Today’s Question: With respect to the [April 10th] question/answer [about deleting previews in Lightroom Classic], if previews are deleted to recapture disk space, does metadata still remain with the photos so that using search criteria, one could still locate the photo and restore the preview?
Tim’s Quick Answer: Yes, discarding previews in Lightroom Classic will not cause any metadata to be lost, either in the catalog or in the source files on your hard drive. Discarding previews simply clears the image from the cache, and a preview will be built again the next time you browse the photos.
More Detail: The Standard and 1:1 previews in Lightroom Classic are simply a cache to enable faster browsing of photos, and as such there is no serious harm caused by discarding previews. The only drawback to discarding previews is that the next time you browse the affected photos there will be a brief delay in rendering the preview. That generally results in a preview that looks a bit soft at first, and then improves in quality once the preview is built.
Discarding previews will not remove any metadata from the Lightroom Classic catalog, nor will it cause metadata saved to the source images to be lost. That includes both metadata saved to standard image formats such as JPEG and TIFF, as well as metadata saved to XMP sidecar files for proprietary raw captures.
Therefore, it is perfectly safe to discard previews for selected photos (or even all photos in the catalog) by selecting the applicable photos and going to the menu and choosing Library > Previews > Discard Standard and 1:1 Previews. It is even safe to delete the previews file associated with your catalog to quickly free up a large amount of storage space, though I don’t recommend doing so unless you’re confident you are very familiar with which files in the catalog folder are critical and which are safe to delete.
