"Sigma Corporation is pleased to announce the launch of the ten DG EX telephoto lenses. Recently, the demand for digitally optimized lenses increases rapidly as digital single lens reflex camera increases its market share. Sigma Corporation has started production of wide-angle lens DG series in 2000 and the number of DG series reached to thirteen models as of February 14, 2005. This time ten new EX telephoto lenses including three single focus telephoto lenses (APO 300mm F2.8 EX, APO 500mm F4.5 EX APO 800mm F5.6 EX) will be introduced to market as DG lens series, which demonstrates high performance with digital single, lens reflex cameras."Sigma has optimized their lens for use with digital SLR. The linked story mentions that there are no details as to exactly what that means. :? So is this just a branding thing or can a lens be optimized for a digital SLR?