Sonnar2
Well-known
Not only the Japanese lens maker published the diagrams, but it looks like some made more effort with patent protection than others. Zeiss has most, LEICA some, Canon less, NIKON and Pentax havn't many patents on lenses. After all you need a lot more information, glass type and stuff, to copy a lens as just diagrams. Even the patent diagrams don't include all information, i.e. hide enlargement of front elements in order to increase edge illumination (less light falloff). 62mm is a good filter size. The Canon has 72mm. Noctilux 1/50 has 60, and light-falloff is quite visible.
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