NIKON AF-S DX MICRO-NIKKOR 40mm f/2.8G

US 2011/0170195 A1 — Mami Muratani, Issei Tanaka

PATENT: 9 ELEMENTS / 8 GROUPS
PRODUCTION: 9 ELEMENTS / 7 GROUPS
40 mm MARKETED / 40.001 mm MODELED
f/2.8 MARKETED / f/2.68 MODELED
38°50′ MARKETED / 39.0° PATENT FIELD
1 ASPHERICAL SURFACE / 1:1 PUBLISHED CLOSE STATE

Focus Mechanism

PUBLISHED: Example 1 supplies INF, β=-0.5 MID, and β=-1.0 CLD states. G1 and G2 move objectward while d1a changes; the stop co-moves with G2, d1b stays 4.00000 mm, and G3 remains fixed to the physical image plane. Runtime focus uses one linear parameter between the published INF/CLD endpoints, so the published MID d1a/d2 pair is verified separately and is not represented exactly by the runtime interpolation. The modeled CLD conjugate is 0.15264661 m object-to-physical-focal-plane, while closeFocusM retains Nikon's separate 0.163 m marketed minimum-focus specification.

Optical Elements (9 physical)

ElementTypeGlass
L11Negative Meniscus (concave to image)FK5 (SUMITA catalog equivalent; production supplier unspecified)
L12Biconvex PositiveNBFD13 (HOYA catalog correlation; patent vendor unspecified)
L13Biconvex PositiveBACD4 (HOYA catalog correlation; patent vendor unspecified)
L14Biconcave NegativeF3 (SUMITA catalog equivalent; production supplier unspecified)
L21Biconcave NegativeF3 (SUMITA catalog equivalent; production supplier unspecified)
L22Biconvex PositiveN-SK16 (SCHOTT catalog equivalent; production supplier unspecified)
L23Biconvex Positive (rear asphere)M-PCD4 (HOYA catalog correlation; patent vendor unspecified)
L31Negative Meniscus (concave to image)FK5 (SUMITA catalog equivalent; production supplier unspecified)
L32Positive Meniscus (concave to object)J-LAF2 (HIKARI catalog equivalent; production supplier unspecified)