A dust reduction system, or dust removal system, is used in several makes of digital cameras to remove dust from the image sensor. Every time lenses are changed, dust may enter the camera body and settle on the image sensor. Digital single-lens reflex cameras (DSLR) are particularly vulnerable to this issue, since the interior of the camera is exposed during lens changes unlike other forms of digital cameras, and the image sensor is fixed, unlike a film camera.
https://en.wikipedia.org/wiki/Dust_reduction_system
A dust reduction system, or dust removal system, is used in several makes of digital cameras to remove dust from the image sensor. Every time lenses are changed, dust may enter the camera body and settle on the image sensor. Digital single-lens reflex cameras (DSLR) are particularly vulnerable to this issue, since the interior of the camera is exposed during lens changes unlike other forms of digital cameras, and the image sensor is fixed, unlike a film camera.
