The Black HD Pentax DA 15mm f/4 ED AL Limited Lens from Pentax is a compact prime wide-angle lens providing a 35mm-equivalent focal length of 23mm. The lens' optical design includes features extra-low dispersion glass and one hybrid aspherical elements to minimize chromatic aberrations and limit distortion in order to enable a natural-looking expansive angle of view that is well-suited to both indoor and outdoor scenes. A high-grade multi-layer HD coating has been applied to lens elements to help minimize flare and ghosting for enhanced contrast, clarity, and color fidelity and a rounded seven-blade diaphragm contributes to an aesthetic out-of-focus quality to benefit shallow depth of field imagery. Additionally, an SP Protect coating has also been applied to the front lens element to effectively protect it from dirt, oil, and finger prints.
The compact form-factor of this lens integrates Pentax's Quick-Shift Focus System, which allows manual focus control over the lens at any time, even in AF mode, for precise handling over the focal plane.