The Sigma18-50mm f/2.8-4.5 DC OS HSM is a lens dedicated to digital SLR cameras with APS-C size image sensors offering a large aperture and Sigma's Optical Stabilization and provides a high level of optical performance. The combination of the large aperture of f/2.8 and anti-shake function makes capturing exceptional photos in low light achievable, and the wide angle is well suited for indoor photography. It offers superior peripheral brightness as well as a compact and lightweight construction. Two SLD (Special Low Dispersion) glass elements and three Aspherical lenses provide excellent correction for all types of aberrations. The Super Multi-Layer Coating reduces flare and ghosting. Designed with inner focusing and inner zooming systems, high image quality is assured throughout the entire zoom range. This lens has a minimum focusing distance of 11.8 inches (30cm) throughout the entire zoom range and a maximum magnification ratio of 1:4.1.
Optical Image Stabilization Sigma's anti-shake function makes capturing exceptional photos in under most lighting situations achievable.
HSM Autofocusing for Canon D-SLR Cameras
Inner Focus System An inner focusing system eliminates front lens rotation, making the lens particularly suitable for using the petal-type lens hood (supplied) plus circular polarizing filters.
Excellent optical design Special Low Dispersion (SLD) and Extraordinary Low Dispersion (ELD) glass elements provide excellent correction of color aberrations. This lens produces an exceptional level of optical performance.
Reduced Ghosting and Flare The super multi-layer lens coating reduces flare and ghost. High image quality is assured throughout the entire zoom range.
Ideal For Portraits and Snaps With a minimum focusing distance of 7.9", and a maximum magnification of 1:3, this large aperture standard zoom lens, with close-up ability, is ideal for portrait and snap shots.
Compact and Lightweight Lens Its design incorporates both glass-mold and hybrid aspherical lens technology which offers a compact and lightweight construction.
This is the magnifying factor of a lens. Macro lenses will often be described by their “magnification factor”. A lens with a 1:1 magnification factor produces a projected image on the sensor which is the same as the subject.
The individual pieces of glass that form the overall optical construction. Most lenses have between four and eleven elements to bend the light rays to ensure a perfectly formed image appears on the light sensitive surface, such as a film or CCD. The elements are arranged in groups and may be seen in specification sheets as, for example, 6 elements in 4 groups. That configuration may have two single elements and the other four grouped in pairs.
A lens with a 1:1 magnification factor produces a projected image on the sensor which is the same as the subject. A 1:1 magnification factor is usually considered the minimum for a lens to be described as a “macro” lens. Specialist macro lenses are often 1:3 or even 1:10 magnification factors, meaning that 1mm across the subject becomes 3mm or 10mm when projected onto the sensor, thus 3 or 10 times magnification.