Is there someway to get the actual modified date of a file in a document library. Modified field has the modified date for the item and not the file so if one of the meta data of the file changes the modified field changes. Is it possible to use Property Promotion or something when uploading the file to get this property into some column?
You can find out other document properties using this powershell (or convert to c#)
I think the only way you could achieve this by creating an event receiver in code.
So you could check every time a document is uploaded or modified check the time of the file and set it to a desired column
just an idea :)
you can find some info about event receivers here.