Tamron AF 70-300mm f/4.0-5.6 Di LD Macro Zoom Lens for Canon Digital SLR Cameras (Model A17E)
Designed for optimum handling ease and portability (it weighs only 458g <16.2oz.> ), it’s ideal for handheld shooting with full-frame and APS-C format SLRs. Its unsurpassed close-focusing ability (down to 0.95m (3.1 feet ) or 1:2 in macro mode) makes it perfect for nature and portrait photography.Zoom in to 300mm from a distanceAF 70-300mm f/4.0-5.6 Di LD Macro Zoom Lens FeaturesLow Dispersion (LD) Glass for Greater Lens SharpnessLow dispersion (LD) glass elements in a lens help reduce chromatic  aberration; the tendency of light of different colors to come to  different points of focus at the image plane. Chromatic aberration  reduces the sharpness of an image, but glass with an extremely low  dispersion index, has less of a tendency to separate (defract) a ray of  light into a rainbow of colors. This characteristic allows the lens  designer to effectively compensate for chromatic aberration at the  center of the field (on axis), a particular problem at long focal  lengths (the telephoto end of the zoom range), and for lateral chromatic  aberration (towards the edges of the field) that often occurs at short  focal lengths (the wide-angle end of the zoom range.)"