Don’t get me wrong. Lightroom is a great program overall.
It combines photo editing and photo management into a single tool. It does non-destructive editing with RAW and Jpeg files, which means that the original file will always remain intact no matter the changes done to the final image. All of your develop edits are stored in Lightroom’s built-in database (aka catalog), just like every other tool you used, such as flags, collections, etc. But there is one problem with this type of centralized data storage. Your Lightroom catalog, just like any other database, will eventually fail. Corruption does happen from time to time. Maybe your computer had a power outage when it was writing changes, or maybe you accidentally merged two catalogs and it didn’t exactly go well. No matter what the exact reason is, chances are that your Lightroom catalog is likely going to fail in the near (or far) future, and it has already happened to me twice. Poof, you lose all of your changes. All of your collections, all of your picks, and of course, all of your develop changes.
One way (and the best way) of making sure that your catalog doesn’t fail is by backing it up, exactly what Lightroom recommends. Always do the weekly backups, as they will be lifesavers the day your actual catalog fails. It’s a no-brainer.
But why not add another layer of security to the integrated backup? This is where XMP sidecar files come in handy. Before we’ll even talk about the benefits of using XMP sidecar files, go check and turn ON that option now. I have no idea why Adobe doesn’t check it by default in the first place, but it definitely should be turned on.
Go to Lightroom (on Mac) or Edit (on PC) > Catalog Settings > Automatically write changes to XMP, and check that option.
XMP sidecar files are basically small files that add extra information, or metadata, to a picture. The XMP metadata includes most of the pictures’s embedded EXIF information, but most notably Lightroom’s develop panel/Adobe Camera Raw’s adjustments.
So why turn on XMP sidecar files? Here’s a few reasons :
1) Backup redundancy
As I’ve explained above, having the develop changes written to XMP furthermore adds an extra layer of safety. Also, a lot of users like to store their Lightroom catalogs on their main drive and their pictures on a secondary drive to optimize performance while saving space. This especially applies to people with both an SSD and HDD. In this case, you will get both backups along with your pictures (the XMP files) stored in the secondary drive as well as full backups of your catalog stored on your main drive.
2) Cross-program compatibility
Using XMP for backup is a good reason, but an ever better reason to use it is because it can also make your life much more convenient. If your workflow is a mix of both Lightroom and Photoshop, then XMP files is the perfect solution. They will allow you to sync your Lightroom develop module changes into Adobe Camera Raw seamlessly, and changes made in either program will be written on the XMP file.
Note : All of the above *might* work with Photoshop Elements since Camera Raw (although an older version) comes included with the program, but I haven’t tried it myself and there isn’t much information on that topic. If you can confirm whether it works or not, please tell me so and I’ll edit my article accordingly. 😀
3) Working with multiple catalogs
Many people, including me, like to work with multiple Lightroom catalogs for easier photo management. But the problem is that Lightroom was never really designed to do that. You can only open and edit one catalog at a time, and managing multiple catalogs constantly can be a pain. However, by using XMP sidecar files, you can sync each photo’s develop settings easily between catalogs. This is similar to the Photoshop sync above, and it does make your life much more easier if you tend to work with a same picture in different catalogs.
The bottom line
XMP sidecar files, as a general rule, makes your life much easier by incorporating all the information needed to process a RAW picture in a small file. The advantages of using XMP are obvious : not only do you have an additional layer of backup, but XMP also allows you to sync picture data between Adobe programs and within Lightroom itself.
That being said, is there any reason not to write changes to XMP? None as I know of. However, do keep in mind that unlike every other RAW format, XMP information is embedded in DNG files, which may or may not be impractical for you if you like to convert your proprietary RAW format to DNG.
XMP. Use it. Don’t learn that lesson the hard way when your catalog and backups fail.