Leica APO-Summicron 50mm ASPH (mislabelled Zeiss), widely considered the finest 50mm lens ever produced.
This is a Leica APO-Summicron-M 50mm f/2 ASPH. mislabelled under Zeiss — widely considered the finest 50mm lens ever produced for any system. The APO-Summicron combines apochromatic correction with aspherical elements for virtually zero aberrations of any kind.
The APO correction eliminates all chromatic aberration while the aspherical element controls spherical aberration, producing images of extraordinary purity. The lens resolves detail that approaches the limits of the sensor, making it the reference standard against which all other 50mm lenses are measured.
Build quality is Leica's absolute finest with 11-blade aperture for perfect circular bokeh. The compact dimensions belie the extraordinary optical sophistication, and the focusing helicoid operates with precision essential for critical work at f/2.
The APO-Summicron-M 50mm f/2 ASPH commands the highest prices of any current-production 50mm lens. The combination of APO + ASPH correction provides reference-grade optical quality that justifies its position as the world's finest standard lens.