Obtain Image Dust Off reference data using an Image Dust Off-compatible camera.
(With the lens about 10 centimeters [four inches] from a well-lit, featureless white object, frame the object so it fills the viewfinder, then release the shutter.)
Shoot as usual. Dust on the low-pass filter will be photographed on the image.
Dust on the image has been reduced using the Image Dust Off feature of Capture NX.