Leica APO Summicron-SL 50mm F2 ASPH lens review

Announced on 15 August 2019 (see our coverage here), the Leica APO Summicron-SL 50mm F2 ASPH is a relatively compact high-end lens for Leica SL cameras. Inside, the lens design is complex for a 50mm. However, it's designed for a digital sensor, so some prerequisites must be met. It has no less than 12 elements in total, with several AD (anomalous dispersion) elements to mitigate CA and fringing, plus three with aspherical surfaces to reduce SA and distortion. The lens also adopts what some call a "digital element," or a lens profile, to correct vignetting, distortion and CA, more as an afterthought in this case, as the lens is so well corrected optically. Profiles now are widely adopted for mirrorless cameras, principally for viewing a "baseline" image in-camera, but by extension, this extends to in-camera JPEGs as well, of course. This practice is not restricted to Leica by any means, as RAW files aren't meant for viewing directly, so some image parameters have to be applied