Today’s Question: It takes me longer than 30 days to be finished with my 1:1 previews in Lightroom [Classic CC] so I have to delete them manually. When photos are in a stack within a folder and I delete the 1:1 previews for that folder, are the 1:1 previews of the images in the stacks deleted?
Tim’s Quick Answer: Photos that are in a stack will only be selected (and therefore affected by deleting the 1:1 previews) if the stacks are expanded for the folder before you select the images within the folder. Note, however, that you also have the option to remove 1:1 previews for all photos within a folder, even if you did not select all of those photos initially.
More Detail: Lightroom will generate a 1:1 preview for an image when you zoom in on the image. You can also generate these full-resolution previews during import, or later in your workflow using the command found on the Library > Previews submenu.
By default Lightroom will remove 1:1 previews if you have not accessed them within thirty days. In addition, you can choose to have those previews discarded after one week or one day, or to never discard the 1:1 previews automatically. This setting is found on the File Handling tab of the Catalog Settings dialog in Lightroom.
If you want to retain 1:1 previews longer than thirty days, you can select the “Never” option from the “Automatically Discard 1:1 Previews” popup in the Catalog Settings dialog. You can then choose when you want to discard those previews manually in order to free up hard drive space.
So, when you are finished with your review work for a given folder, you could select all images within the folder that you want to remove the previews for. If you want to remove previews for all images in a folder, you don’t actually need to select all of the photos first. Simply choose Library > Previews > Discard 1:1 Previews from the menu, and in the dialog that appears choose the option to discard previews for all images in the folder rather than only the selected images.
If you want to remove these previews for only certain photos, you do need to select those photos individually first. If some of the photos are in stacks, you do need to select all of the images within the stack, rather than only selecting the stack itself. You can streamline this process by expanding all of the stacks within the current folder. To do so, go to the menu and choose Photo > Stacking > Expand All Stacks. You can then select the specific photos you want to remove the 1:1 previews for, and then select the menu command to actually discard previews for the selected images.