For Vista camera.xml is located in:
C:\Users\your_user_name_here\AppData\Roaming\PlaneShift\options
AppData is a hidden folder. Two ways to find the file you want:
1) Turn on viewing of hidden folders by browsing to your user profile folder and pressing alt to pull up the menu, choose tools, and then folder options. Go to the view tab. The first radio button group on the list change selected to "Show hidden files and folders." Ok. You can now browse to the path.
2) Search feature. Open search but make sure you click the advanced search feature. This will give you extra options. Check the the checkbox for "Include non-indexed, hidden, and system files" Search for camera.xml.
Hope this helps.