A truly wide-angle prime, the Ultra Wide-Heliar 12mm f/5.6 Aspherical III from Voigtlander features an updated Heliar design to render a rectilinear image, limit distortion, and maintain consistent sharpness and illumination to suit mirrorless camera designs. One aspherical element is employed in the 12 elements, 10 groups optical design to control spherical aberrations and distortions throughout the aperture range. The lens also uses a manual focus design to permit fine-tuned control over focus placement, with a minimum focusing distance of 11.8", and a Selective Aperture Control System allows you to de-click the manual aperture ring for smooth, silent exposure adjustment to suit filmmaking applications.