The Pentax HD DA 20-40mm F2.8-4 ED Limited DC WR Lens  features a two-times zoom range covering focal lengths from moderate wide angle to standard, and a large maximum aperture of F2.8 at its wide-angle end.
This model is the first zoom lens of the high-grade Limited Lens series, which is renowned for its exceptional visual description, distinctive appearance and meticulous finish in every detail. In addition to the state-of-the-art HD coating and completely round-shaped diaphragm, it also comes equipped with a weather-resistant construction for the first time in the Limited Lens series, and a smooth, quiet AF system driven by a lens-installed AF motor, to capture beautiful, high-quality images, even under demanding weather and environmental conditions.
- Equivalent to 30.5-61.5mm in 35mm
- Dependable weather-resistant construction
- Lens-installed AF driving motor
- High Definition Coating
- Round shaped diaphragm
The first two-times zoom lens of the Limited Lens series
With its two-times zoom coverage from 20mm to 40mm, this lens offers a focal-length coverage from 30.5mm to 61.5mm (in the 35mm format) when mounted on a PENTAX K-series lens-interchangeable digital cameras body. It provides the most frequently used focal lengths required for many popular applications, such as scenic photography, snapshots and portraiture, making it the ideal choice as an all-purpose, everyday lens.
Acclaimed Limited Lens-series quality for superb visual description and premium appearance
Inheriting the design concept of the Limited Lens series, this lens is designed with an optical construction that faithfully reproduces the feeling of depth while minimizing astigmatism over the entire zoom range. It allows the photographer to optimize the subject's visual description, by making its appearance softer at larger apertures and sharper at smaller apertures. Its lens barrel, hood and cap are made of a high-grade aluminum material, and hand-machined for perfect proportions and beautiful texture. Positioned in the mid-section of the lens barrel, the zoom ring features a series of knurled grooves to facilitate zooming operation.
State-of-the-art optical technology
The lens has been treated with the PENTAX-developed HD coating*, a high-grade, multi-layer coating that reduces reflectance in the visible light spectrum to less than 50 percent of that of conventional multi-layer coatings. This allows the user to capture crisp, high-contrast images free of flare and ghost images, even under such adverse lighting conditions as backlight. It also incorporates an ED (Extra-low Dispersion) glass and a super-low-dispersion glass element in its optics to deliver clear, high-resolution images with edge-to-edge sharpness, while effectively compensating for chromatic aberrations over the entire zoom range.
* HD stands for High Resolution.
The first weather-resistant lens in the Limited Lens series
This lens is the first Limited Lens-series model to feature a weather-resistant construction, with seven special seals to prevent the intrusion of water and moisture into the lens interior. By mounting it on a PENTAX weather-resistant digital SLR camera body, the user is assured of greater durability and reliability when shooting in the rain or mist, as well as at locations subject to spray or splashes.