The black HD Pentax DA 21mm f/3.2 AL Limited Lens from Pentax is a compact pancake-style prime wide-angle lens providing a 35mm-equivalent focal length of 31.5mm. The broad 68° angle of view is well-suited to all-around shooting for both interior and exterior locations. 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 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.