The Irix 11mm f/4.0 Blackstone Lens for Pentax Dslr Cameras is a high-quality, professional-grade manual focus lens designed for photographers seeking superior image quality and sharpness. This innovative lens features an ultra-wide full-frame rectilinear design with an expansive angle of view of 126.5 degrees, making it an unbeatable tool for landscape, architecture, nightscape, and extreme photography.Constructed with four high refractive lenses, two Extra-low Dispersion (Ed) lenses, and three aspherical lenses, this lens ensures minimal distortion of just 3.13%, a unique feature in its class. The Irix 11mm lens is versatile and durable, boasting a solid aluminum alloy construction that is specially sealed for weather and dust resistance.The lens also incorporates a Focus Lock system and an Infinity Click feature, providing photographers with absolute control over their work. The rear filter slot accommodates 30x30mm gel filters, offering additional creative possibilities.