A specialized, ultra-wide angle zoom, the HD PENTAX-D FA 15-30mm f/2.8 ED SDM WR Lens from Pentax offers full-frame shooters an excellent f/2.8 constant aperture to allow for exceptional control over depth of field and the ability to work in low-light conditions. It uses ED glass elements to reduce aberrations and features an HD multi-layer coating to limit flare and ghosting. Operation is fast, with a Supersonic Direct-Drive Motor (SDM) for autofocus and it has a Quick-Shift focus system for switching between auto and manual focusing. And, it can focus down to 11" for convenience.