Defocus Control - DC" stands for Defocus Control. DC allows the photographer to change the distortion characteristics of the lens so the "look" of the out-of-focus elements in the foreground or background can be changed to produce more pleasing photos, particularly portraits. For example, when shooting a nighttime portrait of someone with the lights of an amusement park in the background, the lights normally appear as round colored disks. Using the DC feature, the photographer can change the shape of the disks. Similarly, when shooting a daylight portrait against a leafy background, the shape of the out-of-focus highlights on the leaves can be changed.
basicamente vc pode controlar o tipo de desfoco (blur) vc quer na area fora do foco... eh como se vc escolhesse o quanto/tipo de bokeh vc quer...
ha uma versao 105mm q para DX vai te dar ~150mm...