RUSSAR-21 60mm f/18

US 2,516,724 A — Michael Michaelovitch Roossinov

6 ELEMENTS / 4 GROUPS
f = 59.426 mm
F/17.929
133° PUBLISHED FIELD
ALL SPHERICAL

Focus Mechanism

Fixed patent prescription at infinity; no finite-focus movement is modeled.

Optical Elements (6 physical)

ElementTypeGlass
L1Negative MeniscusUnmatched (Lenzos L-67; nd=1.6395, vd=43.3; reference wavelength unstated)
L2Biconvex PositiveBACD4 spectral proxy (Lenzos L-24 / historical SK4 class; production melt unresolved)
L3Biconcave NegativeLLF1 spectral proxy (Lenzos L-28; production melt unresolved)
L4Biconcave NegativeLLF1 spectral proxy (Lenzos L-28; production melt unresolved)
L5Biconvex PositiveBACD4 spectral proxy (Lenzos L-24 / historical SK4 class; production melt unresolved)
L6Negative MeniscusH-BaF8 spectral proxy (Lenzos L-15 / historical BaSF1 class; production melt unresolved)