RAW vs DNG: What’s the Difference and Why Does it Matter?

By: Simon Ringsmuth

As a photographer, you have no doubt heard people talk about file formats, specifically RAW and JPG. Some people shoot only in RAW, others like JPG, and many photographers use both. Each format has benefits and drawbacks, but if you want the most amount of control over your pictures, you probably shoot in RAW. However, there is a third option you might not even know about: Digital Negative, or DNG. With this other format in the mix, the issue isn’t so much RAW vs JPG, but RAW vs DNG.

DNGs can speed up your Lightroom workflow, but there are some tradeoffs to be aware of.

Understanding RAW

RAW files, unlike JPG files, store all of the light and color data used to capture an image. That means you can recapture blown-out highlights, make better white balance corrections, and have a great deal of editing freedom you don’t get with JPG.
Nikon, Canon, Sony, and others all let photographers shoot in RAW, but each of their RAW files is different. For example, the file extension for a Nikon RAW file is NEF, Canon is CRW, and Sony uses ARW.
As a result of this, cameras from these manufacturers process and store RAW data a little differently. Third-party editing software has to interpolate and reverse-engineer the method used to create the RAW files.
This is great for camera makers because they can tweak their hardware and software to work really well with their own RAW formats. However, it’s not always the best for photographers and editors.

RAW and DNG files give you plenty of editing room that JPG does not offer. Nikon D500, 85mm, 

f/1.8, 1/4000 second, ISO 100

Digital Negative

Adobe developed the Digital Negative (DNG) format in 2004 as an open-source alternative to the proprietary RAW formats that most camera manufacturers used.
What Adobe did was essentially level the playing field by giving everyone access to the same format for working with RAW files.
DNG is open-source, which means anyone can use it without paying licensing fees. A few manufacturers like Pentax and Leica support DNG natively. However, for everyone else, there are easy ways to convert RAW files to DNG and get all the benefits of the latter without the hassles of the former.
DNG is particularly useful if you use Adobe products, like Lightroom and Photoshop, but other editing software support it too.

The photo information in each file is identical, but there might be some reasons to choose one over 

the other.

When looking at the RAW vs DNG issue, there are some important benefits as well as drawbacks that you might want to consider before you switch.
However, please don’t look at this as a matter of which format is better.
Neither RAW nor DNG is objectively superior; both have advantages and disadvantages. The point is to give you enough information to make an informed choice about which format works for you.

DNG benefits

1. Faster workflow

The main reason many people use DNG files is related to editing efficiency when using Lightroom. Since DNG and Lightroom are both made by Adobe, it stands to reason that they would work well together.
If you have ever found doing some simple operations with RAW files in Lightroom frustrating, like switching photos or zooming in to check focus, you will be shocked at how fast things like this are when using DNG files.
Switching from RAW to DNG has made a huge difference for me in speeding up my Lightroom workflow.

Nikon D750, 40mm, f/1.4, ISO 360, 1/180 second.

2. Smaller file sizes

File size is another area where DNG has an edge in the RAW vs DNG debate. Although, it might not be quite as important now with storage so cheap compared to ten or twenty years ago.
DNG files are typically about 20% smaller than a RAW file, which means you can store more of them on your computer. If you are limited in storage space, DNG just might be a good option for you.

I converted a folder of RAW files to DNG. Both contain the exact same data for each photo, but the 

DNGs are much smaller. The entire folder of RAW files is 1.75GB, whereas the folder of DNG files 

is 1.5GB.

3. Wide support

Because DNG doesn’t require a proprietary decoding algorithm, like RAW files from major manufacturers do, there is wider support from a variety of editing software. Various archival organizations, such as the Library of Congress, even use this format. That means it should work just fine for most photographers too. Personally, knowing this helped settle the RAW vs DNG debate for me, but you might prefer another solution.

