Lightroom: To DNG or not to DNG, that is the question.

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  • Updated 6 years ago
Is there a performance benefit to changing all of my proprietary Raw files over to DNG on import? I'm wondering if Lightroom (which has gotten slow since 4.1) will speed up at all if I use Adobe's format.

Along the same lines — is this common practice that everyone follows? Or are there any concerns or issues I should be aware of?
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Joseph Rivera

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  • undecided

Posted 7 years ago

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Rob Cole

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I don't DNG, because I want to be able to open my files in manufacturer software too (or other software which does not support *converted* DNGs), but lots of people do DNG, and they have their reasons...

I don't think you will notice much performance difference, but why don't you try a few and report back?
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Paul Trotter

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The benefit of dng files lies in the fact that they have smaller file sizes than raw files and that Adobe has committed to always supporting the file type. Raw files are native to the specific camera you are using, which could result in you not being able to open an old file because camera raw does not support your particular file. For example, Canon raw files are labelled cr2, but these files vary according to the model of camera.
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Chris Packrat

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DNG will save you a few bytes on your hard disk compared to many raw formats, and will embed forever in your files dozens of useless color profiles that you once may have had the idea to apply to your digital negatives. All for free :)
However it could also discard useful proprietary information ("don't understand that metadata? trash it!"), and will be a hog for your backups compared to Raw + sidecar Xmp file (edited one typo in metadata or some develop settings for thousands of DNGs? let's re-backup some terabytes weekly...)

And given how Adobe stopped publishing its revisions and additions to the DNG specification a while ago, you cannot get sure how the format will really evolve... (Never trust a commitment, promise or lie by any software vendor. Trust published specs and legible source code.)
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Clint Steed

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With a Nikon D800 I converted Nikon Raw files (NEF) to DNG on import to LR 4.1.

I found the DNG files take anywhere from just a little bit to twice as long to load the 100% previews than the NEF files. I increasded my Raw cache to 50GB and the load times signifcantly reduced.

I get about a 20% in file size, however the embrded preview file for OS viewing is very small. While this effects the OS preview or Picture Viewer it does not effect FastPictureViewer.

I was hoping that LR adjustments would be saved in the DNG files, but that has to be done manually.

When exporting DNG files they do not preview on my Win 7 computer at all. Still researching this.
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Rob Cole

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There is something wrong with having D800 files in DNG, or something.

I had previously done brief performance tests using D800 (NEFs) and found rendering to be about double that of D300 (which seemed about right). However I'm working now with D800 files as DNG and they take anywhere from a half minute to a minute (or more) to load preview in lib (yeah, like order of magnitude more than they should), time to render in dev module is same as previously experienced, but file is forever being reloaded for dev, even when it should be in ram cache (e.g. switching back and forth between two loaded D800 DNGs in dev module).