Feb 162012
 

In Lightroom’s Import dialog (and in the Library module), you are given the choice to convert your camera manufacturer-proprietary raw files into Adobe’s raw file format, DNG.

Adobe Copy as DNG Lightroom

 

I have gone back and forth on recommending conversion to my students, and in my own workflow  — not because I don’t trust Adobe’s conversion, but because I just have never seen it as mission-critical.  While I could see some advantages, they just haven’t been that compelling to me, and converting to DNG does make the Import process take a lot longer.  (At this point I do convert, but I don’t feel strongly about it.)

Though still not mission-critical, Lightroom 4 is introducing some new advantages, to make Lightroom performance faster with DNG’s than with proprietary raw files, and to allow lossy compression.

Here is a great article from C-Net: Adobe Offering New Reasons to Get DNG Religion, on  what’s new, and on the advantages and shortcomings of DNG.

Do you convert now? Will you with Lightroom 4? Do comment with any thoughts.

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  28 Responses to “To DNG or Not to DNG”

  1. I’ve always been a proponent of DNG conversion. The most important reason for this is that in most cases it is going to save quite a bit of space on your storage device, even when saving as lossless-DNG (the idea of using lossy-DNG gives me the heeby jeebies). I haven’t checked in a while but if I remember correctly I save around 10% on, for instance, Nikon-NEF->lossless-DNG conversion. That’s a lot of space once you take into account the 20k images that I have on disk.

    It’s also nice to have all of my RAW files from various cameras and manufacturers in a single format on disk.

    Finally, I’m a software developer and the idea that the DNG format is open is appealing to me. If I ever want to do something interesting with those image files I’ll be able to write an app that can access that data. Not so with proprietary RAW formats.

  2. I always convert to DNG. Sometimes I convert on import; other times I import the CR2 files and convert later. It depends on if I need to do edits right away or if I’m just starting the import and moving on to something else (like bed, or drinking, or whatever).

    I will never, however, engage in lossy compression in what is supposed to be a RAW format. That’s just WRONG!!!! :) A new religion is now started. When I want to lose information, I’ll export to JPG.

    ciao

  3. I convert. Because that’s how I saw Terry White do it when I was first learning LR. So I do. I see no reason to stop.

  4. I convert my RAW files to DNG but not at import. I import my photos and once I have gone through and deleted those I do not want to keep, I convert the remaining files to DNG. The reasons I convert are that I save space (DNG files are smaller than Canon’s CR2 files) and the changes I make in Lightroom can be saved to the DNG files. If you make changes on a CR2 file, Lightroom creates a separate XMP file to store the edits. I prefer to have everything in one smaller file in case that extra file were to get lost or deleted. And finally, the only reason I don’t do the conversion on import is that it would take extra time to convert the files I’m going to delete right away anyway, so I wait until after the first pass through them. (I delete a lot of files)

    • Chris, what is the mechanism within Lightroom that allows you to convert to DNG after Import? IIf I decide to switch to DNG, I will want to go back and convert my “old” files to DNG as well but I haven’t determined how to perform that conversion post-import.

      • David, you can select the files and then in the menu bar, go to Library>Convert Photos to DNG.

        Laura

  5. Oddly enough, I used to convert and stopped specifically because I wanted the XMP file separate. Specifically, I use an online backup service (in addition to two local copies) and every time I make a change to a keyword or rating it would have to upload the whole DNG all over again.

    • It’s seems a very good reason.
      As of today, there are no reasons enough to me about this issue for converting or not. Another reason for not to do it is that some information that includes the CR2 files that uses my Canon camera are not included in the DNG file (e.g.: focus point)

    • Check to make sure your backup service does a block level backup and not a file level backup. If it’s block level backup it would only have to send the part of the file that changed. Since a keyword, rating or any metadata changes would be very small you’d only essentially be updating a data amount similar to an xmp file.

