Sigma has introduced an HSM version of its optically stabilized f/3.5-6.3 18mm-200mm autofocus zoom lens, which we tested recently. The addition of a built-in hypersonic motor (HSM) allows quiet, high-speed focusing and makes the lens fully compatible with all Nikon digital SLRs, including those that do not use body-driven autofocus motors, including the D40 and D40x. The lens is designed to be used with cameras that use APS-C-size sensors. Sigma warns that using the lens with larger sensors and film-based 35mm cameras will cause vignetting.

The lens offers a minimum focus distance of 17.7 inches throughout its focal-length range and a maximum magnification of 1:3.9. A magnification scale is displayed on the lens barrel, which also incorporates a zoom lock switch. The optics include a Special Low Dispersion element and three aspherical elements, as well as multi-layer coatings, to minimize optical flaws. The lens has a 72mm filter diameter.

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