# RAW vs DNG



## Fab_Angilletta (Feb 1, 2012)

I shoot RAW+JPEG (small) and I make a backup of all my RAW files. I recently found out about the DNG format. I observe around 20% smaller files (when RAW is converted to DNG). So this means I can store 20% more files in my backup disk.

So my question is: Is there a downside of using DNG instead of RAW?


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## ghosh9691 (Feb 1, 2012)

Fab_Angilletta said:


> I shoot RAW+JPEG (small) and I make a backup of all my RAW files. I recently found out about the DNG format. I observe around 20% smaller files (when RAW is converted to DNG). So this means I can store 20% more files in my backup disk.
> 
> So my question is: Is there a downside of using DNG instead of RAW?



Not that I have noticed! I use DNG exclusively and store all my RAW files in that format. When I import the files over from my camera, I have Lightroom set to automatically convert it to a DNG file. The advantages of using DNG are many...but primary advantage is that almost all software can read and handle the DNG files. It is not proprietary like the Canon or Nikon RAW formats.


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## Orangutan (Feb 1, 2012)

I believe DNG is a raw format, it is simply an alternative to CR2 and Nikon's NEF, etc.

http://en.wikipedia.org/wiki/Digital_Negative

Only possible downside is that certain software (e.g. Canon-specific software) may not know how to use DNG.

20%space savings is not significant. I'm hoping DNG (or something similar) will become standard across the industry, and across vendors. Not holding my breath, though.


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## K-amps (Feb 1, 2012)

Fab_Angilletta said:


> I shoot RAW+JPEG (small) and I make a backup of all my RAW files. I recently found out about the DNG format. I observe around 20% smaller files (when RAW is converted to DNG). So this means I can store 20% more files in my backup disk.
> 
> So my question is: Is there a downside of using DNG instead of RAW?



A nice read here: http://mansurovs.com/dng-vs-raw 

Also Adobe relevant info: http://lightroomkillertips.com/2010/to-dng-or-not-to-dng/

I use LR3 and convert all my RAW's to DNG. DNG's behave much like RAW's in terms of how much you can manipulate exposure/ color balace etc without overdoing it. I cannot apply the same levels in jpeg and get away with it.


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## EYEONE (Feb 1, 2012)

ghosh9691 said:


> When I import the files over from my camera, I have Lightroom set to automatically convert it to a DNG file.



No kidding? I didn't know you could do that. I've wondered about DNG for a while thinking it might be safer than CR2 for longevity. I wish cameras would shoot in DNG but this might work just as well.

Thanks for the info!


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## K-amps (Feb 1, 2012)

EYEONE said:


> ghosh9691 said:
> 
> 
> > When I import the files over from my camera, I have Lightroom set to automatically convert it to a DNG file.
> ...



In my case LR3 just did it, I am not even sure if it asked me ???


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## aldvan (Feb 1, 2012)

A difference in file dimensions means always a loss of information, unless the larger file is wasting space, and this is not the case for RAW format. Compression is not a pyisical proces, but a logical one. Some information will be necessary discarded in the process. May be the discarded bytes were, on a perception physiology basis, not very relevant, but since the cost of memory space is more and more decreasing, I prefer to keep the pure, simple and tautological RAW format...


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## unruled (Feb 1, 2012)

I thought dng was a lossless compression... hence digital negative. not all compression loses quality- think zip files or flac.


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## corpusrex (Feb 1, 2012)

K-amps said:


> EYEONE said:
> 
> 
> > ghosh9691 said:
> ...



When you import photos in LR3 there is an option at the top of the import window that asks if you want to "Copy as DNG" "Copy", "Move" or "Add".

To change the DNG import settings go to the "Preferences" and chose the "File Handling" tab. At the top is the options for the DNG import like, Extension, Compatibility and Jpeg preview size etc.

Hope that helps or alternatively if you already knew all this... disregard.


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## photophreek (Feb 2, 2012)

From my understanding of the differences between DNG and the RAW CR2 is that changes or edits made with LR are stored in a separate XMP sidecar file which also holds the metadata information for the RAW file. As a result, for each RAW file there are two files, the RAW file itself and the XMP sidecar. The DNG format will include the sidecar information with the RAW file in one file.

Adobe is probably hoping that the industry will standardize the RAW file format to DNG so they don't have to make changes/updates to their software when camera manufactures make changes to their RAW file formats.


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## ghosh9691 (Feb 2, 2012)

EYEONE said:


> ghosh9691 said:
> 
> 
> > When I import the files over from my camera, I have Lightroom set to automatically convert it to a DNG file.
> ...



There are four options on import: Copy as DNG, Copy, Move and Add. Select "Copy as DNG" and LR will automatically convert RAW files (and some JPEGS) to DNG format.