      Also, if you’re backing up your lightroom database and not sending metadata changes to file this wouldn’t be a concern either since changes in lightroom don’t alter the file. I don’t care if changes don’t make it to an xmp file or a dng file since I don’t edit outside of lightroom or share DNG with any other application.

  6. I always convert to DNG on import. The .xmp data is embedded within the .dng and not stored as a separate .xmp sidecar file. I like the idea of just having to manage and keep track of a single DNG file rather than two files- one proprietary RAW and its associated .xmp.

    It probably makes little difference to ongoing LR performance but it seems a more efficient and logical system to me.

  7. Like most of the above, I import into Lightroom as .dng. Makes different cameras the same and is very simple (that’s me). Never lossy .. what would be the purpose of RAW??

    Also, Scott Kelby recommended it and I’m a disciple of his as well as yours. :-)

    Looking forward to your LR 4 manual. Any chance it could also be an eBook for iPad??

    • One advantage of the dng format is the renaming of files.

      If some program (other than lightroom) renames your files, the xmp files that are associated with the renamed files might not be renamed properly, and you might end up losing your edited work.

      I don’t use dng files yet, as I am not sure how universally this format has been accepted by other software manufacturers.

  8. I let Lightroom manage my CR2 files but I tend to export finished work as DNG and JPG. I don’t like the idea of converting my source files from CR2 to DNG because I worry about losing metadata in the image. I’m totally confident that the DNG will store the raw image data without any loss, but I’m always concerned that the conversion process will lose extra information from the camera that isn’t supported yet.

    I’m umming and ahhhing now though, because handling CR2 files is definitely slower than DNGs, but Rob Rogers makes a good point about uploading XMP files separately.

  9. I convert all my NEF files to DNG before I import into Lightroom. I use Imageingester Pro to import, rename, convert to DNG, and make a backup copy of the raw NEF from my SD card. Then I do an add in LR to import the DNG files to LR. I use adobe color space when shooting. I make all my adjustments in LR. So at this point I have a DNG file that looks great on my PC screen. I can print it or upload it to my website as is. My question is should I be converting to jpg and/or sRGB color space before I print or post to web?

    • Hi John, why do you use Imageingester rather than LR to convert and rename your files — is it faster? When you shoot in raw, the color space set in-camera is ignored, so technically you are not shooting in Adobe RGB, you’re shooting in the color space of your camera, which may be closer to ProPhoto. When you upload to the web, yes, convert to sRGB. If you are doing your own printing, I’d suggest printing with profiles (and not converting to sRGB as an intermediate step.) If you are sending photos to a lab to print, if they have a profile, I would convert to that; otherwise use whatever color space they recommend — all will take sRGB, some can handle Adobe RGB.

  10. A quick question on NEF and DNG.
    I usually use DNG files, but I was covering a music festival and for the sake of speed and being able to use a few for social media I left my files as NEF.

    Now that I’m back home I was thinking of converting them all to DNG using lightroom 4,
    My question Will I loose my changes to the NEFs I processed already using lightroom if I convert them now to DNG?

    Thanks for any insight!

  11. If you import your Raw ( or have converted your images from before) photos and copy to DNG, do you then delete the NEF file? I was checking my Finder and there are NEF, DNG, and Jpg files for way too many pictures which must be there because I changed them after the fact (?) ?

    • Hi Carol, if you converted to DNG from within the Library module in Lightroom by going to Library>Convert Photo to DNG, there is a checkbox to delete the originals after successful conversion. I personally do delete the originals. Some people choose to keep the originals, in case there are any issues with the DNG down the road.

  12. Hi

    I’m using Adobe DNG converter when converting my NEF’s to DNG. But then I notice when opening DNG’s in CS4, they look different than how I captured them. For example, colors are either less/more vibrant and slightly brighter/darker than it was.

    Is this suppose to be normal? I work hard in capturing my pictures when shooting in manual. I know I can just edit them to match them as close as possible but I’d like to maintain the settings I captured with.

