A high performance 11.1x zoom lens for Nikon digital SLR cameras with APS-C sensors
Optical stabilisation to compensate for camera shake
Hypersonic Motor (HSM) for quiet, high speed photography
One SLD and three aspherical elements for excellent correction of all types of abberations.
Multi-layer coating optimises quality for digital photography.
27-300mm equivalent focal length range; F3.5-6.3 maximum aperture.
Available for Canon, Nikon and Sigma mounts (APS-C/DX format DSLRs only)
The Sigma 18-200mm f/3.5-6.3 DC OS HSM is the latest in the company's long line of superzooms, which stretches back to the early 1990s and a series of 28-200mm (and later 28-300mm) lenses for 35mm SLRs. In fact Sigma was the first company to produce a superzoom for the burgeoning budget DSLR market, with its 18-125mm D3.5-5.6 DC of August 2004, followed shortly after by an 18-200mm F3.5-6.3 DC in February 2005. However the big problem with long, slow zooms is image blur due to camera shake, and in March 2007 Sigma duly announced this new version of the 18-200mm with the addition of 'Optical Stabilization' (OS) technology for Canon, Nikon and its own SD range of DSLRs (Sony and Pentax users, of course, benefit from sensor-shift image stabilization of all lenses). In somewhat curious fashion, the Nikon mount version also sports an ultrasonic-type 'HyperSonic Motor' (giving rise to the HSM tag,) while the Canon and Sigma mount models use a conventional micro-motor for focusing.
Like all superzooms the Sigma 18-200mm OS features a complex optical design, in this case 18 elements in 13 groups including one Super-Low Dispersion (SLD) glass element, and no fewer than three aspherical elements to combat aberrations. A minimum focus distance of 0.45m through the entire range adds to the lens's all-round versatility. The optical stabilization system detects when the camera is panning and automatically switches to operating in one axis only, useful for shooting moving subjects such as sports.