Super Rokkor 50mm f1.8 - optical design
Super Rokkor 50mm f1.8 - optical design
The Super Rokkor 50mm f1.8 lens has a 6-element, 5-group Planar-type design. Compared to the Zeiss Planar, the first cemented group in the Super Rokkor is split. See the attached scans, which include the cover from the Japanese-language book.
This configuration, with wide variations in geometries, was used by other lens makers for fast 50's and short teles. Six-element, 5-group Plane-types with a split second cemented pair were also common (Fujinon 50mm f2, for example). I don't know who came up with these Planar variations first, but I'm sure the idea to do so occurred to many. When it comes optical designs, it's usually safe to assume Carl Zeiss did it first.
Cheers,
David