Leica Tri Elmar M 4/16-18-21 Asph

With its impressive angle of view of 107°, this new TRI-ELMAR conquers 16 mm super wide-angle photography in perfect Leica M style. Due to the minimal distortion and barely perceptible field curvature, it can be recommended for highly demanding architecture photography even at the 16 mm setting. Used on the digital M8, it produces the image effect of a 21 - 28 mm lens, still enabling extreme wide-angle views. The ultra compact shape is achieved by two aspherical elements. A new design of the interior focusing significantly enhances the quality in the close-focus range through an adaption of the floating element principle. Brilliant field depth can therefore be used from a distance of 0.33 m for hyperfocal photography. 

For more info: http://us.leica-camera.com/Photography/Leica-M/M-Lenses/Tri-Elmar-M-16-18-21mm-f-4-ASPH