The Problem:

In my office I use an iMac when working in Lightroom. But when I’m on the road traveling, I like to work in Lightroom on my MacBook Pro. (Ok, I admit it… I often work on my MacBook Pro while relaxing in my recliner too.) The issue I had been having though was trying to keep my Lightroom Catalog file in sync so that whenever I edited photos while using my laptop, all of my development adjustments, keyword tags, and various other adjustments would be visible the next time I worked in Lightroom on my iMac.

I first thought the solution would be to have both instances of Lightroom reference the same catalog file. For example, I would create a Catalog file on my iMac and then direct the copy of Lightroom on my laptop to use the Catalog file on my iMac over my LAN. Unfortunately though, Lightroom doesn’t allow you to reference a Catalog file on a networked folder. If you try to do it, Lightroom will popup an error box and won’t even allow you to try it.

What I had been doing instead was to always try to remember that whenever I started working in Lightroom on either computer, to always right-click on my latest 5-10 folders and choose the “synchronize” option. This would at least make it so any new photos I might have imported on either computer would appear. For example, if I imported 10 new images into an image folder being referenced on my iMac’s Lightroom catalog, they would then show up as being visible when I worked in Lightroom on my iMac.

The problem with trying to synchronize with this method was that it wouldn’t transfer over any of the meta data, such as any development adjustments or keywords I had added. Worse yet, the thumbnails would often have an exclamation point icon over them, indicating that the meta data didn’t match, and would offer me the option to overwrite or update it. I could never remember which option to choose, but seemed to always choose the wrong option, which would end up wiping out any of the development changes I had previously made to the photo for good.

The Solution:

I’ve been a big fan of Dropbox for several years now, and have used it to synchronize files from other programs but never thought about using it with my Lightroom Catalog files. I take that back… I think I thought about it, but not being very familiar with exactly how Lightroom worked in the past, I likely assumed it would cause Lightroom to slow to a crawl since I would be working on very large image files.

But now that I’d become a lot more familiar with how Lightroom functions, I realized that the Lightroom Catalog file is really just a set of instructions that tell the program where things are located and what adjustments have been made to them. Also, because the Dropbox folders created on each computer are seen as just local folders, Lightroom won’t prevent you from accessing a Catalog file stored in a folder because it won’t see it as a network folder.

How To Do It:

This is actually the easy part.

• Assuming you already have a Dropbox account, create a new folder within your Dropbox local folder and name it something such as “Lightroom”.
• Make a copy of your existing Lightroom Catalog file and then transfer it to the new folder you just created. (Make sure to copy the Lightroom Catalog file that is the most up-to-date instance. In my case, it was the version on my iMac.)
• Once the Catalog file has been copied over, you need to instruct Lightroom to begin referencing this file. To do this, hold down the option key while opening Lightroom. Instead of starting up as usual, you’ll be presented with a dialog box asking about your catalog. Choose the option of “Choose a Different Catalog”.

• Navigate through Finder and find the Catalog file you just copied over to the new folder in Dropbox.
• Before closing the dialog box, make sure the option “Always load this catalog on startup” is checked.

• Lightroom should then startup and appear identical to the way it had been appearing prior to making all of these changes.
• If by chance all of your thumbnails are blank and have a question mark icon on them, it’s because the path leading towards your image files is no longer correct. Click on 1 of the question mark icons and then navigate to where that particular image file is located. Once you find and select it, Lightroom will likely update the path for all of your photos and you’ll be back in business.

Additional Tidbits/Info:

• Whenever you start up Lightroom, you’ll notice it creates a couple of additional files within your new Dropbox folder. One of them will be the name of your Lightroom Catalog file appended with “Previews.lrdata” and the other will be appended with “lrcat.lock”.The “Previews.lrdata” file is where Lightroom caches the thumbnail preview data, which helps to speed up the viewing of your thumbnails.This file will vary in size depending on how you set your Lightroom Preferences. If you setup your preferences to never delete preview data, this file will be rather large and will continue to grow indefinitely. I have mine set to delete preview data after 1 week and my preview file varies around 200-250mb.The “lrcat.lock” file is a safety mechanism built in so that you don’t accidentally overwrite your Catalog file should you not shut down an instance of Lightroom before opening another instance referencing the same Catalog file within your Dropbox folder. Whenever you close down Lightroom, this file automatically deletes itself.

