The DNG file format by its very nature and design does not utilize the XMP sidecar file. I don't work for Adobe, and I don't have any inside information. But I suspect that adding an XMP option is probably not in the plans. Personally, I work on the original raw files from my cameras. I don't create XMP files for them. I create a backup of the original files. Then, from then on, I rely on the catalog backups. The catalog contains all of the adjustments I have made to the original files. So I have been confident in relying on the catalog backups and the archived original NEF files. So far, I haven't regretted that workflow.
It would be wonderful to convert my images to DNG
What happens if you instruct Lightroom to NOT write XMP to the DNG files (which, by the way, is the default mode of operation for Lightroom). Does that meet your needs (which I don't see clearly explained)? It certainly reduces backup time. And since you are transferring the catalog file anyway, you don't need XMP.
I would prefer converting my native raw files to DNG for the future (various native formats from different manufacturers, you know the situation).
By the way, there are lots of people who don't believe this is a valid reason for converting to DNG. Adobe and similar software manufacturers are not going to eliminate support for RAW photos ... if they did, they would immediately lose sales, all those people who have RAW photos will no longer want to use Adobe software.
Thanks for your reply Jim. Within Lightroom, I guess the changes are kept in the catalog, and we could 'se' them in the development module. But we need to stay within Adobe Lightroom, i.e. it 'locks you in'!. Not that it's a bad thing, Adobe has done a marvelous job, but if anyone wans to take the images in another software, there would not be compatibility - which is possible with a xmp file. And then, there adjustments made out of LR (Photoshop, Nik or other) that need to be imported in TIFF anyway.. so maybe I jusd need to trust the "one" system of Adobe CC... it feels like the same control that Apple has on it's products, and I like to have flexibility..
thanks also dj. Wether one instructs Lightroom to write or NOT write XMP to the DNG files, the DNG file changes every time you modify it. So the backup is the size of the DNG file rather than the size of the xmp file. So, that does not solve my issue..
As for DNG versus native RAW, I have also been doing my workflow using native raw format (canon, panasonic and nikon) with the assumption that neither of the large camera manufacturers would want us to "lose" our images, so I would hope they maintain an openned to their proprietary format so that any software developer (Adobe or other) can read their native files... but why would Adobe have made the open DNG format?
Whether one instructs Lightroom to write or NOT write XMP to the DNG files, the DNG file changes every time you modify it.
Hmm, that doesn't happen to me if I uncheck the option Catalog Settings > Metadata > Automatically Write Changes Into XMP. When I edit a DNG in the Develop module or change its metadata in the Library module, the metadata status indicator indicates that the metadata inside the catalog has changed but hasn't been written back to the file:
But the operating system's last-modified date as shown in the Finder or File Explorer hasn't changed.
Are you sure that the the last-modified date is changing for you?
While you refer to taking images to other apps, embedded xmp metadata has always been more compatible with other apps than are sidecars, and Lr does write metadata to the DNG's embedded xmp metadata. If Adobe suddenly added sidecars for DNGs (and why not other non proprietary formats?) then other apps would need to be altered to handle conflicts where metadata could be in more than one place. And yet you accuse Adobe of locking you in?
Remember that the xmp sidecar does not contain all your Lightroom work. It omits stacks, flags, history steps, assignment to collections, virtual copies.... That's partly because the xmp is intended for data interchange with other apps, which don't understand such stuff, not primarily for backup. If you do use it for backup, remember it's only a second rate backup of your Lr work. For 100% coverage of your photos and work, backup the DNGs a single time when they are created, and routinely backup the catalogue.
As for comparing Lr to Apple's standards, did Apple ever save adjustment data to sidecars? Did Apple ever save any metadata to a catalogued file as an xmp sidecar? And yet you accuse Adobe of being Apple-like?
Sidecars are a hack for proprietary raw files. The lack of sidecars is an advantage of formats like DNG, TIF, PSD, JPEG.
The DNG file does not get changed by Lightroom. All files in Lightroom remain in their original state. So the files should only have to be backed up once. Then the catalog, which DOES contain all of your Lightroom adjustments, is the file that needs to be backed up routinely. What is it that gives you the impression that the DNG file changes?
Thanks John, I did not try it before - so I cannot say it changes the file for me.. it was apparently a wrong assumption. John Beardworth's reply confirms that. Thanks
Thank you for these clarifications John (Beardworth). Your reply as well as John's reply confirm that the LRCAT and no sidecar are the most complete methods. I do with to say that I was in no means trying to be insulting or accusing of Adobe. I totally respect Adobe, and use and pay for their wonderful products.
Your explanation notes clarify even more and provide additional information about sidecar files that were completely unknown to me, so thanks.
I think I got it now! Thanks to all respondents, these forums are a wonderful source of information. p
I must have had Lightroom add xmp information to DNG because mine changed. I will change my workflow and make sure I get the software to exclude sidecar files, thus keeping the dng intact.
Thanks again for all your help.. it's wonderful
Do remember that even if you write metadata to the DNG, that doesn't mean you must back up that DNG file. You can if you want, but you get 100% backup coverage of your images and the work done on them if your backup strategy is to backup the DNGs when they are first created (I call these the "virgin" DNGs) and routinely backup the catalogue lrcat file. If there's a disaster, restore the virgins and the catalogue and you've got everything. The "working" DNGs (ie the ones listed in the catalogue) don't need backing up after you write metadata to them - it eats up disc space and gives you a second rate backup which doesn't include all your work.
Sorry for being a bit sharp with "accuse"
this discussion has been good for me. I never realized the lrcat had more info than the xmp files. Luckily, I have always backed that up also. I will definitely change my workflow that way from now on.
As a side question, although this is a LR forum, why does Photoshop not save in DNG, and what is Photoshop Raw (because I can't even open the new *.raw file I created... I also created a TIFF and a PSD file, so I am ok, but I don't get it.. should I send this through the Photoshop forum instead?
A DNG file is a raw file. Photoshop is not capable of generating raw image data. Photoshop is not capable of doing anything with raw image data. By the time an image is opened in Photoshop it no longer contains raw image data. So the conversion process has to be done in Camera Raw because that plug-in is capable of working with the raw image data.