Today’s Question: I’m still not clear about the pros and cons of converting RAW files to DNG in my workflow. Can you clarify?
Tim’s Quick Answer: The primary advantage of converting raw captures to the Adobe Digital Negative (DNG) format is to avoid the use of proprietary file formats that may not be supported in the long term. The primary disadvantage is the risk of losing access to certain features that can only be accessed by using software from the camera manufacturer in conjunction with a raw capture file.
More Detail: My personal view is that the advantages of converting to the Adobe DNG format are not so compelling that I’m willing to discard my original proprietary raw captures. That said, there are some advantages to consider if you’re thinking about using the DNG format in your workflow.
One of the primary reasons the Adobe DNG format was created was to address concerns about proprietary raw capture formats that might not be supported in future software or operating systems. The DNG format is openly documented, so that even if Adobe discontinued support for the format other software developers could provide solutions. Seeing how a number of software developers (including Adobe) have reverse-engineered raw capture formats to provide support, this isn’t a significant concern in my view.
Another potential advantage of the DNG format is that the file size will generally be somewhat smaller than the raw capture it replaces, based on lossless compression. This can often reduce the file size by about 15% or more, which can obviously have a significant impact when dealing with a large number of photos.
The DNG format is also touted as not requiring an XMP “sidecar” file, because metadata is saved within the DNG file. While this does provide consolidation, there are also some drawbacks to this, such as requiring more time to perform an incremental backup because the updated DNG file is significantly larger than an updated XMP file.
The main drawback of converting to DNG is that you’re potentially losing the original raw capture data. You could always keep both files or embed the original raw capture in the DNG as part of the conversion, but to me both of these options take away some of the key advantages of converting to DNG in the first place.
For most photographers under most circumstances, converting to DNG probably won’t cause them to miss out on any important data. But if you use certain features of certain cameras, such as the automatic dust spot removal supported by some Canon cameras, you need the proprietary raw capture to be able to make use of the feature.
All things considered I don’t see any compelling reason to convert proprietary raw captures to Adobe DNG. But I also don’t think there is any significant risk in doing so for most photographers with a typical workflow. But on balance, I prefer to retain the proprietary raw capture format and not convert those images to DNG.
