Impact of Converting to DNG


Today’s Question: Years ago, I thought it would be easy to give up the XMP sidecar [files associated with my proprietary raw captures] and started converting my raw files to DNG as part of my workflow. Am I losing something by doing this?

Tim’s Quick Answer: When converting to DNG you will retain your source capture data and the metadata you’ve added. You may, however, be giving up some proprietary metadata from your camera, and creating a minor issue with your backup efficiency.

More Detail: While you won’t lose any actual image data when converting a proprietary raw capture to the Adobe DNG (Digital Negative) file format, you may lose some proprietary metadata from the original capture. This would relate to special features of your camera that result in custom metadata being added, and that require software from your camera manufacturer to make use of.

For example, one of my cameras has a built-in dust removal feature. When I enable this option, the camera records data about dust on the sensor at the time of capture and embeds that information in the private metadata for the photo. Other software such as Photoshop and Lightroom are not able to make use of this information. Instead, you would need to use the software from the camera manufacturer to make use of that proprietary metadata, such as in this case to automatically remove dust spots from the image.

If you convert that proprietary raw capture to the Adobe DNG file format, you will likely lose any proprietary metadata. I say “likely” because there is an option to embed the original raw capture in the DNG file, but to me that would eliminate much of the benefit of converting to DNG, since the file size would be about double what it otherwise would be.

With metadata stored in the DNG file rather than an XMP “sidecar” file associated with a proprietary raw capture, your backup workflow may be affected as well. When you apply metadata updates, your backup software may need to copy the entire relatively large file for each DNG file you updated, rather than only needing to back up a small XMP file for each proprietary raw capture that you updated, since in the latter context the proprietary raw capture file would not have been updated.

So, overall, I would say that I still prefer to retain the original proprietary raw captures from my camera rather than converting to the Adobe DNG file format. That said, if you prefer to convert you aren’t risking the loss of too much information that would be of concern.