A DNG file is an alternative to the many different versions of raw files offered by the many different camera manufacturers. The name, DNG, is shorthand for – Digital Negative.
It was developed by Adobe and is therefore compatible with all of their software applications. Adobe developed it to overcome the problems posed by having so many different formats of the raw file. Each camera manufacturer has their own version of raw files, and this makes it very difficult for software to keep up. As soon as a new camera is released, it can be impossible for some software packages to read the new raw files until an update is written and published. The DNG file is a way of overcoming these incompatibility issues.
Although Adobe invented the DNG file, they offer it as public domain software, and it is being handed over to the ISO (International Standards Organisation). Some camera manufacturers do shoot the DNG file as their native raw file: Pentax; Ricoh; Casio; Leica; Samsung and Hasselblad are some examples. However, even if your camera does not offer the ability to shoot DNG natively, you can still convert a raw file to a DNG file within some Adobe applications. Lightroom and Adobe Bridge offer the ability to batch convert many raw files at once, and for those who do not own Lightroom or Bridge, Adobe provides a free download of their DNG batch converter. The Adobe DNG Converter is a free application that allows you to convert raw files to DNG files with ease, even if it can be a slow process. A good excuse for a coffee while the conversion takes place.
A DNG file contains all the original raw file’s data. There is a lot of argument about how well the original raw data is copied over, but I have never noticed anything missing nor have I ever noticed any degradation in quality. So why bother?
Advantages of the DNG file format.
This is a list of some, but not all, of the advantages of converting raw files to DNG files.
- Longevity – I do not doubt that we will all be able to process our existing raw files for the next few years with current software. But, what happens when things move on so much that those raw files are too old to be supported by future versions of software packages? This is where the DNG file comes in. The DNG format is open source and will be developed well into the future. The Kodak raw file format is no longer supported by any application and should serve as a warning.
- Portability – The DNG file contains all the information about the file, including adjustments. There is no need to find and include the sidecar xmp file when you are sharing your raw files. This makes converting to a DNG file extremely useful if you are handing your file off for retouching.
- Output speed – Most software packages will be able to output faster from a DNG file than a raw file because all the information is embedded in the file and doesn’t need as much decoding.
- File size – A DNG file is smaller than the original raw file. For example, my Sony a7R ii shoots raw files that are around 80MB, but when converted to DNG, they reduce to approximately 45 – 50MB. They are still huge, but that’s over 30MB saving on every single file without a loss in quality.
- Corrupt files – A DNG file contains a checksum validation feature. This checksum feature can check the integrity of your DNG files. I am not sure what the technicalities of this are, but it’s reassuring to know that it is there. You can read more about this on Julieanne Kost’s Blog where she explains it far better than I ever could.
Disadvantages of the DNG file format.
- Time – As I mentioned above, it can take a long time to convert your raw images to DNGs, especially if your raw files are enormous.
- Compatibility – This almost sounds like a contradiction to the first advantage I mentioned above, but some software packages do not support editing of DNG files. Notably, it is the camera manufacturers’ own software that does not have support for DNGs – Nikon’s Capture NX is one example.
- Backing up metadata – All the adjustments you make to DNG files are written into the file itself. This means that when you save the DNG files, you are forced to copy a complete DNG file rather than just the sidecar xmp data that accompanies raw files. However, if you use Lightroom, you can leave all those changes to be managed by Lightroom without the need to continually save the files. This is my preferred workflow.
DNG File Scare Stories.
- Quality – There are still a lot of photographers who will insist that the conversion process reduces the quality of the raw file. When you open a raw file in Adobe Camera Raw (ACR) in either Lightroom or Photoshop, the ACR software internally converts the file to a DNG for processing, regardless of the format. Therefore, opening a raw file or a DNG file inside ACR will make no difference to the quality of the photograph.
- Adobe Standard profile – Despite what a lot of people think, converting to DNG does not change the colour profile to Adobe Standard. Instead, the conversion process adds a new profile of Adobe Standard to the list offered by the camera manufacturer. This profile is created by Adobe and is aligned to the Camera Standard profile of each camera manufacturer. You can change this using the Camera Calibration tab in Lightroom or ACR. It’s also straightforward to set a new default calibration profile for each camera you have. Contact me if you want to know how to change the default Profile. I’ll also put a post up for this too.
- DNG files only work in Adobe software – This is not true. Any third party raw processing application can read and edit DNG files. If you edit in Lightroom or Photoshop, you will probably need to save the DNG file to have the edits show up in another application.
Before I decided to convert all my raw files to DNG files, I researched the subject and was initially put off by some of the scare stories on the internet. However, I did read a lot of information that convinced me it was a good way forward. My collection of images was multiplying on my computer, and the file sizes were increasing with every new camera, so I needed a way to speed up my editing while reducing the file sizes.
All the positive information I read came from reputable sources, like Adobe and good blog sites, so I decided to go for it.
I convert all my raw files to DNG now and enjoy the benefits of compatibility, size and the ease with which files can be handed to me for retouching.
So, if you are considering converting raw files to DNG file format, just do it!