SIGMA 24mm f/1.8 EX DG ASPHERICAL MACRO — Optical Cross-Section & Ray Tracing

Home / Lenses / Sigma / SIGMA 24mm f/1.8 EX DG ASPHERICAL MACROSIGMA 24mm f/1.8 EX DG ASPHERICAL MACROJP 2001-330771 A↗ — Shizuka Takemoto, Norikazu Yokoi
10 ELEMENTS / 9 GROUPS
DESIGN f = 24.69 mm
DESIGN F/1.85
2 HYBRID ASPHERICAL SURFACES / 2 ELEMENTS
INFINITY FOCUS ONLY
Focus MechanismInfinity focus only; every air gap stays fixed. The patent describes floating focus: G1 (G1a–G1c) and G2 (G2a–G2c, with the stop) both move toward the object, G1 by 0.62 times the travel of G2, so the gap d11 ahead of the stop narrows. It tabulates one near state: d11 = 2.30 mm (5.96 mm at infinity) at OBJ = 50, read as an object 50 mm ahead of the first surface, about 1:2.6. That state is not modeled because the patent prints no image distance for it. The 38.58 mm image distance at infinity is the paraxial back focus of the printed table; the patent prints no back focus. The production lens focuses to 0.18 m (1:2.7); that is product data, not modeled focus travel.
Optical Elements (10 physical; 12 modeled media)ElementTypeGlass
L1Positive MeniscusBAFD8 (HOYA) / S-BAH28 (OHARA) coordinate-equivalent class; supplier unconfirmed
L2Negative MeniscusNBFD10 (HOYA coordinate-equivalent class; supplier unconfirmed)
R1Hybrid Resin Negative Meniscus (1× Asph)Unmatched (hybrid optical resin; spectrum unpublished)
L3Negative MeniscusS-LAH51 (OHARA coordinate-equivalent class; supplier unconfirmed)
L4Biconvex PositiveS-TIH6 (OHARA coordinate-equivalent class; supplier unconfirmed)
L5Positive MeniscusNBFD10 (HOYA coordinate-equivalent class; supplier unconfirmed)
L6Biconvex PositiveLAC8 (HOYA coordinate-equivalent class; supplier unconfirmed)
R2Hybrid Resin Positive Meniscus (1× Asph)Unmatched (hybrid optical resin; spectrum unpublished)
L7Positive MeniscusK-LaK14 (SUMITA coordinate-equivalent class; supplier unconfirmed)
L8Biconcave NegativeS-TIH4 (OHARA coordinate-equivalent class; supplier unconfirmed)
L9Positive MeniscusLAC8 (HOYA coordinate-equivalent class; supplier unconfirmed)
L10Biconvex PositiveUnmatched (native 1.60625/63.1; no compatible catalog coordinate)

Element	Type	Glass
L1	Positive Meniscus	BAFD8 (HOYA) / S-BAH28 (OHARA) coordinate-equivalent class; supplier unconfirmed
L2	Negative Meniscus	NBFD10 (HOYA coordinate-equivalent class; supplier unconfirmed)
R1	Hybrid Resin Negative Meniscus (1× Asph)	Unmatched (hybrid optical resin; spectrum unpublished)
L3	Negative Meniscus	S-LAH51 (OHARA coordinate-equivalent class; supplier unconfirmed)
L4	Biconvex Positive	S-TIH6 (OHARA coordinate-equivalent class; supplier unconfirmed)
L5	Positive Meniscus	NBFD10 (HOYA coordinate-equivalent class; supplier unconfirmed)
L6	Biconvex Positive	LAC8 (HOYA coordinate-equivalent class; supplier unconfirmed)
R2	Hybrid Resin Positive Meniscus (1× Asph)	Unmatched (hybrid optical resin; spectrum unpublished)
L7	Positive Meniscus	K-LaK14 (SUMITA coordinate-equivalent class; supplier unconfirmed)
L8	Biconcave Negative	S-TIH4 (OHARA coordinate-equivalent class; supplier unconfirmed)
L9	Positive Meniscus	LAC8 (HOYA coordinate-equivalent class; supplier unconfirmed)
L10	Biconvex Positive	Unmatched (native 1.60625/63.1; no compatible catalog coordinate)