When I bought my Canon 30D in '06 I started putting ID info in the comments field using ZoomBrowserEX that Canon supplies. As my picture volume increased I found 2 problems with my workflow: 1) putting the same or similar ID into a large number of images was a real pain, and 2) If I needed to edit my comment ZoomBrowserEX tended to put the edits into a XMP sidecar file for the directory rather than individual files so moving an image left the ID behind in the old directory. To more automate workflow I started using exifutils from www.hugsan.com to insert the comments into the EXIF:UserComment field using a batch file. About the same time I started using Lightroom (I believe version II) which picked up the EXIF:UserComment field and placed it in the Caption as shown in this screenshot:
I was using exifutils rather than EXIFtools which does not directly support writing multiline comments. Starting with LR3, comments inserted with ZoomBrowserEX failed to import, but those inserted with exifutils would import. As near as we could figure the end of line codes used by ZoomBrowserEX caused LR problems while the CRLF inserted with exifutils was OK. Due to several problems with exifutils I was finally able to devise a workaround for inserting multiline comments using EXIFtools with the command line: perl C:\EXIFTOOL\exiftool.pl "-UserComment<=Cmt" 1401C_0989.cr2 after creating a multiline ID file named cmt. Using EXIFtools I have been working to extract the comments inserted with ZoomBrowserEX and reinsert them using EXIFtools which is time consuming for thousands of images. LR3 and LR4 have consistently imported these comments to the Caption field as shown above. Somewhere in the last updates to LR4 or the new LR5 these comments are no longer imported. I have verified by having LR export the metadata to an XMP file, as it does automatically with RAW images, that the EXIF:UserComments I inserted is in the XMP export for both images where the comment formerly imported to the Caption and those where it does not import now. The only difference in the image structure is what formerly imported no longer does.
I think but can't guarantee I have the above chronology exactly correct. After dealing with thousands of my dad's unidentified pictures I am trying to make mine have the location and subject data physically in the image and not in some sidecar file that can get lost. I need multiline comments that are visible in Canon's ZoomBrowserEX and Digital Photo Professional as well as Lightroom. If necessary I can insert the comment in multiple places within the image, but I really need to know where in the mysterious depths of Canon's RAW files LR can pickup a comment and place it in a visible field. The Caption is sort of convenient but another may do just as well. I also need to deal with RAW files from Canon's 30D, 70D and S95 as well as whatever camera I buy in the future.
Thank you very much for your help. I am running 64bit Win7 on an I3 processor. I think I started with one of the middle versions of LR2 and have done each update as they were issued and bought the upgrades couple of months after they come out. I enjoy using Lightroom despite some of its limitations, but needing to constantly reference another program to setup my keywords is a real pain.
John