The lens optics incorporates four ED (Extra-low Dispersion) glass and one Super ED (Extra-low Dispersion) glass optical elements to minimize chromatic aberration and prevent color bleeding, not only in the main in-focus area, but also in the surrounding defocused areas.
It also features a large-aperture negative meniscus optical element, a biconvex aspherical glass-mold optical element, and a high-refraction glass optical element in the first lens group, to reduce the overall size despite the ultra-wide-angle design, while delivering outstanding imaging performance for sharp, crisp images without fuzziness, even in the peripheral areas. The lens also features PENTAX-original HD Coating.
This lens incorporates an electromagnetic diaphragm mechanism (lens features the KAF4 mount, and is compatible with electromagnetic diaphragm control) to assure high-precision exposure control when used in combination with compatible digital SLR cameras. It 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 sunray.
For use in demanding conditions -- such as at waterfronts or in sudden rainfall -- the lens features a dependable weather-resistant construction. By pairing it with a PENTAX weather-resistant digital SLR camera body, the user can create a highly dependable, airtight digital imaging system that performs superbly even in the most demanding shooting locations -- in rain or mist, or at locations prone to splashing water.
- SP (Super Protect) Coating to keep the lens front surface free of dust or stains.
- Built-in motor to drive the AF mechanism for smooth, quiet autofocus operation.
- Eight-blade circular diaphragm to produce beautiful light beams with point light sources, while creating a natural, beautiful bokeh (defocus) effect at open and larger apertures.
- QFS/A (Quick-Shift Focus System) for instant shift to the manual-focus mode without requiring focus-mode switching operations, after the subject has been captured in focus by the camera's autofocus system.