The Sigma fit Sigma 10-20mm F3.5 EX DC HSM is a super wide-angle lens with maximum aperture of F3.5 throughout the entire zoom range. It has two ELD glass elements & one SLD glass element which provide excellent correction of colour aberrations. Four aspherical lenses provide correction for distortion & allow its compact & lightweight construction. It also features a hyper sonic motor which enables quiet & high speed auto focus. The Sigma 10-20mm F3.5 EX DC HSM lens is designed for digital SLR cameras with an APS-C sized sensor & vignetting will occur if used with digital SLR cameras with larger sensors or 35mm film SLR cameras.