Canon EOS 5D Mark III Instruction Manual (en)

 Appending Dust Delete DataN
Photograph a solid-white object.
At a distance of 20 cm - 30 cm (0.7 ft. 
- 1.0 ft.), fill the viewfinder with a 
patternless, solid-white object and 
take a picture.
The picture will be taken in aperture-
priority AE mode at an aperture of  f/22.
Since the image will not be saved, the 
data can still be obtained even if there 
is no card in the camera.
When the picture is taken, the camera will 
start collecting the Dust Delete Data. 
When the Dust Delete Data is obtained, a 
message will appear. Select [OK], and 
the menu will reappear.
If the data was not obtained 
successfully, a message to that effect 
will appear. Follow the “Preparation” 
procedure on the preceding page, then 
select [OK]. Take the picture again.
After the Dust Delete Data is obtained, it is appended to all the JPEG 
and RAW images captured thereafter. Before an important shoot, you 
should update the Dust Delete Data by obtaining it again.
For details about using Digital Photo Professional (provided software, 
p.394) to erase dust spots, refer to the Digital Photo Professional 
Instruction Manual (p.396).
The Dust Delete Data appended to the image is so small that it hardly 
affects the image file size.
About the Dust Delete Data
Be sure to use a solid-white object such as a new sheet of white paper. If the 
paper has any pattern or design, it may be recognized as dust data and 
affect the accuracy of the dust deletion with the software.