The HD PENTAX-D FA 15-30mm f/2.8 ED SDM WR is a specialized, ultra-wide angle zoom lens designed for Pentax full-frame shooters. It offers a constant f/2.8 aperture throughout its zoom range, providing exceptional control over depth of field and allowing for impressive low-light performance.  

Key Features:

Ultra-wide Zoom Range: Covers a focal length range of 15-30mm, providing expansive views and unique perspectives.  
Constant Aperture: f/2.8 maximum aperture across the entire zoom range for consistent exposure and low-light capabilities.  
High-Quality Optics: Incorporates ED (Extra-low Dispersion) glass elements to minimize chromatic aberration and deliver sharp, high-contrast images.  
HD Coating: Reduces flare and ghosting for enhanced image clarity.  
Fast and Quiet Autofocus: Powered by a Supersonic Direct-Drive Motor (SDM) for quick and silent focusing.  
Weather-Sealed Construction: Resists dust and moisture for reliable performance in challenging conditions.  
Close Focusing: Minimum focusing distance of 11 inches for capturing detailed close-ups.
Quick-Shift Focus System: Allows for seamless switching between autofocus and manual focus.