Pentax 16-45mm f/4.0 SMC PDA  ED AL Zoom Lens for Pentax and Samsung Digital SLR Cameras Designed for proprietary PENTAX Kaf Mount Extra-low Dispersion (ED) glass lens for superior sharpness and color correction Responsive Quick-Shift Focus System allows instant shift from AF to MF Image circle is designed to match the CCD used in PENTAX digital SLRs Convert focal length to 24.5mm-69mm with *ist D (optional)