In the View Pane menu, the first item is "View". Scroll down to Camera Settings, and switch from No Gate to Resolution Gate. Now you should have a strong reference for camera positioning.How do I check if the resolution gate is activated for the camera? I am not even sure of what that is...
What happened, I guess, is that if this is not activated maya uses the lateral borders of the view pane as image limit, that's why it seems not to match into one of the two dimension. Tho at a certain point I think the camera gate was set as default ?
Hope that helped, still you can point me to the version (or archive) of MtI you are using.