Sometimes you have problems that you can't find solutions to and you push it to the future how to solve it. In my data there are photos I took already in 2013 that I accidentally have the camera's auto rotation turned on. As a result, as the mount moved during the night, the orientation of some of the photos changed.
Since then I have tried to change the rotation so that all of the raw photos will be back to a horizontal orientation again which many of the astro software require. Changing the orientation is easy in most software, but to save them in Canon's .cr2 format again I never found a solution to until now.
Here's how I solved it:
http://www.astrofriend.eu/astronomy/...raw-files.html
I have only done this on Canon's .cr2 files. Let me know if you can use this for other cameras, Nikon, Sony etc. You have at least to change the file extension in the batch file.
/Lars