Is there a way to tell whether a DNG is the result of converting a cr2/nef vs. jpeg or tiff? I seem to remember an "original file" field in the metadata in the past.
there is a tag "OriginalRawFileName" and afaik the canon marker "RecordMode" is preserved in the DNG file.
nikon and others should have such a tag too.
but LR will not show these tags by default.
you have to change the metadata view to DNG.
if you use exifgui you can view the RecordMode tag too.
Post deleted - sorry I misunderstood.