Covering a versatile range of wide-angle focal lengths, the HD Pentax DA* 11-18mm f/2.8 ED DC AW from Pentax is a 17-27.5mm-equivalent zoom for APS-C-format cameras. The lens's wide design and bright f/2.8 maximum aperture make it particularly well-suited to astrophotography applications, as well as landscape and interior shooting. The optical design incorporates a series of aspherical and low dispersion elements, which help to control distortion and color fringing for improved sharpness and clarity, and an Aero Bright II Coating has been applied to benefit contrast and color accuracy. Additionally, a Super Protect Coating, along with a weather-sealed design, make this lens suitable for use in trying weather conditions.
- Wide-angle zoom is designed for APS-C-format Pentax K-mount cameras and offers a 17-27.5mm equivalent focal length range.
- Constant f/2.8 maximum aperture suits working in difficult lighting conditions and offers consistent illumination throughout the zoom range.
- Two aspherical elements, two extra-low dispersion elements, and one aspherical element made from extra-low dispersion glass are used to significantly reduce both spherical and chromatic aberrations throughout the zoom range for improved sharpness, clarity, and color accuracy.
- Aero Bright II Coating has been applied to individual elements to minimize ghosting and flare for greater contrast and color neutrality when working in strong lighting conditions.
- SP (Super Protect) Coating has also been applied to the front element to guard against moisture and grease.
- DC motor delivers quick and precise autofocus performance and an integrated Focus Clamp mechanism can be used to lock the focusing position in place to prevent accidental adjustments. A quick-shift focusing clutch mechanism also affords fast switching between autofocus and manual focus operation.
- Weather-resistant construction incorporates 10 distinct seals about the lens body to prevent the intrusion of moisture or dust.
- Dedicated space for wrapping an optional heating device around the lens to prevent freezing and condensation from accumulating when working in cold temperatures.
- Rounded nine-blade diaphragm contributes to a pleasing bokeh quality.