  13. To DNG or not, that’s indeed the question. For years I’ve been working with the Canon RAW files from both my cameras and was quite happy this way. Bought a medium format now with an 80mp back which gave me some headache to begin with as Lightroom and Photoshop didn’t support the new RAW format yet. Took a few weeks but not that’s sorted. Looking and reorganising all my files now I started to use DNG and keep the RAW only as a backup but this is where I finally realise that DNG doesn’t necessarily mean you save space.
    My 80mb RAW files as dng turn out to be between 100 and 160mb!

  14. I’ve been doing some tests in order to understand if DNG conversion really affects image quality or not.
    After converting a few NEF images (some originally overexposed and some underexposed) I opened both NEF and DNG images in Camera Raw and processed the files.
    The results were quite unexpected.

    If I save NEF to DNG without compression the images take an average of 10% less space. I wasn’t able to see any visible diference between the two images. But what excited me the most is the fact that the conversion of the full resolution NEF to compressed (lossy) DNG files takes up only 25% storage space compared to NEF RAW. Ex. NEF file takes 40MB of storage and the compressed DNG takes up 10MB!

    But how about quality of the compressed DNG files?
    I was blown away with the amount of detail that a compressed DNG file can save. I have a lot of difficulty in finding differences between an original processed NEF file a a processed DNG file. I may even add that the only difference i was able to verify is a little bit of colour loss in the shadows of the DNG file.
    My conclusion is that compressed DNG has the best ratio between quality/size i’ve seen so far.
    No doubt this is a very good alternative to save space while keeping a very good quality image.

    For those in doubt, always keep the originals.

    • Thanks for sharing your test results and impressions, Nuno! This is very helpful. For most photos I personally would choose to keep the originals and not compress, but for things like snapshots and frames for timelapse videos, I could definitely see compressing.

  15. Hi All!
    Just throwing in my two cents … I have many thousands of images, most RAW Canon (.CR2), but also have a Panasonic Micro Four Thirds that produces .RW2 RAWs.
    I’ve been pondering the whole DNG issue for a year, and will probably burn off my originals on Blu-Ray, and also Archive on two External drives (you can NEVER have too many backups!! LOL!), then convert to DNG.
    One thing that stood out for me was a quote from a Mosaic article that said:
    “Embedded file verification –
    The DNG format includes a checksum that can detect file corruption. With regular RAW files it can be impossible to detect file corruption. This is a pretty important archival feature for an image format to have.”
    Uhhh, YEAH!

    In another Laura Shoe Article on RAW + JPG or just RAW (Thanks Laura! You ROCK! ;-) ), a commenter was concerned about data corruption. Having that extra level of security while transferring during Import gives us another reason to slide towards DNG. Personally, I’ll backup my originals, just in case …

    Side note: Having been a Computer Tech for 34 Years, I know how absolutely WRONG things can go in just a moment on a computer. One power glitch, even with a UPS, and you can be toast.
    Question – How many of you carefully power protect your PC, but plug your phones, tablets and laptops directly into a power outlet to charge?
    Thought so.
    Are you MAD? (LOL!) Might want to reconsider a travel UPS. It won’t stop it all, but …
    Rule: Backups are important, but they often fail without you realizing until you need them, to discover in your hour of need that they’re 6 months out of date.
    You like your Pics? Backup redundantly, there’s NO excuse to spend thousands on your photo gear and cheap out on getting two backups. Oh- and spend some $$. The cheap ones are just that. Cheap. Trust me, I’m a factory trained Hard Drive repair tech.
    ~Sorry to steal the thread, Laura! ~ {Grin}
    All The Best, PuterPro

    • OOPS! EDIT –
      “Might want to reconsider a travel UPS”
      I meant to say a Travel Surge protector … (like for a laptop, 1 to 3 outlets, portable, check Amazon or your fav electronics store…
      PuterPro

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