Lightroom: The Case Against DNG

category: Lightroom • 3 min read

Adobe created the DNG format: Digital NeGative, we are at version 1.3. According to Adobe:

Key benefits for photographers:

  • DNG format helps promote archival confidence, since digital-imaging software solutions will be able to open raw files more easily in the future.
  • A single raw processing solution enables a more efficient workflow when handling raw files from multiple camera models and manufacturers.
  • A publicly documented and readily available specification can be easily adopted by camera manufacturers and updated to accommodate technology changes.

Key benefits for hardware and software manufacturers:

  • DNG removes a potential barrier to new camera adoption, since raw files from new models will be immediately supported by Photoshop and other applications.
  • The DNG format allows R&D savings by reducing the need to develop new formats and by simplifying camera testing.
  • A common format allows greater control over the quality of conversions by third-party applications.
  • The specification allows the addition of private metadata to DNG files, enabling differentiation.


I’ve have used the DNG format for 2 years and now it has become a real pain… I have over 20,000 photos in the DNG format and I only have problems with these photos. I converted these photos to DNG because once I lost a bunch of XMP sidecars and there is no XMP sidecar when dealing with DNG images.

What Adobe doesn’t tell you:

  1. There are 2 different DNG formats

    The DNGs created by the Adobe converter and the DNGs created by the camera manufacturers like Pentax, Leica and Phase One. The DNGs created by the cameras are not compressed, while the DNG files created by either the Adobe Converter or Lightroom/Camera Raw are compressed.

    Once the photos are converted by Adobe’s converter, Lightroom or Camera Raw/Photoshop, no other software can read these files. You are locked in Adobe’s software.

  2. Once the conversion is done, the DNG file is frozen. With the “regular” raw image, whenever you upgrade your software, there are usually improvements in the processing of the photo, like better dynamic contrast, better noise handling, improved camera support… Not so with the DNG images.

  3. DNG is very slow.

    Lightroom or the DNG Converter do not transform the raw photo into a DNG photo, they create copies, and it’s very slow to create the DNG copies. It also takes twice the disk space when creating the DNG file.

    If you thought that rendering 1:1 previews was slow, updating the DNG built-in preview will make the rendering of 1:1 previews look like a race car zooming by. It’s between 5 to 10 times slower. It’s another operation that is not required by the “regular” raw images.

    Updating the metadata in the DNG files is about 2 to 4 times slower than updating the XMP sidecars. 1. There are 2 ways of converting from a RAW image to a DNG, the Adobe Digital Negative Converter and Lightroom/Camera Raw. The DNGs are different! With the Adobe Digital Negative Converter you can include the original raw image, but I haven’t found a way of doing it in Lightroom/Camera Raw. Therefore, I lost almost 20,000 original files that I can’t re-process with LR3 and its much-improved 2010 Process.


  • It’s possible to include the raw image inside by setting the Preferences > Import DNG Creation > Embed Original Raw File.
  • The raw image included in the DNG is only used to storing. It is just compressed inside the DNG file.

Why did I “lose” the originals? I didn’t know then. Now I do, but it’s too late for these 20,000 photos.