Zeiss 85mm f/1.4 ZK Planar T* Manual Focus Lens for Pentax K-Mount Cameras Its shallow depth of field at wide apertures allows the use of selective focus to emphasize the primary subject by defocusing the background The 9-blade, circular aperture produces a smooth and natural rendition of defocused images, as well as nearly circular shapes of point sources of light Geometrical distortion is imperceptibly low, allowing high quality documentation photographs, both analog and digital