This high zoom ratio lens is designed exclusively for digital SLR cameras & incorporates Sigmas original OS (Optical Stabiliser) technology This system offers the use of shutter speeds Approx. 4 stops slower SLD (Special Low Dispersion) & aspherical lenses provide excellent correction for all types of aberrations High image quality is assured throughout the entire zoom range Sigmas newly developed Thermally Stable Composite (TSC) allows for a more compact design & the HSM (Hyper Sonic Motor) ensures fast & quiet auto-focusing This lens has a minimum focusing distance of 35cm & a maximum magnification ratio of 129 making it convenient for close-up photography Sigmas unique OS technology This lens is equipped with Sigmas own unique OS technology This system offers the use of shutter speeds Approx. 4 stops slower It also compensates for camera shake when shooting moving subjects such as motor sports Sony & Pentax mounts do not incorporate Optical Stabilisation Superior image quality One SLD (Special Low Dispersion) glass element offers excellent correction of colour aberration & three aspherical lenses including a double-sided aspherical lens prevent & correct all types of aberrations such as astigmatism achieving high image quality throughout the entire zoom range Reduced Ghosting & Flare Sigmas Super Multi-Layer Coating reduces flare & ghosting ensuring sharp & high contrast images even in backlit conditions Minimum focusing distance of 35cm throughout the entire zoom range A minimum focusing distance of 35cm throughout the entire zoom range & a maximum magnification ratio of 129 makes this lens ideal for close-up photography When the APS-C size sensor is taken into consideration the effective maximum reproduction ratio becomes 12 Quiet & fast AF An inner focusing system & the incorporation of HSM provide fast & quiet auto-focusing AF will not function if the Pentax camera bodies do not support HSM Petal-type hood This lens is supplied with a Petal-type hood to block out extraneous light & reduce internal reflections Magnification scale A magnification scale is displayed on the lens barrel ensuring ease of use Vignetting will occur if the lens is used with digital cameras with image sensors larger than APS-C size or 35mm SLR cameras