Summilux-M 35mm f/1.4 Aspherical

In 1990 Leica built a 35mm f/1.4 with two aspherical elements — each surface individually ground and polished by hand, a process so slow and failure-prone that the lens was effectively unmanufacturable at scale. Production ended around 2,000 units, replaced in 1994 by a redesign needing only one molded aspherical surface.

The community calls it the "AA" or "double aspherical" (双非 in Chinese collector circles). Because so few exist and the rendering combines pre-ASPH character with aspherical control, it trades at five-figure prices and sits near the top of every M-lens grail list alongside the Steel Rim and Noctilux 50/1.2.