Distinguished by its refined physical construction, the 11mm f/4 Blackstone Lens from Irix is an ultra-wide prime designed for Pentax K-mount DSLRs. As a rectilinear lens, the advanced optical layout makes use of aspherical, extra-low dispersion, and high-refractive index elements to control distortion and aberrations for accurate, and sharp rendering with a high degree of clarity and color accuracy. Additionally, a Neutrino coating has also been applied to the lens to control flare and ghosting for improved contrast when working in strong lighting conditions.
Beyond its optical assets, this 11mm f/4 lens also sports a manual focus design for fine-tuned control, and incorporates a unique positive focus lock to secure the focusing position at any point for consistent, repeatable shooting. As the Blackstone version of this focal length, this lens is also distinguished by an aluminum and magnesium alloy exterior, engraved lens markings with fluorescent UV paint for high visibility, and extensive weather-sealing about the lens to permit working in harsh environments.