Converting to DNG during import
I’m going to assume that you know how to import images into Lightroom for this part. This is the most efficient way to convert Raw files to DNG but you need to be fully committed to the benefits of the DNG format because you will not have the original Raw files stored on your computer.
Along the top of the Import screen, you will see two copy options; Copy and Copy As DNG. Click on Copy As DNG to have Lightroom copy the files to your computer and convert them to DNG. As Lightroom copies the camera Raw files from the memory card, it places them on your computer before converting them all to DNG. You do not need to do anything more. It does take a lot longer to complete the import and conversion process but that simply means you can have another coffee.
Ah, but what about the options? The options discussed above. How do you set these? Well, these options are set in the Preferences and are used for all import conversions. To access the options in the Preferences, choose Edit > Preferences (Windows) or Lightroom > Preferences (Mac OS) then click on the File Handling tab. At the top of the File Handling tab, you will see the same options as discussed earlier. Set the options you wish and forget about them for future import conversions. Now you see why I structured this article to be back-to-front.
Adobe’s lossy DNG compression reduces the bitdepth to 8 bits. That’s another reason quality suffers when using this option. I never use it.
There is another utility called Slimraw (see here: http://www.slimraw.com/) which is much faster than Adobe’s DNG converter and also has better lossless compression — it consistently produces smaller files. It is a DNG to DNG compressor, so I first convert the raw photos to DNG, then pass them through Slimraw. It also has an interesting 10-bit compression mode where the DNG pixels are transformed logarithmically before the lossless compression. This shaves off more of the size, without any observed quality loss when processing.
Dean,
Thanks for your reply. I will definitely give that a look. Thanks for the info.
Martin
Why do you need DNG files, when would you use them ?
Gordon,
There are a few advantages to DNG files over the manufacturers’ raw files. A DNG file is significantly smaller than the raw file from your camera. Not smaller in terms of dimension but smaller in terms of hard drive space. My Sony a7Rii files are about 80 MB in their native ARW raw format but when converted to DNG, they are about 43 MB. That adds up over several thousand files. Also, DNG files have the adjustments that you make stored inside the file. Raw files rely on a separate XMP file. This XMP file can be easily forgotten if you choose to move your images to another location or another drive. Losing the XMP file will mean that all your edits will be lost too. Plus, I find that the DNG files load quicker and are more responsive inside Lightroom.
Converting to DNG is not necessary nor is it even an advantage to everyone but I also want to reassure people that it is not going to be a disadvantage nor is it as scary as some of the internet stories suggest.
Have a read at this article I wrote a while back regarding the nature of DNG files and let me know what you think.
Ive got Lightroom 6 and I am still unable to Import, as the preview window says “Preview Unavailable for this File?”
Are the Raw files converted to DNG? It is these converted DNGs that you need to import.
I downloaded DNG converter but when I open my Lightroom 5 I cannot view NEF files anyway, like John Forshaw above I cannot preview the files
Did you convert the NEF files to DNG using the converter?
I converted thousands of raw files to dng but made the mistake of not checking the ‘Delete originals after successful conversion’ option. What’s the best way to remedy this and save space?
Rob,
Using Lightroom Classic, open the folders where your original Raw files are still stored. Sort the images in the folder by file type, select all the Raw files and delete them.
Martin.