Pentax SMC P-DA 16- 50mm Zoom Lens with Case, 21650
Designed for exclusive use with Pentax digital SLR cameras, the Pentax DA* 16-50mm f/2.8 wide-angle zoom lens is a terrific choice for landscapes, portraiture, and just about any other application. The lens features a tightly sealed, weather-resistant and dust-resistant construction to enhance durability in rainy or dusty conditions. The lens's three aspherical elements and two special optical glass elements, meanwhile, help compensate for chromatic and spherical aberration, producing images with superior contrast, clarity, and edge-to-edge sharpness. And thanks to the lens's Pentax-original Quick-Shift Focus System, you can easily and instantly switch from autofocus to manual focus.
Specifications

Focal length: 16-50mm
Maximum aperture: f/2.8
Minimum aperture: f/22
Lens construction: 15 elements in 12 groups
Angle of view: 83 to 31.5 degrees (when used with Pentax digital SLR camera body)
Number of diaphragm blades: 9
Metering system: TTL open-aperture metering
Minimum focusing distance: 0.3 meters
Maximum magnification: 0.21x
Filter size: 77mm
Corresponding AF mounts: Pentax KAF2
Dimensions: 3.3 inches in diameter and 3.9 inches long
Weight: 19.9 ounces (without hood)
Warranty: 1 year