FEATURES & SPECIFICATIONS:

Digitally Integrated Lenses for Top Imaging Performance Di (Digitally Integrated Design) is a Tamron designation that applies to lenses that have been optimized for digital capture using advanced multi-coating techniques and optical designs that assure excellent image quality across the entire picture field. Because of these characteristics, Di lenses provide outstanding performance on cameras with full-frame and APS-C format sensors as well as on 35mm film. Low Dispersion (LD) Glass for Greater Lens Sharpness Low 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 lowdispersion 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.) Macro Effect of 1:2 in Telephoto Zoom Range Flipping a macro switch in the focal length range of 180mm to 300mm allows entry into the macro range, for photography as close as 37.4" (95cm) from the subject. In the macro range, one can take advantage of the telephoto effect and a maximum magnification ratio up to 1:2. In addition, since the focal length in the macro range spans from 180mm to 300mm, zooming can also be used to adjust composition.