Another type of preview that you can add to your photos is a smart preview. This allows you to continue editing your photos even if the main hard drive where those photos belong is disconnected.
For example, let’s say that you have a laptop as your main computer at home or at work, and let’s say that you also have an external hard drive where all of the photos from your Lightroom catalog are stored. Without smart previews, once you disconnect that hard drive, you get a question mark next to the folders and that hard drive saying “I don’t know what
happened to these photos. I can no longer see them.”
Smart previews, however, allow you to continue working on those photos even when you’re offline and disconnected from that external hard drive.
For example, I have an external hard drive connected to my computer with photos imported into my catalog. But let’s say I’m working off of a laptop and I want to take the laptop to a coffee shop and just sit down and get some work done and maybe process some of my photos but I don’t want to take the hard drive with me.
What I would do is I would select all of these photos or whichever photos I wanted to work on, go up to Library, Previews, Build Smart Previews.
Depending on how many photos you’ve selected, this may take a few minutes. Lightroom just finished making those smart previews, and a window pops up to tell me that it’s finished.
I’ll go ahead and click OK, and if I look over on the right just below the histogram, the rectangles with the numbers next to them will tell me how many photos of each type that I have selected in this folder. If I hover over, it will explain which is which.
But what happens when I eject the hard drive? I’m going to right-click over that hard drive in the Folders list and select Show in Finder and then I right-click over that icon and eject that hard drive. Back inside of Lightroom, all of these photos are still here.
In the Folders panel, that folder looks like it’s missing, but none of the images have the exclamation mark next to them indicating that they’re a missing file. Instead, they have a little smart preview icon at the top right. If I click on it, a window pops up telling me that it’s a smart preview, but it’s not the original file, and I know that, I’m aware of that because I intentionally ejected that hard drive.
But now I can take this image into the Develop module, and it lets me edit the photo.
So now let’s see what happens when I plug the hard drive back in. Under the Folders panel on the left, that hard drive reappeared and there’s no longer a question mark next to that folder. Also, the photo that I was working on retained those edits.
So building smart previews is a really good way for you to continue working on your images even if the hard drive that they’re located on is temporarily disconnected. And that’s why we use them to edit your photos.