NIKON Gyogyotto 20mm f/8 — Optical Cross-Section & Ray Tracing

Home / Lenses / Nikon / NIKON Gyogyotto 20mm f/8NIKON Gyogyotto 20mm f/8US 5,949,588 Table 8 — Ohshita / Shibayama
3 elements / 2 groups
f = 20.0 mm (scaled from patent f = 100)
f/8 marketed; f/8.25 design
2ω = 164.0° patent field
all-spherical
Focus MechanismFixed-focus production lens. The patent notes optional whole-lens extension or L1-only focusing, but Table 8 provides no close-focus spacing data.
Optical Elements (3)ElementTypeGlass
L1Plano-Concave NegativeN-SK16 / S-BSM16 class (620/601; patent νd=60.14)
L2Thick Negative MeniscusN-SF6 / S-TIH6 class (805/254)
L3Biconvex Positive670575 — Nikon patent glass (nd=1.67025, νd=57.53; no current public OHARA/SCHOTT catalog match within tolerance)
AnalysisDetailed analysis available in the interactive viewer above.

Element	Type	Glass
L1	Plano-Concave Negative	N-SK16 / S-BSM16 class (620/601; patent νd=60.14)
L2	Thick Negative Meniscus	N-SF6 / S-TIH6 class (805/254)
L3	Biconvex Positive	670575 — Nikon patent glass (nd=1.67025, νd=57.53; no current public OHARA/SCHOTT catalog match within tolerance)