• To avoid having any type of conflicts with your Catalog file, just be sure that whenever you’re done with Lightroom, that you shut it down. This will properly update/finalize your Catalog file and cause the lock file to disappear. Before opening up any other instance of Lightroom that is accessing the same file, make sure it has fully synced with the Catalog file you last closed. Most of the time, this takes less than a minute over your LAN and less than 3-4 minutes to the Dropbox cloud.

Common Questions/Answers:

Here are answers to some of the questions I think you’ll likely have:

Will this slow down Lightroom?
It shouldn’t slow down Lightroom because it’s referencing a Catalog file that is stored locally on your machine. The way Dropbox works is it writes/saves the files to your local machine first, then it syncs over your LAN to other Dropbox folders and then finally it syncs to the Dropbox folder in the “cloud”. Lightroom doesn’t have to wait for everything to be in sync after each adjustment you make.

Should I store my image files in one of my Dropbox folders?
I wouldn’t recommend this because your image files likely take up a large amount of space and most people only have a free Dropbox account, which limits your storage to 2GB.

What if I forget to shut down an instance of Lightroom and open another instance on my other computer?
If Lightroom hasn’t been shut down on one instance, the lock file will still be in place. So when the other instance of Lightroom is started, it will see the lock file and will create an additional catalog file named something like “conflict copy of…”.

If you continue using the 2nd instance of Lightroom, any adjustments you make will be stored in the conflicted copy version of the Catalog. You’ll then have to get into your detective mode and figure out if it’s worth going through your conflicted Catalog file and exporting out the changes you made into your primary Catalog file. This is a major pain, so just do your best to avoid this situation.

What if I’m using Lightroom on my laptop while out of town and I don’t have an internet connection? Will I have to leave Lightroom running until I get an internet connection?
Keep in mind that Lightroom is referencing a Catalog file on your laptop’s local drive, which is there regardless of whether or not you’re connected to the internet. You can work on images inside of Lightroom and close down Lightroom whenever you want without corrupting the Catalog.

The thing to be careful about though is that before you open Lightroom on your other computer, to make sure the Catalog file has synced with the version of the file on your laptop.

Why don’t you instead just place all of your image files and your main catalog file on an external hard drive, which you then plug into the computer you’re currently working on?
This is another way to accomplish the same thing. If you’re comfortable with having to remember to bring your external hard drive with you, then that method is fine. An added benefit though of using the Dropbox method is that you’ll always have a backup copy of your Catalog file in the Dropbox “cloud”.

Scott, you’re just now realizing you can sync your Lightroom Catalog file on Dropbox?
Umm, yeah. I realize many other people have already figured this out on their own and that I’m not the first to write a tutorial on how to do it. But for those who keep up with me via my blog who don’t know about it, I thought it would be helpful to write about it. If it helps only one extra person, it’s been worth it.

Why do you only provide instructions on how to accomplish this on a Mac and not also on a PC?
I own several Macs and therefor explained how I accomplished something on my Mac. But if you really want to know how to do this if you’re using a PC, then replace the word “option” with “control”, the word “finder” with “explorer” and add 3 hours of additional troubleshooting time. (Sorry, I had to say that.) :)

Why aren’t you using an affiliate link when linking to Dropbox? Don’t you know that you could be earning extra storage space on Dropbox for each new person you refer?
Yes, I’m aware of this. But I’ve already paid for extra storage on Dropbox, which is more than enough space than I’ll ever need. I didn’t want this tutorial to come across as a way for me to just get some extra space. However, if you’d like to signup for Dropbox via my affiliate/referral link, click here.