Sigma surprised pretty much everyone by announcing a new zoom lens for APS-C digital cameras, the Sigma 18-35mm f/1.8 DC HSM lens. This represents a new milestone in zoom lenses, as no one has ever made a constant aperture f/1.8 zoom lens for this format before now. Professional-class zoom lenses have topped out at f/2.8 for most manufacturers until this introduction, although Olympus made some high quality zoom lenses for the standard 4/3s format with an aperture of f/2. With the new Sigma 18-35mm f/1.8, the range is somewhat limited (in 35mm equivalent terms, this is a 27-52.5mm lens), but this lens will reach new heights in limited depth of field for a zoom lens and could conceivably replace several lens in a photographer's bag. This is also part of Sigma's "A" series lenses, which stands for "Art," so we can expect smooth bokeh and high resolution. The lens features 17 elements in 12 groups, a fairly complicated design, with 4 glass-molded aspherical elements and 5 Special Low Dispersion (SLD) elements. Lately, Sigma has been on a roll and this is a lens to look forward to. Kudos to Sigma! Makes you wonder what else they have up their sleeves.
