I originally had LR4 and renamed some images. I've upgraded to LR5. I removed the images from the original LR4 catalog and have created a new catalog in LR5. I want to base my new file names on the original camera generated file names... But when I import the images into LR5 and look I the Metadata ( with "Exif and IPTC selected) it does NOT show the original camera generated file name... Only the name I assigned it in LR4. ) Is there any way to find/recover that? I can't believe with all the metadata saved lightroom would simply toss it???
original file name is only stored in the lightroom catalog file. This means, the original filename is stored in your LR4 catalog! After you upgraded to LR5 you simply have to open the LR4 catalog and LR5 will convert the catalog into an LR5 catalog.
I hope, you still have an LR4 catalog backup (before you removed all images)? Otherwise original file name is lost.