To give the "M" system even greater versatility in difficult light situations, the popular Leica Summicron-M 28mm f/2.0 Aspherical Lens (6-bit, manual focus) has a focal length with an even faster speed of others in the line of Leica Summicron high speed lenses. By means of a complex optical computation, the use of special types of optical glasses and the inclusion of a lens element with an aspherical surface, it has been possible to create a lens with outstanding performance that is in no way below that of the excellent performance of the Elmarit-M 28 f/2.8. Considering the fact that this lens is one stop faster than the 28 f/2.8, it is remarkable that the designers were able to keep the dimensions and weight of the new lens virtually the same as the old lens. This lens features outstanding image performance across the entire field, high resolving power and brilliance even at maximum aperture.
This lens has been updated with the "6-bit" coding, which allows the digital M camera to read this information optically and to identify which lens is being used. The camera can then (optionally) apply a "final stage" software based vignetting correction (for RAW images the lens used is simply recorded, no change is made).