvex PositiveUnmatched (nd=1.51601, vd=49.9; code position 516499)
L22Biconvex Positive487702 class (OHARA S-FSL5 optical position; patent vendor unspecified)
L23Negative MeniscusUnmatched (nd=1.84333, vd=24.2; code position 843242)
L31Positive Meniscus847240 class (nearest current family 847238; patent vendor unspecified)
L32Biconcave Negative773496 class (lanthanum-flint family; patent vendor unspecified)
L41Biconvex PositiveUnmatched (nd=1.64118, vd=58.9; code position 641589)
L42Biconvex PositiveUnmatched (nd=1.51601, vd=50.6; code position 516506)
L43Negative Meniscus756288 class (nearest current dense-flint family 755275/276; patent vendor unspecified)