Vignetting, or light fall-off towards the edges of an image, is caused by a number of things. One is that rear lens elements are shaded by elements in front of them. Another is that sensor wells are better at picking up light when the light beam is perpendicular to the sensor, which is more the case in the middle than at the edge.

This is also why some sensors have micro lenses. Whatever causes the vignetting the DAC III removes the effect and gives you the ability to shoot even wide angle images with evenly distributed light from the center to the edge. It can be especially useful if you want to stitch images.

© Photo: Anders Espersen