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. It 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. In addition to the state-of-the-art HD coating and a 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.
With its two-times zoom coverage from 20mm to 40mm, this lens offers 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.
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 minimising astigmatism over the entire zoom range. It allows the photographer to optimise 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 high-grade aluminium 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.
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.
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.