The Sigma 17-50mm f/2.8 EX DC OS HSM FLD large aperture standard zoom lens is for Canon digital DSLR cameras. This package includes a Sigma 17-50mm f/2.8 lens, Sandisk Ultra 32GB Memory Card and Photo4Less Cleaning Cloth.
The DC designation on the barrel means that this is a special lens designed so that the image circle matches the smaller size (APS-C) of the image sensor of your digital SLR. Its specialized design gives this lens the ideal properties for digital cameras, including a compact size and lightweight construction. The 17-50mm f/2.8 offers Sigma’s OS System (Optical Stabilization) that allows shooting at shutter speeds approximately 4 stops slower than would be otherwise possible, for sharper handheld photography even in low-light situations.
The Sigma is constructed with 17 elements in 13 groups, it features FLD (“F” Low Dispersion) glass which is the highest level low dispersion glass available with extremely high light transmission. This glass has a performance equal to fluorite glass which has a low refractive index and low dispersion compared to current optical glass.