CARL ZEISS JENA SONNAR 50mm f/1.5

US 1,975,678 — Ludwig Bertele

7 ELEMENTS / 3 GROUPS
f ≈ 50.2 mm
F/1.5
2ω ≈ 42° (patent)
ALL SPHERICAL

Focus Mechanism

Inferred unit focus — all elements and the stop move objectward 3.15 mm at the modeled 0.90 m object-to-image endpoint. No focus schedule is published; intermediate distance labels are approximate.

Optical Elements (7 physical)

ElementTypeGlass
L1Positive MeniscusUnmatched (supplier unspecified; patent nd=1.6375, νd=56.1)
L2Positive MeniscusUnmatched (supplier unspecified; patent nd=1.6727, νd=47.3)
L3Biconvex PositiveUnmatched (patent ultra-low-index crown, nd=1.4075, νd=65.7; no practical catalog glass)
L4Biconcave NegativeN-SF8 equivalent (catalog comparison; supplier unspecified, patent nd=1.6890, νd=31.0)
L5Negative MeniscusUnmatched (supplier unspecified; patent nd=1.5481, νd=45.9)
L6Biconvex PositiveUnmatched (SSK51-class very dense crown, near N-SSK5; patent nd=1.6578, νd=51.2)
L7Negative MeniscusUnmatched (supplier unspecified; patent nd=1.5488, νd=63.0)