Should you use DNG or RAW format? This is one of the most important questions that you as a photographer need to ask yourself, because it will definitely affect your digital photography workflow. Every photographer has their own say on whether to use DNG or RAW, but it is important to know the key differences between the two, along with their advantages and disadvantages. In this article, I will provide as much information as I can about both formats, in addition to my opinion and workflow. If you are looking for more information about how RAW images compare to JPEG images, then please read my “RAW vs JPEG” article.
RAW images, also known as “digital negatives” are truly “raw”, meaning they are almost unprocessed data coming directly from the camera sensor. Unlike JPEG files that can be easily opened, viewed and printed by most image-viewing/editing programs, RAW is a proprietary format that is tied to the camera manufacturer and sensor, and therefore is not supported by all software products. RAW files preserve the most amount of information about an image and generally contain more colors and dynamic range than other formats.
1.1) Advantages of RAW format
- RAW files contain full JPEG Previews that were processed by the camera, using the camera settings you chose when you shot the image.
- In addition to basic exposure information, RAW files also store other camera-specific data such as focus point, picture controls, etc.
- RAW files are fully supported by their manufacturers and therefore work with camera-specific software packages such as Nikon Capture NX.
1.2) Disadvantages of RAW format
- Not all software packages can open RAW files. If you have a brand new camera that just got released, you might need to wait for a while for software companies to catch up and update their software so that your RAW files could be opened and worked on, even on the most popular image-editing products such as Lightroom.
- Because RAW files cannot be modified by third party software, your settings will have to be stored in a separate sidecar (XMP) file, which means more storage and tougher file management.
DNG is also considered to be a RAW image file. It is Adobe’s proprietary image standard that was created to store image data in a generic, highly-compatible format, unlike RAW files that have specific formats based on manufacturer and camera type. Although DNG was invented by Adobe and is supported in all Adobe applications, there are other companies like Leica and Hasselblad that adopted this standard and use it in their cameras as their native RAW file format.
2.1) What are the advantages of DNG format?
- No need to be worried about proprietary camera RAW formats – once a RAW file in converted to DNG, it will work with any software that can read the DNG format.
- DNG files are generally smaller than RAW files and can be made even smaller if minimal or no JPEG Preview is stored within the file.
- Changes to images can be written directly into DNG files without having to create separate sidecar XMP files to store this data. This simplifies file management.
- DNG files are capable of storing full original RAW files and these RAW files can be later be manually extracted, if needed.
- Adobe provides many ways to automatically convert RAW images to DNG format in such programs as Lightroom.
- Unlike RAW files, the DNG format includes checksum information in the file to detect and prevent file corruption.
- Adobe continues to work on the DNG format, enhancing it year after year and adding more functionality and features.
2.1) What are the disadvantages of DNG format?
- Conversion from RAW to DNG takes extra time during the import process.
- DNG does not work with all manufacturer image-processing programs. For example, it doesn’t work with Nikon’s Capture NX product.
- DNG strips out some of the unrecognized meta data (such as Active D-Lighting and Picture Control) from RAW files, making it impossible to retrieve this data from DNG in the future.
- Because all changes are written into the DNG file, you would have to back up the entire DNG file every time you make changes to it.
3) Should you use DNG or RAW?
I personally prefer to use DNG for the following three reasons:
- Compatibility – it doesn’t matter what camera I use today or tomorrow, my files are preserved in one highly-compatible format that is here to stay.
- Simplicity – all changes are written into the same file and I do not have to worry about having one separate file per image just to store my post-processing settings.
- Size – that 15-20% of extra space does make a difference when you have tens of thousands of pictures. Why should I waste space by storing information in RAW files that I do not need?
Sure, it does take more processing power and time to work with DNG images compared to RAW, but the above advantages far outweigh the problems with RAW for me. I do not use Capture NX and within the last two years, I haven’t had a need to go back to my original RAW files. My backup process is actually simpler and smoother now, because I do not have to worry about selecting only sidecar files for backup – I just backup whatever photos I work on.
As far as whether to preserve or not to preserve the original RAW/NEF files, I personally keep my RAW files until I back up my photos to at least two separate hard drives. Once I am absolutely positive that everything is fully backed up, only then do I purge my old NEF files to save some space.
Please let me know if you have any questions or feedback in the comments section below.