Previews are controversial, somebody will tell you that you should render them 1:1 on import of the photos. Somebody else will tell you that you shouldn’t generate the 1:1 previews.

  1. There is NO correct answer.
  2. It’s a preference.
  3. No matter what you decide, Lightroom needs the 1:1 previews. You will have to pay the piper, the only question is when. Will you pay at the front-end or at the back-end?

The 1:1 preview of the photo is used in:

  • The library module when you go to a high resolution enough, usually around 1:3 to 1:2 but that depends on the standard preview size as defined in the catalog setting.
  • The develop module: always.
  • The slideshow module when you go to a large enough slide.
  • The print module: always.
  • The web module: almost always, depending on the size of the photo behind the gallery.

Selecting to generate the 1:1 previews of the photos is a balance between:

  1. Available disk space
  2. Perception of speed

And the keyword here is perception. It always takes exactly the same amount of time to generate the 1:1 preview of a photo. The question is:

  1. Do you want to spend the time at import?
  2. Do you want to spend the time when you are working on the photo?
  3. Do you want to spend the time when your computer is idle?
  4. What’s the number of “almost” identical photos. 300 almost identical photos, and you select to Develop only 1 or 2 photo, then you only need the 1:1 preview only for these couple photos.

In the Library module, from the Library menu:

Lightroom: Generate Previews

Lightroom: Generate Previews



Lightroom: Generate preview for only 1 selected photo or all photos

Lightroom: Generate preview for only 1 selected photo or all photos

So what’s the correct answer? Your preferences! You will have to balance:

  • Your perception that Lightroom is slow
  • The available disk space
  • Your patience
  • Having these thousands and thousands of files, for your previews, on your disk.
  • How many of the photos do you need to process and develop?

My personal preferences:

  • For a few hundred photos: generate all the previews 1:1 at the import and keep them.
  • For a few thousand photos: generate all the previews 1:1 as an overnight job and keep them.
  • Storage is cheap, $40 Canadian per terabyte and it’s becoming cheaper every 3 months.
  • If you need space, all previews can be deleted from the same menu. Lightroom will regenerate them as needed.