Distinguishing itself among most zooms, this 180-400mm features a built-in 1.4x teleconverter to allow for on-the-fly switching to an effective 252-560mm f/5.6 lens for greater reach. A constant f/4 maximum aperture is also a key feature for realizing consistent illumination throughout the zoom range and for producing shallow depth of field and selective focusing imagery. Complementing these traits is a sophisticated optical design that utilizes eight extra-low dispersion glass elements and one fluorite element to control chromatic aberrations and color fringing for increased clarity. Nano Crystal and Super Integrated Coatings have also been applied to individual elements to reduce flare and ghosting for greater contrast and color accuracy when working in strong lighting conditions.
Balancing the optical merits, this 180-400mm is also characterized by its inclusion of a Vibration Reduction image stabilization system that compensates for four stops of camera shake to enable sharper handheld shooting. A Silent Wave Motor also benefits producing sharp imagery, and affords quick and quiet autofocus performance along with full-time manual focus override. As a lens intended for use in trying conditions, it is weather-sealed and features a fluorine coating on the front element to resist fingerprints and smudging. Additionally, a removable, rotating tripod collar is included to assist working with a support system and this lens utilizes an electromagnetic diaphragm to ensure consistent exposure stability when shooting at fast continuous speeds.