Why use DNG instead of NEF (or CR2)?

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PhilBurton

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Adobe seems to be pushing us in varioius ways to use DNG, but I'm not convinced yet? I'm a relative newcomer to Lightroom so I'd like to tap into the wisdom of people with more experience than me:

  1. Does LR do a better job DEVELOPing a DNG as compared with an NEF?
  2. Does DNG include all the data in an NEF, including the Maker Notes? That is, do I lose any information if I convert my NEFs to DNG?
  3. For my images already in LR and DEVELOPed and PUBLISHed, can I still convert the NEFs to DNG? If do can do that, will I lose all the edit data?
  4. Can Lightroom recognize for cataloging purpose an NEF and a DNG of the same image? Does this make the catalog bigger?
  5. What are the advantages of staying with NEF?

Thanks,

Phil Burton
 

sizzlingbadger

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1. No, they are the same.
2. It includes all information.
3. Yes you can, edits will remain.
4. They are treated as separate files.
5. Other raw converters may not support DNG very well.
 
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1. No.
2. Yes.
3. Yes. You won't lose anything.
4. When you convert a NEF to DNG, The DNG becomes the catalogued file. You have a choice about whether to delete the NEF or not. If you don't the NEF stays in the same folder, but it won't show in the catalogue.
5. If you write metadata back to the images, it's stored internally in DNGs and in a separate "side-car" file for NEFs. If you back up changed files, a changed DNG is lots bigger than a changed side-car. I rely on the catalogue to keep the metadata, so that problem doesn't arise for me.
 
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In addition to what Nik has listed:
  • A DNG will contain a checksum which can be checked to let you know the DNG file is intact. This is viewed by some as a positive feature. Of course if you discover that the file is damaged, you will need a good backup to replace it with. Some may see this as a Plus for DNGs but there are other ways to discover that your RAW file is corrupt and you still need a good backup.
  • Converting to DNG on import slows the import process. Adobe has changed the Import process because of this. The import process is now in two stages. Importing the master original RAW files and cataloging these. This stage goes quite quickly. Then after the import is complete, the RAW file is converted to DNG for the latest import and replaces the NEF in the catalog then the original file is deleted.
  • You can not convert a DNG back to a proprietary RAW format. So if you need the original RAW, you need to save and back up that file along with the DNG.
  • You can embed the original NEF inside the DNG. This can be extracted later if need be.
  • Both of these last two items require nearly twice the storage footprint as the original Proprietary RAW file. So the perceived advantage that the DNG is a smaller file is lost.
  • If you create DNGs and keep the NEFs as you should, there is no housekeeping task to delete the original NEFs if you delete the DNGs in LR
  • Some people like to write their XMP adjustments back to the master file. If the Proprietary RAW file is the Master, a separate XMP sidecar file is created. With a DNG, the XMP can be embedded in the header. While the DNG keeps all of the data and most of the metadata together in one file, it also requires a new back up of the large DNG file for every update to the metadata. With a XMP sidecar, only the small XMP file gets included in the next back up.
AFAIK ACR takes as long to convert a DNG to RGB as it does a Proprietary RAW file.

There are two opinions on converting to DNG. Both have some validity. You need to decide if converting to DNG has advantages that are worth the trade offs.
 

PhilBurton

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1. No, they are the same.
2. It includes all information.
3. Yes you can, edits will remain.
4. They are treated as separate files.
5. Other raw converters may not support DNG very well.

Sizzlingbadger,

Thanks.

Do you know if it's possible to reverse the conversion process, that is DNG -> NEF? What if I did NEF -> DNG -> :whistling:?

Phil
 

PhilBurton

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