The HD PENTAX-D FA 150-450mm F4.5-5.6 ED DC AW super-telephoto zoom lens is designed for use with PENTAX K-mount digital SLR cameras. It has been developed to cover focal lengths from 150mm to 450mm ? a focal-length range most demanded by high-end PENTAX-camera users. It features the PENTAX-original, high-grade HD Coating to produce extra-sharp, high-contrast images even under demanding lighting conditions such as in backlight. It also incorporates three ED (Extra-low Dispersion) glass elements and a super-low dispersion glass element to effectively compensate for chromatic aberration. Its dustproof, weather-resistant body also makes it extremely dependable and durable in demanding outdoor conditions. Image circle covering Full-frame sensor 3X ratio super telephoto zoom (eq to 230-690 for APS-C) Dependable weather-resistant construction against humidity and dust (21 protection joins) Smooth, quiet autofocus operation driven by a built-in DC motor HD Coating to optimise light transmittance and minimise reflection ED lens elements for brilliant sharpness and saturated colours Focus Range Limiter (Full, 2-6m, 6m-?) Round shaped diaphragm to produce beautiful bokeh Super Protect coating of the front lens element for effective protection Super-telephoto coverage with three-times zoom ratio When mounted on a PENTAX K-mount SLR camera body, this zoom lens covers a super-telephoto range from approximately 230mm to 690mm in the 35mm format. It is designed to be compact and light enough to handhold during long-range shooting of such subjects as wildlife, aircraft and sports. Outstanding image definition Thanks to its state-of-the-art optics featuring three ED (Extra-low Dispersion) glass elements and one super low dispersion glass element, this zoom lens effectively minimises spherical and chromatic aberrations, while producing crisp, high-quality images free of colour bleeding. Its MTF (Modulation Transfer Function) curve is programmed to be higher than those of conventional models in the same class to deliver high-resolution, fine detailed images. Its image circle is optimised to cover even the image size of 35mm film-format SLR cameras. As the result, it not only assures brilliant, high-resolution images without compromising the sharpness at edges even when mounted on an existing PENTAX digital SLR camera body, but it is also capable of accepting future models with larger image sensors without modifications. HD Coating to optimise image rendition This lens is treated with the high-grade, multi-layer HD Coating.* Compared with?conventional multi-layer coatings, this PENTAX-original coating assures higher light transmittance and less reflection to deliver bright, high contrast images free of flare and ghost images, even under demanding lighting conditions such as backlight. HD stands for High Definition.