CCD cleaning
Firstly, the filter that protects the CCD is removed. The position of the CCD can then be measured and, if necessary, adjusted.
A focus calibration is followed by very careful cleaning of the CCD with compressed air, cleaning fluid and tissues.
The unit is then mounted on a test stand set-up. A test shot is made, with the lens focus setting at infinity, through an illuminated piece of opal glass mounted in the filter thread of the lens. The unprocessed RAW-file is inspected on a monitor to ensure that that there is no residue of grease, fluid or dust on the sensor.
A mounting seal is attached and another test shot is made and inspected. The filter is then unwrapped, cleaned on both surfaces and mounted. The back is finally tested once more.
If, however, the back fails any of the inspections, the process is repeated.
After passing all tests, the unit is ready to be returned.