Canon has acknowledged that there is white spotting on an optical layer in front of the image sensor in some of their EOS 750D and 760D cameras.
Under certain shooting conditions, the white spots on the optical layer of image sensor may result in dark circular patterns on the captured image.
The phenomena does not affect all EOS 750D and 760D cameras. Those which might be affected have serial numbers starting with 01 or 02, as here:
01xxxxxxxxxx or 02xxxxxxxxxx
However, cameras that have a ● mark inside the battery cover shown in the figure below are not affected even if serial number as above.
Potentially affected cameras will be inspected and repaired free of charge, regardless of the warranty status. The inspection and repair service will begin on 20 May 2015.
If your product is one of those identified as potentially affected by this phenomenon, you should contact a Canon authorisd service facility: