I’ve been using Lightoom as my main photo editing and managing system for a long time now – it even precedes my Macification. In all that time, I’ve worked in a particular way. I keep my main photo library – that’s the actual image files and the Lightroom catalog – on my iMac and a separate library on my MacBook. When I go away, I take the MacBook and import photos into its library. When I get home, I do an “import from other catalog” on the iMac, so all my new images and any edits I’ve made join the main library.
This works well enough, but it does mean that while I’m travelling, I have no access to my older images. And as the MacBook doesn’t have the capacity to carry a copy of my images, that seemed like an unavoidable thingy.
But several versions ago, Adobe added a feature called Smart Previews to Lightroom. These are sort of medium quality versions of the images – not in the full resolution of the original files, but good enough for most editing work, and large enough for exporting to websites (though not for most printing jobs). You can tell Lightroom to create these when importing images, or you can get it to generate them for your existing library. The former is a good idea – note that if you have a lot of images, generating the Smart Previews is a “go away and let it get on with it” kind of job. You should also note that they will take up a moderately significant amount of disk space, though crucially, much less than the original image files – as an example, my library of just under 73,000 image files – a mixture of JPG and RAW – ended up needing about 60GB for the Smart Previews. Sounds like a lot, but compared to well over 1TB, it’s not so bad.
Now comes the clever bit – Lightroom can happily work with Smart Previews if the original image files are offline, so if you were to get the catalog and associated previews and smart previews onto a second computer, you’d be able to view, edit and even export images without having access to the original files.
No, now comes the clever bit – if you were to move your catalog and its associated files to a nicely synchronised cloud service such as Dropbox, you’d be able to open that catalog from your other computer, work on things and have access to all your images. All you’d have to do when returning from a trip is to copy your new images to the main computer and tell Lightroom where they live in the usual way.
So, I decided to give it a try.
Generating the smart previews took a while, as did copying the catalog and its associated files to my Dropbox folder. An interesting point is that, on macOS at least, you’ll see what appears to be a file called <catalog name> Smart Previews.lrdata. This is actually a folder containing numerous subfolders which eventually contain the images. And the size displayed for that file may be a wild underestimate (it was originally showing as around 4GB on my iMac). Once it was copied over, it was a matter of waiting for it to complete uploading to Dropbox. And then I could test it, and woo, hoo, it works.
So, I now have a Lightroom catalog on my MacBook that lets me see any of my photos.
Things to be aware of – you must let Dropbox sync changes made on one computer before attempting to use the catalog on another, otherwise Bad Things may happen to your data. And make sure you back up regularly. You do back up, right?
Just to prove it, here’s an image that lives on my iMac, edited on my MacBook, and it never felt a thing.
Shutter speed: 1/60s
Focal length: 18.5mm
Taken: 2 December, 2017
 The iMac is a bit awkward on trains
 I take a while to catch on sometimes
 I’m not convinced iCloud Drive will play nicely with this, as it’s a bit too “clever”. Dropbox does work as it syncs the individual files in the smart previews folder