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## ghosh9691 (Feb 2, 2012)

aldvan said:


> A difference in file dimensions means always a loss of information, unless the larger file is wasting space, and this is not the case for RAW format. Compression is not a pyisical proces, but a logical one. Some information will be necessary discarded in the process. May be the discarded bytes were, on a perception physiology basis, not very relevant, but since the cost of memory space is more and more decreasing, I prefer to keep the pure, simple and tautological RAW format...



AFAIK, conversion to DNG does not result in a loss of data and neither is DNG a lossy format. In fact, some cameras, notably Leica M9 and S2 use it as native format instead of proprietary RAW files.


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## gbchriste (Feb 2, 2012)

photophreek said:


> From my understanding of the differences between DNG and the RAW CR2 is that changes or edits made with LR are stored in a separate XMP sidecar file which also holds the metadata information for the RAW file. As a result, for each RAW file there are two files, the RAW file itself and the XMP sidecar. The DNG format will include the sidecar information with the RAW file in one file.
> 
> Adobe is probably hoping that the industry will standardize the RAW file format to DNG so they don't have to make changes/updates to their software when camera manufactures make changes to their RAW file formats.



Only partially correct. Using the sidecar file to store LR edits is an option but that is not the primary and most common method that LR uses to store edits. The standard configuration is to use a LR catalog. The catalog is essentially a database file that contains the thumbnail views and all edits applied to the images you are managing with LR. Unlike the sidecar files, for which there is one for every image, one active LR catalog file may contain edit information for hundreds, maybe even thousands of LR images. You can create new catalogs and switch between them and shooting pros with lots of images will usually create separate catalogs perhaps for different clients, or new catalog over period of time, etc etc.

LR includes utilities for managing the catalog - backup, import, export etc.

The XMP sidecar file is how Adobe Bridge handles edits and the incorporation of XMP support lets you bring in images to LR that were previously edited in Bridge with those edits intact. You can also create XMP files for images that are managed by a LR catalog so you take those images out of LR in to Bridge and have the LR edits intact in Bridge.


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## photophreek (Feb 2, 2012)

gbchristie wrote:


> Only partially correct. Using the sidecar file to store LR edits is an option but that is not the primary and most common method that LR uses to store edits.



I understand and completely agree with what catalogs are as I have had a catalog corrupted and all my photos in the catolog would not open. Luckily, I had a backup and could restore the catalog and my work and not that silly backup that Adobe makes you do when you close LR because that was also corrupted. If you sent one of your RAW images without the XMP sidecar file, the recipient would not be able to see any edits you had done in LR and only see the original RAW image without the metadata. 

The DNG does away with needing both files and makes sharing and transfering files easier. I'm not sure what happens during the conversion to DNG at import into LR and as a result, I did not let LR convert my RAW images to DNG. As another responder stated and I agree, until I have an idea what Adobe is doing with the files to make the DNG smaller, I'm sticking with the original RAW file format.


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## Edwin Herdman (Feb 4, 2012)

DNG trades one proprietary standard for another. Like the "Adobe RGB over sRGB" debate, it seems like another way to hobble performance so you can bind yourself more tightly to Adobe products (which I don't use anymore).


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## pdirestajr (Feb 4, 2012)

One difference I notice is that the DNG file doesn't preserve a few of the Canon specific details- like showing where focus points were used. Besides that, I don't notice much of a difference.


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## TexPhoto (Feb 4, 2012)

Who wants to wear t-shirts that say "I shoot DNG"?, or" DNG to the Core"? Seriously, it does not have the sex appeal of RAW.


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## Bruce Photography (Feb 4, 2012)

pdirestajr said:


> One difference I notice is that the DNG file doesn't preserve a few of the Canon specific details- like showing where focus points were used. Besides that, I don't notice much of a difference.



Good note. For now that is the reason I stay with CR2 until DNG has all the meta info that is inside a CR2. Even though focus point isn't really that great to know, at least it helps to know which point you started with.


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## K-amps (Feb 4, 2012)

TexPhoto said:


> Who wants to wear t-shirts that say "I shoot DNG"?, or" DNG to the Core"? Seriously, it does not have the sex appeal of RAW.



We all "shoot" RAW


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## Mt Spokane Photography (Feb 4, 2012)

pdirestajr said:


> One difference I notice is that the DNG file doesn't preserve a few of the Canon specific details- like showing where focus points were used. Besides that, I don't notice much of a difference.



There are now THREE flavors of DNG. 

One which embeds the entire RAW file in it with all the raw information in addition to the edit info.

One which embeds only the edited image(This is the one most are discussing here)

One which embeds the edited image with lossy compression, but not as much as jpeg. It might be better than saving jpegs? Its new and can be tested in Lightroom 4.

You can take your choice.


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