Smart Previews in Adobe Lightroom

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May 10, 2021
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I’m going to begin this post with an example of a situation that’s not ideal. Let’s say that you’re a photographer who primarily works on a laptop and who stores your photographs on an external hard drive. If you recall, it was recommended you store everything on a backed up external hard drive in a previous post. The reason you use an external hard drive is because those drives can have HUGE storage capacity that’s getting larger every day. Your laptop pales in comparison. The thing is, you do a lot of traveling and while you travel, you like to edit photos in Lightroom (on your laptop). The other thing is, you don’t particularly enjoy lugging your behemoth external hard drive with you when you travel. So, what do you do? How can you edit your photos while they’re not physically tethered to your laptop via an external drive?

Enter Lightroom Smart Previews​

I think I should explain how things work behind the scenes after you import your photos into Lightroom. It’s sort of confusing, so it bears some clarification.

After you complete the initial import steps and after you set all the panels they way you’d like to see them, you click the “Import” button. At this moment, you wait a few seconds while Lightroom does it’s thing as it “imports” your photos into the program. When complete, there you sit at your desk thinking that you just, somehow, placed your desired photographs into the actual program called “Lightroom.” You think that either Lightroom took the photographs and physically moved them someplace other than their original location or, at the very least, copied them there. Now, with this knowledge, you can begin your editing.

Now, the scenario above isn’t completely true or completely false. After you clicked the “Import” button, Lightroom did do some shuffling. Just not the way you suspect. While Lightroom recognized the original location of your images and create some thumbnails to store near your catalog (which we’ll discuss in a later post), it didn’t move any of your original photos. All it did was create a “link” to those large images so that it can apply any changes you make in the program to them. The images are still in their folders they call home.

You may be asking what the problem is. And if you’re on a desktop where you generally don’t unplug your external hard drive or if you store your images on your local internal drive, the answer would be “nothing.” You don’t even have to read this post any further. But what if you, as I mentioned in the intro to this post, disconnect your external drive from your computer, whether it be a desktop or a laptop? You can probably guess – you’d sever the link Lightroom has made to those big juicy images and all you’re left with are those tiny thumbnails that Lightroom stored in the same folder as its catalog. Can you imagine trying to edit thumbnails? I can’t.

Because of the popularity of working on the go (airplanes, trains, buses) and because of the hassle of hauling your external drive with you, Adobe has created a magnificently handy feature called “Smart Previews.”

What Are Smart Previews?​

Basically, Smart Preview images are a fraction of the size of your original files. When you create Smart Previews during initial import or later on after your files are imported, the process of which we’ll discuss next, Lightroom not only creates the link between it and your original files, it also creates smaller Smart Preview files to store right next to your catalog ([Catalog Name] Smart Previews.lrdata file, located in the same folder as the catalog.). These smaller files are simply miniature, lightweight images that have been converted from whatever format you originally shot your photographs as to Adobe’s DNG format. But while they’re only a fraction of the size of your originals, they’re large enough to clearly view and edit. And, as I mentioned, they’re stored in their own file inside of Lightroom, so it makes no difference whether or not you disconnect your external drive. You’re still able to edit your photographs wherever you go.

By now, I’m sure you have a few questions. If I were you, the questions I would have are:

1. If I’m only editing smaller previews of my original images, how do my large images get edited?

2. Yeah – this sounds great – actually a little too good to be true. What’s the catch?

I know. Nothing comes without strings. I’ll answer your questions one at a time.

If I’m only editing smaller previews of my original images, how do my large images ultimately get edited?

As you go about editing the Smart Preview files, Lightroom stores all your edits in its own little database file. It remembers everything you do. When you’re finished and after you connect the drive with your large files back to your computer, Lightroom applies the stored changes to them. It really is wonderful.

Yeah – this sounds great – actually a little too good to be true. What’s the catch?

There is a downside to using Smart Previews. Since Lightroom stores the preview DNG files in its own file, after a while, or with just one large shoot, that file can become huge. While it won’t become as huge as if you tried to import all your originals to their own file, it gets pretty big. Adobe’s example states:

For example, 500 raw images from a high-end DSLR camera may occupy 14 GB of disk space. The Smart Preview files for the same images amounted to 400 MB of disk space.

It’s of my opinion that by having one file that’s over 400MB, you’ve got a pretty large file. I’m not sure I would want that. Personally, I would take advantage of the Smart Previews feature in small doses.

How To Create Lightroom Smart Previews​

Enough of this background. Let’s get to the fun stuff. Let’s go over exactly how to import some Smart Previews.

Luckily, creating Smart Previews is super easy. While going through the process of importing your images, all you need to do is check the “Build Smart Previews” box in the “File Handling” panel in the right column.


Once this is completed and after you’ve got everything else set, you can go ahead and click the “Import” button down at the bottom of the right column.


There you have it. Once your photos are imported, you should be presented with a small popup just a few seconds after that. Inside the popup, Lightroom indicates that it’s created however many Smart Previews of the images you brought in.

How Do I Know If My Smart Previews Were Really Created?​

If you’re wondering how you can tell which photos are accompanied by Smart Previews, you can simply click one of the images that’s been imported and take a look at the top portion of the right column. Directly under the histogram, if the image you’ve clicked on has a Smart Preview, you should see some text that states “Original + Smart Preview.”


Creating Smart Previews After Your Photos Have Already Been Imported​

Let’s say that you never knew that you had the ability to work with Smart Previews and you’d like to get going with this feature. Or, let’s say that you simply forgot to check off the little “Build Smart Previews” box in the “File Handling” panel in the right column during import. Either way, you’ve got images that have already been imported and you really want to work with Smart Previews. How can you go about doing that? This one is super easy as well.

All you need to do to generate Smart Preview files for images that have already been imported is to make sure you’re viewing your imported images in grid view. Once that’s done, you simply check off the pictures you’d like to create a Smart Preview for. If you’re not familiar with checking pictures off, please read the “Importing Pictures To Lightroom” post.

After all your desired photos are checked off, head up to the “Library” dropdown in the top menu and roll over the “Previews” menu. From there, you should see some choices. Click the “Build Smart Previews” selection and you should be good to go. The same exact operation should occur as if you had done this during import.


How To Delete Smart Previews​

The only reason I created the Smart Previews that I did was to use them as an example for this post. I really didn’t want them. I know they are taking up space in my computer and I try to keep things as tidy as possible. So, with that said, I’d like to delete them. You may want to accomplish the same task for the same reason. Either that, or you’ve finished your edits and no longer need the previews. That’s a good enough reason for me.

To delete Smart Previews, you’ll need to select the images that you’d like to remove the Smart Previews for. You can either select each image individually by clicking on it or, if you’ve got a series of images, click the first one and hold down the “Shift” key on your keyboard. While you’re holding down Shift, move down to the last image in the series. If you click on that one, you’ll see that you just selected everything in between the first and last image.

Once your images are selected, head back up to the “Library” dropdown in the top menu and roll down to the “Previews” selection. From there, click the “Discard Smart Previews” selection. After that, all your Smart Previews for your selected images should be gone.