The Leica Super-APO-Summicron-SL 21 mm F2 ASPH is a high-speed wide-angle for Leica SL cameras. It was announced in October 2023. This lens has the Super-Apo moniker and has a complex design of 14 elements in total, arranged in 11 groups. Leica doesn’t say how many AD (anomalous partial dispersion) elements there are but claims that ‘most’ of the 14 elements are made from ‘special custom glass.’ That may include the three elements with aspherical surfaces, but it’s unclear. Like others in the SL range, the lens also adopts a ‘digital element,’ or what’s better known as a built-in profile, to correct vignetting, distortion and chromatic aberration. While it’s perhaps…