When mounted on the medium-format digital SLR camera body, this ultra-wide-angle lens offers a focal length equivalent of approximately 19.5 mm in the 35 mm format.
The lens incorporates two high-performance aspherical optical elements in its optics, delivering exceptional image-resolving power with outstanding brightness levels even at the edges, says the company, while compensating various aberrations to a minimum.
This lens is treated with Aero Bright Coating, which assures outstanding anti-reflection performance over a broader wavelength range, says Pentax, to deliver images that are more brilliant and in higher quality than those produced by previous models.
As the newest model of the AW (All Weather) series, this lens features a highly dependable dustproof, weather-resistant construction with 11 special seals to effectively prevent the intrusion of dust and water into the lens interior. By coupling this lens with the 645D body, Pentax assures a durable, reliable digital imaging system performing in demanding outdoor settings – even in rain or mist, or at locations prone to water splashes or spray.
The lens features a built-in, pull-out-type filter holder in its barrel. By placing the C-PL (circular polarizing) filter, included as an exclusive accessory, on this holder, the user can easily rotate the filter to obtain the desired polarizing effect.
Featuring an advanced SDM (Supersonic Direct-drive Motor) autofocus mechanism employing a supersonic motor installed inside the lens barrel, the lens assures smooth, quiet autofocus operation.
The lens also features a Quick-Shift Focus system for instant switching to manual-focus operation, after the subject is captured in focus by the AF system.