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.

• The Firefly version of the 11mm f/4 lens features a lightweight ABS plastic exterior construction that is sealed against moisture and dust along the main body of the lens. The Firefly construction also incorporates a rubber focus ring for improved grip and control, and has printed focus distance and depth of field scales to aid working with pre-focusing and hyperfocal focusing techniques.
• Ultra wide-angle prime designed for full-frame Pentax K-mount DSLRs, this lens can also be used on APS-C models where it provides a 16.5mm equivalent focal length.
• Three aspherical, four high-refractive index, and two extra-low dispersion elements are featured within the optical design to limit both spherical and chromatic aberrations, as well as color fringing and distortion, for improved clarity, sharpness, and even illumination.
• A Neutrino coating has been applied to limit lens flare and ghosting for improved contrast and color fidelity.
• Manual focus designed is benefitted by a positive focus lock mechanism to secure your focus position at any point to limit unwanted shifting of focus.
• A hard click stop indicates the infinity position on the focus ring for easy use in low-visibility conditions.
• Large depth of field scale benefits using hyperfocal and pre-focus techniques.
• Built-in petal-shaped lens hood blocks stray light in order to reduce lens flare, and also protects the front element of the lens.
• Rear of the lens accepts 30 x 30mm cut gel filters.
• Rounded nine-blade diaphragm contributes to smooth bokeh.
• Includes complimentary additional rear lens cap.