The Pentax Wide Angle 21mm f/3.2 AL Limited Series Autofocus Lens is a newly developed, high-performance optics, this new lens measures only one inch (25 millimeters long) and weighs a mere 4.9 ounces (140 grams). Mounted on a PENTAX digital SLR camera body, the lens protrudes very little from the camera's front panel, making it an ideal choice for carry-everywhere, instantaneous snapshot photography.
This versatile angle of view produces natural images with a moderate perspective and an expanded depth of field (or a wide in-focus area), making it ideal for many different types of subjects and occasions, including snapshots, landscape, travel photos, and architecture.
The DA 21mm incorporates a hybrid aspherical lens in its eighth optical element to effectively compensate for a variety of aberrations, which cause adverse effects on overall image quality. In order to assure high-quality image reproduction over the entire focusing range, it also features a floating mechanism, which is designed to adjust the degree of aberration compensation in relation to the focusing distance.