The inside of a digital camera is a veritable dust magnet. Every time you swap lenses you’re effectively inviting particles of dust to swirl right in and stick, courtesy of the electrostatic charge the interior of the camera carries, to the mirror, body chamber, and the camera’s sensor. While it’s less than ideal to have dust anywhere inside the body of the camera, the only time it becomes a real nuisance is when it clings to the sensor and appears in your photos.
Once the dust is on the sensor it rarely moves; the only way to banish the gray dots and black spots from your future pictures is to clean the sensor. Most people are completely freaked out by the idea of undertaking such a task, believing that the sensor is far too delicate for mere mortals to touch. We assure you that cleaning your camera’s sensor is not only easy and almost entirely risk free (when done patiently and with the proper tools, of course), but that it’s downright economical.