The Sigma 105mm f/2.8 EX DG HSM Macro Lens for Canon EOS Cameras delivers superb, distortion-free images throughout its broad focus range, from infinity telephoto to life-size (1:1) macro, as close as 12.2" (31 cm) without accessories. A Special Low Dispersion (SLD) lens and one high refractive index SLD lens provide excellent correction for all types of aberration and distortion. Its non-rotating front lens group makes it easier to work with polarizing filters. A focus limiter helps divide the broad focus range into more manageable chunks.