The optical stabilization helps to reduce camera shake induced blur and allows you to use slower shutter speeds than would otherwise be possible. The hypersonic focusing motor makes for quicker autofocusing.
The Sigma 50-200mm f/4-5.6 DC OS HSM will be available for Sigma, Canon, Nikon, Sony and Pentax DSLRs.
More details from Sigma’s press release below.
The Sigma Corporation is pleased to announce the new SIGMA 50-200mm F4-5.6 DC OS HSM. This compact high-performance telephoto zoom lens incorporates Sigma’s own Optical Stabilizer function. The lens incorporates SLD (Special Low Dispersion) glass in the front lens group and is equipped with an inner focusing system to provide high image quality throughout the entire zoom range.
The incorporation of HSM (Hyper Sonic Motor) ensures quiet and high-speed auto focus. The OS (Optical Stabilizer) function effectively eliminates the effects of camera shake so subjects can be easily and clearly seen in the viewfinder as well as in the image. It allows the use of shutter speeds approximately 4 stops slower than normal for steady, handheld photography.
For Sony and Pentax mounts he built-in OS System operates in conjunction with a camera body equipped with an anti-shake function and can be used as an alternative with cameras having built-in image stabilization. The Super Multi-Layer Coating reduces flare and ghosting and provides high contrast images throughout the entire zoom range.
This lens has a minimum focusing distance of 110cm (43.3 inches) throughout the entire zoom range and a maximum magnification ratio is 1:4.5. An inner focusing system eliminates front lens rotation, making it suitable for use with circular polarizing filters.
* Vignetting will occur if the lens is used with 35mm SLR cameras or digital cameras with image sensors larger than APS-C size.