No chance for dust and dirt

To achieve optimum image quality the sensor needs to be kept free of dust. As pixels today are the same size as dust particles or even much smaller, a single speck of dust on the image sensor can drastically reduce the quality of the image.

The short distance to the pixel means that under certain lighting conditions a speck of dust on the image sensor can cast the pixel beneath it entirely in shadow. The speck of dust appears as a dark spot in the camera image.