A new-generation Star-series lens, assuring high-contrast, high-resolution imaging even at image edges, and delivering clear, crisp images with minimal aberrations

This large-aperture standard zoom lens is the latest model of the new-generation Star (★) series, which is designed to provide the best possible image quality and accommodate the super-high-performance cameras of the future. Its newly designed optics assures greatly improved contrast and sharpness compared to previous models, while compensating various aberrations to a minimum and delivering sharp, clear images not only in the middle of the image field but at the edges. By incorporating one ED (Extra-low Dispersion) glass optical element, one anomalous dispersion glass optical element and two ED (Extra-low Dispersion) aspherical glass optical elements, it effectively minimizes chromatic aberration over the entire zoom range.

The newly designed zoom optics features a lighter, more compact focus-lens group. This focus-lens group is driven by an advanced PLM (Pulse Motor), which assures smooth, high-speed autofocus operation with minimized noise. A redesigned focus mechanism provides a minimum focusing distance of just 0.3 meters and a maximum magnification of 0.24 times, making this a handy lens for capturing all types of subjects — from everyday snapshots to close-ups and landscapes.

This lens features a KAF4 lens mount compatible with an electromagnetic diaphragm control system. Cameras compatible with this system are K-1 Mark II, K-1, K-3 Mark III, K-3 II, K-3, KP, K-70, K-S2, K-S1 and K-50. For K-1, K-3 II, K-3, K-S2, K-S1 and K-50, the camera’s firmware must be upgraded to the latest version.
If this lens is mounted on a camera without proper firmware upgrade, its diaphragm control mechanism becomes inactive, making it impossible to obtain correct exposure.

*Please apply the latest update of Digital Camera Utility 5 when you handle images taken by this lens on Digital Camera Utility 5. In case the software version is old, the name of this lens can not be displayed correctly. Digital Utility 4 and below can not display the name of this lens correctly.

Included Accessories: Lens Case S120-150, Lens Hood PH-RBN77, Lens Cap O-LC77, Lens Mount Cap K

Features / Specifications

A new-generation Star-series lens, perfected in pursuit of the ultimate in image quality
This standard zoom lens is a member of the new-generation Star (★) series, designed to provide the greatly improved resolving power that will be demanded by tomorrow’s super-high-performance cameras. It delivers high-contrast, high-resolution images across the image field, even at open aperture, while producing a smooth, natural bokeh (defocus) effect to assure true-to-life image renditions. The incorporation of a high-performance PLM (Pulse Motor) provides much improved autofocus performance in both speed and precision. Despite the large maximum aperture of F2.8, this standard zoom lens assures outstanding maneuverability and portability — the most distinguished features of lenses exclusively designed for use with APS-C-format digital cameras — to accommodate all types of applications, from scenic and nature photography to snap-shooting and portraiture.
Exceptional resolving power assured by uncompromising optical design
The 10-group, 16-element optical system (including four aspherical optical elements) assures superb resolving power and delivers super-clear, high-contrast images from the middle of the image field to the edges. By incorporating one ED (Extra-low Dispersion) glass optical element, one anomalous dispersion glass optical element and two ED (Extra-low Dispersion) aspherical glass optical elements, it reduces chromatic aberration to a minimum over the entire zoom range. The 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, effectively minimizes flare and ghost images even in demanding lighting conditions such as backlighting.

* HD stands for High Definition.

High-performance PLM for quiet, high-speed autofocus operation
The focus-lens elements are directly driven by a PLM (Pulse Motor), providing much-improved focusing speed (approx. 2.2 times faster in the wide-angle range, or approx. 1.5 times faster in the telephoto range, compared to the smc PENTAX-DA 16-50mm F2.8ED AL[IF] SDM),* while effectively minimizing noise for quieter operation. Manual-focus operation of the power-assisted focus mechanism has also been upgraded to optimize the precision and response of detecting the focus ring. As the result, the focus-lens elements shift more efficiently and flawlessly in synchronization with focus-ring operation.* When using AF.S mode for viewfinder shooting of still images, at a distance of 0.3 meters to infinity.

