Today’s Question: I keep all my photos on an external hard drive. Is there a way I can still edit my photos in Lightroom Classic when that drive isn’t connected?
Tim’s Quick Answer: Yes, you can enable editing of photos in the Develop module even when the source image isn’t available by building Smart Previews for the photos.
More Detail: When the source photos for images being managed by Lightroom Classic aren’t available, such as when the external hard drive containing those photos isn’t connected to the computer, there is still a lot you can do within Lightroom Classic. For example, you can review and update metadata, add keywords, assign star ratings, and more. However, by default you’re not able to apply adjustments in the Develop module or export copies of photos when the source files are unavailable.
However, if you build Smart Previews for your photos, you can continue to work in the Develop module and export reduced-resolution copies of the images, even when the source files aren’t available.
There is an option to build Smart Previews during the process of importing photos into Lightroom Classic, but if you didn’t make use of that option, you can still do so after the fact. Make sure the source files are available (such as by making sure the external hard drive is connected) and select the photos you want to build Smart Previews for. Then go to the menu and choose Library > Previews > Build Smart Previews.
Once the Smart Previews have been built, you’ll be able to work with the images in the Develop module or export copies of the images at a reduced resolution, even when the source files aren’t available, based on the Smart Previews that are stored along with the catalog files for Lightroom Classic. Note that because those Smart Previews are DNG images at a reduced resolution of just over 2,500 pixels on the long side, they won’t have the full fidelity of the source images when working in the Develop module or when exported for sharing.
