Convenient mid-range zoom with a fixed f/2.8 aperture through entire zoom range.. Light & compact everyday carry lens. Newly designed Image Stabilization unit allows for lighter and smaller lens build.. Incredible quality from edge-to-edge due to 2 UD elements to minimize chromatic aberration, and 2 aspheric lenses.. Impressive durability and weather-resistant construction equivalent to an L-series lens for use in harsh environments.