Today’s Question: You mentioned that Lightroom Classic can show previews of photos that are on a hard drive not currently connected to the computer, as long as previews had already been created. I’m not seeing previews for many photos when my external drive is disconnected, so how can I get Lightroom Classic to build previews for all photos?
Tim’s Quick Answer: If you need to build previews for all images in your Lightroom Classic catalog you can select all images from the All Photographs collection with no filter set, and then from the menu choose Library > Previews > Build Standard-Sized Previews.
More Detail: Lightroom Classic will build standard previews as needed, meaning if you are browsing photos that don’t yet have standard previews and the source images are available, Lightroom Classic will build the previews. There’s also an option to build previews as part of the process of importing new photos, which can be helpful in terms of ensuring you have previews available for offline viewing.
Once previews are built for images, you can use those previews as the basis of viewing your photos even if the source files aren’t available, such as when an external hard drive containing photos isn’t connected to the computer.
If you find that previews are missing for some (or many) of your photos, you can build those previews on demand. Start by selecting the “All Photographs” collection in the Catalog section of the left panel in the Library module. Then go to the grid view display and make sure the Library Filter bar is displayed above the thumbnails, choosing View > Show Filter Bar from the menu if the bar isn’t shown. Then choose “None” to ensure no filter is set, so you’re seeing all images.
You can then choose Edit > Select All from the menu to select all photos, which in this case would mean all photos in your entire catalog. Then choose Library > Previews > Build Standard-Sized Previews from the menu, and Lightroom Classic will get to work building previews for all selected photos (as long as the photos are currently available).
The process of building previews could take quite a long time (hours or potentially days) depending on how many photos are in your catalog, how many of them don’t currently have previews, and the overall performance specifications of your computer. Once those previews are generated, however, you’ll be able to browse all photos even if the hard drive the photos are stored on isn’t connected to your computer.
