Today’s Question: Can you explain what’s the difference between building a Smart Preview versus a Standard Preview when importing photos into Lightroom Classic?
Tim’s Quick Answer: A Smart Preview in Lightroom Classic is a high-resolution DNG preview of your source capture, enabling greater flexibility in your workflow. A Standard preview is a JPEG preview at approximately the resolution of your display. There is also a 1:1 preview option, which is a JPEG preview but at the full resolution of the source image.
More Detail: Lightroom Classic uses previews of your photos for various purposes, primarily as a cache to improve overall display performance and to enable you to view your photos even when the source files are not available (such as when an external hard drive containing your photos is not connected to your computer).
JPEG previews are used primarily in the Library module to enable you to browse your images more quickly (since the source raw capture does not need to be rendered, for example) and to enable you to browse your photos even when the source files aren’t available (since the previews are stored alongside your catalog).
The JPEG previews can be rendered at various sizes, with the primary options available being the Standard versus 1:1 previews. The 1:1 previews are obviously at the full resolution of your source photos, and enable you to zoom in with good quality even when only the preview is available. The Standard previews are sized based on the size (and quality) settings established on the File Handing tab of the Catalog Settings dialog, but are aimed at being approximately the resolution of your display so you can view the full image.
A Smart Preview is a relatively high-resolution preview (though not full resolution) in the DNG format rather than JPEG. This enables greater flexibility and improved preview quality.
Normally you aren’t able to work with your photos in the Develop module if the source image file is not currently available. However, if you have rendered Smart Previews of your photos you can still work in the Develop module even if the source file isn’t available. You can even export copies of your photos based on Smart Previews without needing to have the source files available.
There is also an option to use Smart Previews to improve performance in the Develop module by favoring Smart Previews over the source image file.
Personally, I don’t generate Smart Previews of my photos because I typically have the source images available and I’m not too concerned about improving performance somewhat modestly in the Develop module. Also, the Smart Previews are by their nature somewhat large in size, consuming quite a bit of hard drive space.
I also generate Standard previews rather than the 1:1 previews because I don’t tend to zoom in on my photos beyond full screen very often in the context of the Library module. In the Develop module the source image is being rendered, so the normal previews aren’t employed. Of course, as noted above you do have the option to use Smart Previews in the Develop module.
Of course, every photographer has different priorities in their workflow, so you may prefer to take a different approach than I do. The key is to understand the options available so you can make the best decision based on your own needs.