HD PENTAX-DA645 28-45mm f/4.5 ED AW SR

JP 2015-87681 A — Tatsuyuki Onozaki

17 PHYSICAL LENSES / 12 GROUPS
28-45mm f/4.5 MARKETED
28.699-43.874mm DESIGN
f/4.6 MODELED DESIGN APERTURE
2 ED ELEMENTS
2 HYBRID ASPHERICAL ELEMENTS / 2 ASPHERICAL SURFACES
CONSTRAINED G2a INNER-FOCUS RECONSTRUCTION

Focus Mechanism

CONSTRAINED_RECONSTRUCTION. Patent paragraph 0052 identifies positive G2a (L21-L23) as the focus group and states that it moves imageward, but publishes no close-focus spacing row. A code solve at the production 0.4 m MFD translates G2a imageward by 4.336536 / 4.352598 / 4.497008 mm at wide / middle / tele; d9 increases and d14 decreases equally, conserving the G2 envelope. The tele paraxial magnification is 0.206291x, consistent with the rounded marketed 0.21x. These close states are reconstructed, not patent-published.

Optical Elements (17 physical; 19 modeled media)

ElementTypeGlass
L11gNegative Meniscus Substrate, convex to objectS-LAH66N (OHARA catalog model; supplier not established)
L11rBonded Hybrid Asphere Resin LayerUnmatched (synthetic resin hybrid-asphere layer, nd=1.52972, vd=42.7)
L12Negative Meniscus, convex to objectS-LAH64 (OHARA catalog model; supplier not established)
L13Biconcave NegativeS-PHM53 (OHARA catalog model; supplier not established)
L14Biconvex PositiveS-TIL26 (OHARA catalog model; supplier not established)
L21Positive Meniscus, convex to objectS-TIL26 (OHARA catalog model; supplier not established)
L22Negative Meniscus, convex to objectS-NBH55 (OHARA catalog model; supplier not established)
L23Biconvex PositiveS-TIL25 (OHARA catalog model; supplier not established)
L24Biconvex PositiveS-FPL51 (OHARA catalog model; supplier not established)
L31Biconcave NegativeS-LAH55VS (OHARA catalog model; supplier not established)
L32Biconvex PositiveS-NBH 8 (OHARA catalog model; supplier not established)
L33Biconcave NegativeS-LAH60 (OHARA catalog model; supplier not established)
L34Positive Meniscus, convex to objectS-TIH 6 (OHARA catalog model; supplier not established)
L41Biconvex PositiveS-LAH60 (OHARA catalog model; supplier not established)
L42Biconcave NegativeS-LAH63Q (OHARA catalog model; supplier not established)
L43Biconvex PositiveS-FPL51 (OHARA catalog model; supplier not established)
L44rBonded Hybrid Asphere Resin LayerUnmatched (synthetic resin hybrid-asphere layer, nd=1.52972, vd=42.7)
L44gBiconcave Negative SubstrateS-LAH60 (OHARA catalog model; supplier not established)
L45Biconvex PositiveS-FSL 5 (OHARA catalog model; supplier not established)