I think I just have a hard time understanding the workflow when DNG is the primary file format and file I will be using. I won't be creating a PSD or TIF.
I understand that the original RAW data is in the file and can always be reverted to.
So it just seems strange to me that if I significantly or radically change a DNG that I don't create some kind of version like a xxxx-xxx-master-bw.dng.
How do DNG virtual copies fit into the system? Should I use or avoid them?
DNG is just a container, a high end TIFF if you will. It can hold raw data (in a non proprietary format), or rendered data. The later is a tad confusing because originally DNG was to hold raw data hence the name "Digital Negative
". So just think of DNG as another raw format although the data inside the DNG doesn't have to be raw. When dealing with raw in the DNG, the raw itself isn't altered. Just as when you make a print in the darkroom, the negative isn't affected.
What you are doing is creating instructions about how you want to render
the data TO a TIFF or JPEG or PSD from the raw. How should the raw be used to produce RGB pixels, in some color space, with some kind of color appearance? Going back to the darkroom, think of the raw being the negative and think about altering the controls on the enlarger to get a different looking print (the instructions).
With a Virtual Copy, you are kind of creating a copy of the DNG without having to save another raw (or DNG) to disk. Since the original raw data isn't touched, you are telling Lightroom, make a 2nd set of instructions, go to the raw data and show me another iteration of what I could
end up with IF I render the raw and these instructions. One thing to keep in mind is the VC lives in the LR database. So you can have one
raw document, DNG or proprietary raw and a dozen sets of instructions. You create instructions which are basically text files which take up a tiny amount of space.
If I end up with a VC that is my hero, I can if I so desire export this as another DNG. Now that iteration isn't living solely inside the LR database. It is a standalone document that has the raw data and those instructions, plus a lot of other useful components (DNG profile for example). Probably not necessary but for a belt and suspenders backup schema, another option.
At some point you may
want a PSD or better IMHO, a TIFF. If you wanted to take it into another application like Photoshop or Graphic Converter etc. IF you plan to live totally in LR, even printing there, probably no need to be creating a PSD or TIFF. LR can do everything with the DNG: build a slideshow, a web gallery, make a print etc.