This ultra-wide-angle lens not only features PENTAX-original optics optimized for high-quality digital photography to assure exceptional image-description performance, but also offers a dependable dust-proof, weather-resistant construction for active outdoor photographers. The first unifocal, ultra-wide-angle lens for the PENTAX 645D When mounted on the PENTAX 645D camera body, this ultra-wide-angle lens offers a focal length of 19.5mm in the 35mm format, providing the widest perspective of all PENTAX 645 interchangeable lenses. Creating visual effects unique to ultra-wide-angle lenses — such as exaggerated perspective & extra-wide depth of field — it can be effectively used for a wide range of subjects & situations, including spectacular landscapes & indoor shooting in confined spaces. It assures greater freedom & flexibility in high-quality, medium-format digital SLR photography. State-of-the-art optics Incorporating two high-performance aspherical optical elements in its optics, this ultra-wide-angle lens provides exceptional image-resolving power with outstanding brightness levels even at the edges, while compensating various aberrations to a minimum. All lens characteristics are optimized for digital photography: for instance, exclusive lens coatings are applied to optical elements, while anti-reflection materials are applied to the interior of the lens barrel. The result is a lens that brings out the full potential of the PENTAX 645D medium-format digital SLR camera. Aero Bright Coating This lens is treated with PENTAX-original Aero Bright Coating, which assures an outstanding anti-reflection performance over a broader wavelength range to deliver images that are more brilliant & in higher quality than those produced by previous models. Born as the fruit of PENTAX’s advanced nanotechnology, this exclusive coating effectively reduces lens reflectance & greatly increases light transmittance by forming a silica aerogel layer with uniform pores on the surface of optical elements. Dependable dustproof, weather-resistant construction As the newest model of the dependable “AW” (All Weather) series, the lens features a highly dependable dustproof, weather-resistant construction with 11 special seals to effectively prevent the intrusion of dust & water into the lens interior. By coupling this lens with the PENTAX 645D camera body, the user is assured of a durable, reliable digital imaging system that performs superbly in demanding outdoor settings — even in rain or mist, or at locations prone to water splashes or spray. Mountable Circular Polarizing Filter The lens features a built-in, pull-out-type filter holder in its barrel. By placing the C-PL (circular polarizing) filter (40.5mm in diameter; included as an exclusive accessory) on this holder, the user can easily rotate the filter to obtain the desired polarizing effect.