4. Wide support

One additional benefit of DNG has to do with editing metadata and how it is stored. Lightroom is non-destructive, meaning that any changes you make to an image, you can alter at any point in the future. The original file remains untouched, and a record of your edits is stored separately.
When working with RAW files, these edits are written to a very small file called a sidecar. However, if you use DNG, all your edits are stored in the DNG file itself. Most people consider this an advantage since it requires fewer files to store and manage, but it can be a drawback which I explore later in this article.

Nikon D750, 40mm, f/1.4, ISO 1000, 1/3000 second

DNG Drawbacks

1. File conversion

Since most cameras don’t natively shoot in DNG format, you need to convert your RAW files if you want to use it.
Lightroom can do this automatically for you when importing, but it does come with a drawback that may be significant. Depending on the speed of your computer and the number of RAW files you import, the conversion to DNG can take anywhere from a few minutes to a few hours.
This could be problematic for some people in high-speed workflows such as sports and other action photography. Personally, I don’t mind. I just do the import/convert operation before dinner or at another time when I don’t need to start editing immediately.
I like to think of this initial conversion time as the culmination of all the seconds I used to spend waiting for RAW files to render, but all rolled into one lump sum. It’s a tradeoff I’m happy to make, but some people might find this a dealbreaker and stick with traditional RAW formats.

Converting lots of RAW files to DNG can take a great deal of time. And this is time that some 

photographers don’t have.

2. RAW metadata loss

Another drawback to the DNG format is that some of the RAW metadata gets lost during conversion. All the usual metadata you would expect is intact such as exposure, camera information, focal length, and more. But some information like GPS data, copyright information, and exact focus point don’t always transfer over.
Additionally, the built-in JPG preview gets discarded in favor of a smaller preview, which is another trick Adobe uses to bring down the size of DNG files.
Whether this information matters is up to you. Personally, I find none of the lost metadata a dealbreaker.

3. Multiple editors

One other issue you might want to consider is whether your workflow involves having multiple editors work on the same RAW file.
If that’s the case, then the lack of a sidecar file could be problematic. Essentially, the sidecar acts as a storage locker for all your edits. The RAW file is untouched, but the sidecar stores a record of your edits. This means that if you have two people working on the same RAW file, you can share your edits just by copying the sidecar files.

Edits to RAW images get stored as sidecar files. You can send these sidecar files to other editors to 

share your RAW edits (as long as they have the original RAW files).

If you use DNG, you have to share the entire DNG files, which can be problematic compared to the ease of copying a tiny sidecar file.
For most people, this probably won’t matter, but for those who work in editing rooms or production houses that rely on sidecar files to store edits, DNG might not be the best option.
Finally, if you research this issue long enough, you will hear some trepidation about the longevity of DNG since the biggest camera makers, like Canon, Nikon, and Sony, do not officially support it. Personally, I’m not too worried about this since DNG is a widely-adopted industry standard, and if it’s good enough for the Library of Congress, then it’s good enough for me.

How to use DNG

If you want to give DNG a try, you can start by converting some of your existing RAW files. In your Lightroom Library module, select the RAW files you want to convert and then choose Photo->Convert Photo to DNG.

I recommend checking the values you see here, though if you are ready to go all-in, you can also 

select the option to delete originals. The “Embed Fast Load Data” option is what really speeds things 

up in Lightroom.

Un-check the option to use lossy compression if you want to retain all the data from the RAW file instead of having Lightroom toss out some in favor of a smaller file size. Also, you don’t need to embed the RAW file since doing so will more than double the file size of your DNG.
Another option is to use the Copy as DNG setting when importing photos from your memory card. This will add a great deal of time during the import process since Lightroom converts every one of your RAW files to DNG.
However, for me, the tradeoff is worth it since DNGs are so much faster to work with in Lightroom compared to traditional RAW files.

As with many aspects of photography, the answer here isn’t black and white, and there is not a one-size-fits-all solution. The question of RAW vs DNG isn’t about which format is better, but which format suits your needs.
There is no data loss when working with DNGs, but there are some issues compared to RAW files, and it’s important that you make an informed choice.
If you have experience working with DNG files and would like to share your thoughts, I would love to have them in the comments below!

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