SLD (Special Low Dispersion) glass
Sigma use SLD (Special Low Dispersion) glass in this lens for excellent correction of chromatic aberration (colour fringing). This also corrects for fluctuation of aberration due to focusing. The new multi layer lens coating reduces flare and ghosting, a common problem with digital cameras and also creates an optimum colour balance.
Macro shooting with maximum magnification 1:2
The minimum focusing distance is 1.5 m/59 inches at all zoom settings between 200-300mm. It also has a switch for changeover to macro photography at focal lengths between 200mm and 300mm with a maximum close-up magnification from 1:2.9 to 1:2. This means that without changing the distance between camera and subject it is possible to change the shooting magnification.