Summicron 35mm f/2 (v1)

Leitz introduced the 35mm focal length to the M system in 1958 with a bold optical prescription: eight elements arranged in a double-Gauss variant, unusual complexity for an f/2 lens. The extra glass allowed the designers to control field curvature and distortion simultaneously, producing an image plane that is remarkably flat across the frame while retaining a subject "pop" that photographers describe as three-dimensional. Stopped down to f/5.6 it rivals clinical modern lenses; wide open at f/2 it renders with unmistakable character.

For beginners: "eight element" simply refers to the number of individual glass pieces inside the lens. More elements is not always better — each surface can introduce flare — but in this design the extra elements earn their keep. The v1 was made in both M-mount and a rare goggle version for the M3's 0.91x finder; the goggle version commands a collector premium but is optically identical. Clean examples are genuinely usable everyday lenses, not just shelf ornaments.