Leica Super Wide Angle 21mm f/2.8 Elmarit M Aspherical Manual Focus Lens (6-Bit, Updated for Digital) - Black USA

This lens is distinguished by uniform sharpness and minimal distortion across the entire image area even at full aperture. This was achieved with, among other factors, a lens element with an aspherical surface. The lens makes highly dramatic effects possible, like monumental foregrounds, strongly receding backgrounds and a wide horizon. With this lens, focusing and metering are performed by looking through the camera's viewfinder, while the actual framing is checked with an accessory viewfinder #12008 that mounts in the camera's hot-shoe.

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).