Canon today announced a prototype Canon EF 400mm f/4 DO IS USM lens, the prototype will be shown at Photokina 2000 (which we will attend) in Cologne, Germany, from Sept 20 - 25. A full commercial version of the lens should be available in the first half of 2001. Diffractive optical elements use a diffraction grating to alter the light path, this new 400mm lens is significantly smaller and lighter (almost 1 KG) than Canon's current 400mm f/4.