The Enigma of Two Computers


Most professional photographers feel right at home with Lightroom. While it might be unrealistic to ever completely master any Adobe program, most of us feel fairly proficient with the intuitive nature of this program. Still, there are a few scenarios where our familiarity with Lightroom can quickly turn into a messy haze of confusion. Moving from one computer to the next is one of those workflow pieces that feels like it should be very simple but might be a frustrating mystery even to veterans.  

Editing Photos On Two Computers

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Why is it so complicated?


At the core of the issue is the way LR fundamentally works with files. See when you edit a photo on LR, you’re not actually editing the photo itself. All your photo editing is saved to the LR catalog itself and not onto the RAW file. Nothing you do in LR is actually being saved to the photos themselves. LR just remembers everything you did to the photo and superimposes your edits on the previews. So when you more your RAW files onto an external drive and take them over to another computer, the RAW files are in their original out-of-camera versions. Oh, if there were only some way to change that (foreshadowing). 

The Solution is Simple


The good news is that there is a very simple way to save your editing right onto the RAW files (well, kind of), but before I go on I should pause here because Lightroom does has a few solutions for working on multiple machines. There’s LR (not classic), exporting catalogs and even creating a cloud folder that updates on multiple machines. For this article, though, I’ve decided to go with the write-changes-to-XMP method because it’s the simplest to work with, even if it takes a little bit to understand its mechanics. 

Writing Changes to XMP Files


I’ll explain what XMP files are at the end of this article because I've decided to write the most practical information up front so that if you just need a quick solution you can get to it. But for now, we'll just saw that writing your changes to XMP is LR speak for saving your editing to the RAW files. If you run into problems using this method you might need to come back and finish the article to understand enough to trouble shoot the problem, but honestly the method is pretty simple. You just need an external solid state drive (SSD) and toggle one switch in your Lightroom preferences. The setting is called “Automatically write changes to XMP files. To do so, go to the edit menu in your tool bar and select “Catalog Settings” under the Metadata tab, you’ll find the check box.

By default "Automatically write changes into XMP" is unchecked for optimal LR performance

The Happyness Switch


By checking the box labeled “Automatically write changes to XMP files” in your preferences, any changes you make to your images in Lightroom will be saved to your files. This includes any presets applied, copywrite data, star ratings, and adjustment tools like healing, gradient, cropping. I am not aware of any adjustments that do not save to XMP files. The helpfulness of this feature can’t be overstated… well maybe this guy got too excited about this feature (https://vimeo.com/4672564). He calls it the happiness switch. 

So How Does This Help?


I’ll explain XMP files and what they are later on, but for those of you who want to stop at this paragraph and get to work, all you need to know is that once you’ve turn on “Automatically write changes to XMP files” all you have to do is save your RAW files to an external hard drive and import them on your second machine. When you import them to your second machine, it will automatically see everything you did to your image on your first machine and include those changes on import. If your second machine also has the feature turned on then you can make more adjustments which will be automatically saved. And voila! You can move files from one computer to the next while keeping your LR adjustments! If you only need to move the files in one direction, you’re all done! For those of you who are wondering, “what if I want to take the files back to the first computer after I’ve made changes on the second?” you’ll have to read on a little more. 

Going Back to the First Computer Takes An Extra Step


If you plan on going back and forth between two computers, there’s something you need to be aware of. Lightroom will not automatically update the changes you made to the second computer when you take the files back to the first. That’s because when you first took the files to the second computer it was the first time it had seen them, so it was uploading the XMP files to the LR catalog. But if you go back to the first computer and plug in your external hard drive, the files will not automatically update all the changes you’ve made. The good news is that Lightroom will see that you’ve changes, it just wants to ask you first, before it updates them. 

Importing External Changes


Let’s say you take your external hard drive back to your first computer. You were careful to save all the changes you made on the second computer to the XMP files. When you plug in your external hard drive you aren’t going to import them, because you already imported them the first time. This time you’re just going to go to the photo in your catalog to find a small icon on the upper right-hand corner of the image. The icon changes depending on the version of LR you have, but if you hover over it, a text will show up explaining that the image has been edited externally. That’s great, those were your changes. Just click on the icon and a dialog will ask you if you want to import the settings or overwrite them. You want to import the changes. If you make more changes, just make sure you’re saving the meta data to the file and you’ll go through this song and dance again every time you go back and forth. 

When LR detects the changes to the XMP file from another computer, this icon will alert you.

"Import Settings from Disk" updates your image with the changes you made on the other computer. "Overwrite Settings" erases the changes made on the other computer and restores the photo to what it was on this computer.

Manually vs. Automatically Writing Changes to XMP Files


For photographers with massive catalogs or slower machines, turning on the “Automatically write changes to XMP files” will negatively impact LR performance. That’s why Adobe has the feature turned off by default. If you are concerned about performance, then you can save the information to XMP files only when you want to by doing it manually. Simply go to the library tab in grid mode and right click on the files you wan to save the info to XMP files. Under metadata, select “Save Metadata to File”. Bam! You’re good to go. 

If you're not set up to automatically save XMP changes, you'll have to do it manually by selecting "Save Metadata to File"

Be Mindful of Your File Locations


Most photographers probably have LR import settings to automatically copy or move the files on import from the source card or hard drive onto a default location on their computer. That’s fine, but there could be problems. LR doesn’t like to delete files on import so if you are copying the files instead of adding them, then you are creating duplicates and that could create a headache if you’re not keeping track of what files you’re working on and which ones are duplicates.


I’ve personally found that keeping my files on a fast external SSD with USB 3.0c makes the whole process really easy. I make change on one machine and take it to the next, and both machines know that the files are on the external drive. How do you keep things simple?


When you import your files the first time from your camera, save them right to a high performance external Solid State Drive (SSD) and avoid external Hard Drives (HDD). That’s because if your drive is fast enough, you don’t even have to move the files off the drive and onto you computer. You can keep them right on that external SSD. Then when you take them to your second machine, import them so that they are added to your catalog and stay right where they are on the SSD instead of copying them to a new location and created potentially confusing duplicates.  

Don’t Rename Files!


If you have your LR set to rename files names when you import them, turn that mess off. Going back and forth between machines requires that each computer can recognize the files despite the changes you’re making. If you rename the files on one computer, when you take them to the next, your LR catalog will assume they are different files and suddenly you’re dealing with duplicates. It will work, but you’ll be doubling your images every time you do.

What are XMP files anyway?


Raw files come as a couple. The actual image is the CR2 or RAF or something similar, but it is paired with a much smaller XMP file that include additional information for the raw file. If LR doesn’t see the XMP file, it will create one for it. No RAW file should live life alone. Well actually, the XMP file is a bit of a translator for the RAW file. Sure you took a photo of the ocean, but what was the color balance, the tint, the camera used, etc.? The XMP has all that info. The changes you think you’re making to the RAW file when you edit them are actually being made to the XMP file. Now when you import them to Photoshop, you’re still not working on that RAW file because photoshop will create a new TIFF or PSD file to work on. So you’re never actually changing the RAW file. 

RAW files dont like to be alone. They need an XMP to help carry all the extra data they dont want deal with themselves.

What do you think?


I’d love to update this article based on your feedback. If you run into any problems or have questions, I’d love to know!