The 18-200mm range is popular amongst those who own a camera with an APS-C sensor and wish to travel light, with the convenience of a large 11.1x zoom range.
The optically stabilised version of this lens, we are reviewing here, is available to fit Sigma, Nikon and Canon cameras. A non-stabilised version is also available for Pentax and Sony cameras. In addition to the optical stabilisation and huge zoom range, this lens sports a silent HSM focusing motor, although it doesn't support full time manual focus override.
Sigma 18-200mm f/3.5-6.3 II DC OS HSM Handling and features
Weighing only 495g, this optic is lighter and slightly more compact than equivalent lenses from Canon and Nikon. However, the maximum aperture drops to a fairly modest f/6.3 at 200mm, which may be limiting for shooting in low light, requiring slower shutter speeds and/or higher ISO sensitivities to be used to compensate. The lens balances well on the Nikon D300 used for testing, and should also feel right at home on more compact entry-level camera bodies too.
High quality plastics have been used for much of the lens' construction, with a matt finish that doesn't mark easily and the lens mount is made of metal. A wide rubberised zoom ring fills much of the lens barrel and the zoom action feels very smooth indeed, having just enough resistance to prevent the zoom creeping through the range when pointed downwards. A locking switch is provided to hold the lens at 18mm during transport.
A silent HSM focusing motor powers the focusing mechanism, resulting in reasonably quick focusing, although not as fast as some equivalent lenses. Moving subjects can be a challenge to accurately get in focus as a result. Focusing is performed internally, so the 62mm filter thread does not rotate, making this lens ideal for use with polarising and graduated filters