Canon USA has issued a service notice regarding a phenomenon where traces of the immediately preceding frame may be visible in an image file from the Canon 7D.  This has apparently occurred in situations using continuous shooting mode.  According to Canon, the problem “is not noticeable in an image with optimal exposure.”

As the notice states, “Canon is currently investigating and analyzing the cause of this phenomenon, and we are planning to release a firmware update to address this issue.”

I have been unable to reproduce this effect in testing the 7D today; however, an unofficial discussion and sample images demonstrating the problem appear in DPR forums here.  According to one observer, optimal conditions for reproducing this error include the following:

1. Shoot with maximum continuous shooting rate.(8.05fps)
2. Shoot with fast shutter speed.(>1/500s ?)
3. Image’s back ground is flat and bright.(Blue sky,etc)
4. Target is a fast moving object.(Bird,Jet fighter,etc)
5. 2nd or later frame image has a ghost of previous frame image.

You can read the entire service notice on Canon’s website.