Not particularly of interest to me as I shoot on EOS1D bodies, the Sigma DC lenses are designed specifically for the 1.5x and 1.6x image crop sensors, so things like the Nikon DSLRS or Canon 350D and similar.
The Sigma 18-200 will be the 35mm equivalent of a 27-300mm zoom with Optical Stabilisation.
Sigma Press Release says:
This high zoom ratio lens is exclusively designed for digital SLR cameras and is capable of covering a wide range of focal lengths from wide angle to telephoto. It is equipped with Sigma’s own unique OS (Optical Stabiliser) function. This function uses two sensors inside the lens to detect vertical and horizontal movement of the camera and works by moving an optical image stabilizing lens group, to effectively compensate for camera shake. It automatically detects movement of the camera and compensates for camera shake when shooting moving subject such as motor sports.
Two SLD (Special Low Dispersion) glass elements and three aspherical lenses provide excellent correction for all types of aberrations. The super multi-layer lens coating reduces flare and ghosting. This lens provides superior image quality throughout the entire zoom range.
An inner focusing system eliminates front lens rotation, making the lens particularly suitable for using circular polarising filters and the petal-type lens hood supplied.
Focal Length :18-200mm
Minimum Aperture :F22
Lens Construction :18 Elements in 13 Groups
Angle of View :69.3°-7.1°
Number of Diaphragm Blades :7pcs
Minimum Focusing Distance :45cm
Maximum Magnification :1:3.9
Filter Size :72mm
Lens Hood :Fixed Petal-type
Dimensions :Diameter 79mm (3.1”) x Length 100mm (3.9”)
Weight :610gr/21.7 oz
Available for Sigma AF