Offering a 2X zoom ratio covering the 150mm to 300mm telephoto ranges (equivalent to approximately 90mm to 180mm in the 35mm format), this compact, lightweight zoom lens is ideal for a wide variety of telephoto applications, including portraits and casual snapshots. Consisting of 15 elements in 13 groups, this versatile telephoto zoom lens features ED (Extra-low Dispersion) lens elements to assure true-to-life image reproduction with minimal chromatic aberration. Its IF (Inner Focus) mechanism not only reduces the overall weight, but also improves autofocus speed and weight distribution during shooting. It also features a minimum focusing distance of 2 meters (6.6 feet) with a maximum magnification of 0.18 times. This telephoto zoom lens can also be used with the PENTAX 645 camera in manual-focus operation.