PLM unit diagram

  • Lead Screw
  • PLM (Pulse Motor)
  • Focus Lens
Electromagnetic diaphragm mechanism for flawless, high-precision exposure control during video recording
When mounted on a compatible KAF4-mount camera body,* this zoom lens assures flawless, high-precision exposure control, not only in still-image shooting, but also in video recording. Even when there are considerable differences in brightness during video shooting, its electromagnetic diaphragm control mechanism allows the user to capture video clips using automatic exposure control. In combination with some compatible cameras,** 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 recording. This means 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.

* Compatible KAF4-mount models are: PENTAX K-3 Mark III, PENTAX K-3 II, PENTAX K-3, PENTAX KP, PENTAX K-70, PENTAX K-50, PENETAX K-S2, PENTAX K-S1, PENTAX K-1 Mark II, and PENTAX K-1. We advise that users upgrade the camera’s firmware to the latest version to properly use electromagnetic diaphragm control. When mounted on the PENTAX K-1 Mark II or PENTAX K-1 camera body, images can only be captured in Crop mode, because the lens image circle is exclusively designed for the APS-C format.

** Models compatible with video recording in AF.C mode are: PENTAX K-3 Mark III, PENTAX K-70 and PENTAX KP. We advise that users upgrade the camera’s firmware to the latest version for optimum video recording performance.

Dustproof, weather-resistant construction
This lens features the “All Weather (AW)” construction to prevent the intrusion of dust and water into the lens interior. Pair it with a PENTAX dustproof, weather-resistant digital SLR camera body for creative shooting in rain or mist, or other locations prone to water splashes.

Other features
  1. Round-shaped diaphragm to produce a natural, beautiful bokeh (defocus) effect, while minimizing the streaking effect of point light sources
  2. SP (Super Protect) coating to keep the front surface free of dust and spots
  3. Quick-Shift Focus System for instant switching from autofocus to manual-focus operation, by holding the shutter-release button halfway down and turning the focus ring after the subject is captured in focus by the camera’s AF system.

Geometric optics MTF (MTF calculated without referencing the effects of light diffraction phenomenon)

Wave optical MTF (MTF calculated referencing the effects of light diffraction phenomenon)

Spatial Frequencies S:Sagittal M:Meridional
10 lines/mm
30 lines/mm

Focal length (Equivalent to 35mm format) 16-50mm
Equivalent to 24.5-76.5mm in 35mm format (when attached to PENTAX APS-C size DSLR cameras)
Maximum Aperture F2.8
Minimum Aperture F22
Lens construction 16 elements in 10 groups
Angle of View (Diagonal) 83-31.5°
(when attached to PENTAX APS-C size DSLR cameras)
Mount KAF4
Minimum Focusing Distance 0.3m (0.98ft.)
Maximum Magnification 0.24x
Filter Diameter 77mm
Diaphragm Control Electromagnetic diaphragm
Fully automatic
Number of Diaphragm Blades 9
Rounded diaphragm (16mm:F2.8-5.6 50mm:F2.8-8)
Aperture Ring N/A
Tripod Mount N/A
Lens Hood PH-RBN77 (included)
Lens Cap O-LC77 (included)
Lens Case S120-150 (included)
Maximum Diameter x Length approx. 84mm x 117mm (approx. 3.3in. x 4.6in.)
Weight approx. 712g / with hood approx. 750g
(approx. 25.1oz. / with hood approx. 26.5oz.)
Temperature -10°C~40°C (14°F~104°F)
Humidity 85% or less (no condensation)
Included Accessories Lens Hood PH-RBN77, Lens Cap O-LC77, Lens Mount Cap K, Lens Case S120-150
Others HD Coating
SP (Super Protect) Coating
AW (All Weather Resistant)
Quick-shift Focus System (QFS/M)
Pulse Motor

Compatible Converters