When the announcement of Sigma’s new 18–35mm lens arrived, some of our staffers chuckled upon opening the e-mail. Why? Because of what appeared to be a typo in the headline: Instead of f/2.8, it quoted f/1.8 as the maximum aperture! But as we read further, we learned the joke was on us: The lens is the industry’s first f/1.8 constant-aperture zoom, and thus the fastest. It comes in mounts for Canon, Nikon, Pentax, Sigma, and Sony DSLRs.