Leica 24mm F2.8 Elmarit  Asph. Superb Correction with Virtually No Distortion Very 3-Dimensional Images Wide Persepctive of 84 Degrees Accessory 24mm Viewfinder is Required A Relatively new lens with an Easier to Use Focal Length than the 21mm (more foregiving for compositional errors)   7 Elements in 5 Groups 1 Aspherical Filter Size is 55mm Snap on Hood & Cap included Apertures from F2.8 to F16 with clicks at half stops Focuses from .7 Meter to Infinity Only available in Black Wide Perspective, Great for Buildings, Architecture, Interiors, All Scenics/Landscapes, Street Scenes & Photojounalism