This is a quick reminder for myself because even though I was able to find quite some information online, nothing really fit.

The situation was that a session was shot with two cameras. Unfortunately the clocks were off by about 25 minutes between the cameras. To make matters more complicated the files of both cameras were in the same directory sharing the same naming scheme. Because of this it was not as easy as applying exiftool to a certain directory or file naming scheme.

After having identified the time difference and which camera was off the task was to apply the time shift to only this camera's files.

$ exiftool -if '$model eq "Canon EOS 6D"' "-alldates-=0:0:0 0:25:0" .

The date format according to the exiftool documenation is Y:M:D h:m:s with a -= or += to shift back or forward in time.