The Pentax DA 21mm f/3.2 Limited Lens is an extremely thin, compact and light-weight wide angle lens, designed exclusively for Pentax digital SLR cameras. This lens measures only 1" (25mm) long, and weighs a mere 4.9 ounces (140 grams).
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 image circle in DA-series lenses is designed to perfectly match the 23.5mm x 15.7mm size of the CCD used in Pentax digital SLR cameras to optimize camera performance. This design also contributes to a drastic reduction in size, weight and production cost, compared to 35mm-format counterparts with similar specifications.
This lens has a unique bayonet lenshood featuring a 43mm filter thread upon the inside of the hood itself. It isn't possible to use 49mm filters on the lens barrel with the special hood in place, and this hood in particular is a brilliantly-effective stray light eliminator, so if you wish to use a filter and the lens hood simultaneously it must be a 43mm filter.
Note! Not suitable for 35mm film SLR cameras