A versatile ultra-wide prime lens, the Pentax K-mount 11mm f/4 Firefly Lens from Irix balances a sophisticated optical design with a lightweight, durable physical construction. Aspherical, extra-low dispersion, and high-refractive index elements are used to suppress color fringing, chromatic and spherical aberrations, as well as unwanted distortion, and also contribute to producing a high degree of sharpness and clarity. Additionally, a Neutrino coating has been applied to limit lens flare and ghosting for improved contrast and color accuracy when working in strong lighting conditions.
In addition to the imaging performance, this 11mm f/4 utilizes 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 Firefly version of this focal length, this lens is also distinguished by a lightweight ABS plastic exterior, printed lens markings, and weather-sealing about the lens housing to permit working in trying environmental conditions.