The 12mm f/2.8 ED AS NCS Fisheye Lens for Pentax K Mount from Samyang provides a 180o diagonal angle of view on full-frame cameras for an ultra-wide angle, distorted perspective that is useful for architectural interiors, landscapes and creative experimentation in any photographic application. The f/2.8 maximum aperture is effective in low-light situations and enables some measure of shallow depth of field control. The lens's sophisticated optical design consists of 12 lens elements arranged in 8 groups including three elements made of low dispersion ED glass and two aspherical lens elements to minimize coma and chromatic aberrations. The Nano Coating System (NCS) lowers reflections to provide increased contrast. Its internal focus system enables its compact design and keeps the front element from extending during focus. As a manual focus, manual aperture lens, it offers a wide, easy to grip focus ring and bright aperture, distance and depth of field markings. A removable petal-shaped lens hood and a carrying pouch are included.