" 1. Star series lens, designed for optimal image quality Designed as a member of the new-generation Star-series series — which provides the greatly improved resolving power that will accommodate the super-high-performance digital cameras of the future — this standard zoom lens compensates various aberrations to a minimum and delivers sharp, clear images, not only in the middle of the image field but at the edges. Incorporating one ED (Extra-low Dispersion) glass optical element, one anomalous glass optical element and two ED (Extra-low Dispersion) aspherical glass optical elements, it effectively reduces chromatic aberration to a minimum over the entire zoom range. Coupled with high-grade, multi-layer HD Coating,* which reduces the average reflectance in the visible ray spectrum to less than 50% that of conventional multi-layer coatings, it effectively minimizes flare and ghost images even in demanding lighting conditions such as backlighting. This standard zoom lens delivers exceptionally high resolving power and outstanding contrast even at open aperture, while capturing beautiful images with a smooth transition of the bokeh (defocus) effect and a true-to-life depth of field. Since its maximum aperture is fixed at F2.8 over the entire focal-length range from 16 to 50 millimeters (equivalent to 24.5mm to 76.5mm in 35mm format), this large-aperture zoom lens makes it an ideal regular-use lens for the PENTAX K-3 Mark III. 「HD」= High definition 2. High-speed AF, minimum focusing distance 0.3m This zoom lens incorporates a newly designed optical system which features a lighter, more compact focus-lens group. By driving this focus-lens group with an advanced PLM (Pulse Motor), it assures smooth, high-speed autofocus operation with minimized operational noise. Thanks to the redesigned focus mechanism, it provides the minimum focusing distance of just 0.3 meters, and the maximum magnification of 0.24 times, making this a handy, regular-use lens for capturing all types of subjects — from everyday snapshots to close-ups and landscapes. 3. Electromagnetic diaphragm mechanism for high-precision diaphragm control This zoom lens features an electromagnetic diaphragm control mechanism* to assure high-precision exposure control when used in combination with compatible digital SLR cameras. It also lets the user capture video clips using automatic exposure control, even when there are considerable differences in brightness during the video shooting. When mounted on a PENTAX K-3 Mark III, PENTAX KP or PENTAX K-70 camera body, the PLM (Pulse Motor) assures smooth focus tracking operation and flawless exposure control, while considerably reducing annoying noise generated by focus and diaphragm control operations during video shooting. Its assures smooth, worry-free video shooting in locations prone to considerable brightness changes — such as a stage with rapidly changing lighting conditions, or a forest with filtering sunrays — or with active, fast-moving subjects such as athletes or animals. The lens features the KAF4 mount, and is compatible with electromagnetic diaphragm control. Electromagnetic diaphragm control is available in combination with PENTAX K-3 Mark III, PENTAX K-3 II, PENTAX K-3, PENTAX KP, PENTAX K-70, PENTAX K-50, PENTAX K-S2, PENTAX K-S1, PENTAX K-1 Mark II or PENTAX K-1 camera bodies. We advise that users upgrade the camera's firmware to the latest version to properly use electromagnetic diaphragm control. When mounted on a PENTAX K-1 Mark II or PENTAX K-1 camera body, images can be captured only in Crop mode, because the camera's image circle is exclusively designed for the APS-C format. 4. Dust-proof / weather-resistant construction Developed as an AW (All Weather) model, this zoom lens features a dustproof, weather-resistant construction to prevent the intrusion of water and dust particles into the lens interior. By pairing it with a PENTAX dustproof, weather-resistant digital SLR camera body, the user can create a highly durable, reliable digital imaging system that performs superbly even in the most demanding shooting conditions — in rain or mist, or at locations prone to splashing water. 5. Other (1) Effortless manual-focus operation, with limited lens extension during focusing between the minimum focusing distance and infinity and optimum focus-ring torque (2) Nine-blade circular diaphragm to produce a natural, beautiful bokeh (defocus) effect (from open aperture to F5.6 in the wide-angle range; from open aperture to F8 in the telephoto range), while minimizing the streaking of point light sources ③ Quick-Shift Focus System to provide an instant shift to manual-focus operation, after locking the subject in focus during AF operation by pressing the camera's shutter-release button halfway down; this system can be used at any time during AF operation ④ SP (Super Protect) Coating to keep the lens front surface free of dust and stains"