Someone asked on Flickr if they should delete their camera raw files after converting to Adobe DNGs. Certainly you can see a strong pressure from Adobe to do so in order to save some hard drive space.
I don’t. Adobe’s DNG converter has the option of storing the original raw file along with it so I don’t see any theoretical harm in deleting the RAW file if that option is checked. Then again, since it increases the file size as much as two files stored separately, I don’t understand the advantage in that other than in file management for those who don’t have an adequate one (i.e. you are using Adobe Bridge or iPhoto instead of Aperture or CaptureOne).
The problem is that without this option checked can you reconstruct the original raw file from the DNG alone? I know of no tool that does this. I know of no incentive for one to be built by Adobe.1
So what? Well look at the DNG file, it is double the size of a compressed NEF (Nikon raw). Why? Because Adobe’s de-mosaic recipe has already been added/embedded with the RAW.2 What if I don’t like Adobe’s recipe?3 What if I’d prefer my vendor’s RAW conversion because they are aware of their own anti-alias/bayer filter and optical design assumptions in their lenses and bodies? What if I use a a 3rd party tool made by real optics engineers that adjust for lens and camera body defects? What happens as these RAW processing tools improve? What option do I have at that point?
I use DNG as part of my photo workflow because unlike TIFF, they can carry metadata. I store and archive DNGs along with the Nikon NEFs in Aperture. But will I don’t delete my NEFs.
And neither should you.