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Author Topic: Problems after importing DNG's into Lightroom  (Read 1359 times)

LawrenceBraunstein

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Problems after importing DNG's into Lightroom
« on: March 01, 2014, 03:46:44 pm »

I recently purchased the new Sigma 24-105mm f4 ‘art’ lens for my Nikon D800E (the Nikon F mount version just began shipping here in Germany). Lightroom has, as yet, no lens profile for this lens. However, several days ago Adobe released their latest ACR update (version 8.4 RC) which, among other things, includes a lens profile for the Sigma lens. Until Lightroom releases their next update which, I assume, will also include the new Sigma lens profile, I thought a possible workaround could be as follows: import into LR (default procedure), open the photos in ACR (via Bridge), apply the lens profile, and then save the files back to their original folder as 16-bit DNG’s (ProPhoto RGB working space). Then all I would need to do is synchronize the folder in LR and import the new DNG’s. The problem is, it’s not working! Though the profiles are definitely being applied in ACR, after importing the DNG’s back into LR, they remain unaltered (no profile applied!). However, if I save those same photos in ACR as 16-bit TIFF’s, the lens profiles survive the re-import into LR perfectly! Obviously, there is something concerning DNG’s and their relationship to ACR and LR which I unfortunately do not understand! What’s happening here? I’d really appreciate help with this.  If possible, I would infinitely prefer to work with DNG’s because the files are so much smaller than their corresponding TIFF’s.

Many thanks in advance,

Larry
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mlewis

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Re:
« Reply #1 on: March 01, 2014, 05:40:42 pm »

The DNG files are your original RAW files in a different container. ACR has put the lens profile in the metadata but hasn't changed the RAW data. As Lightroom doesn't recognise the lens profile it doesn't apply anything. It works with TIFF files as you are rendering an image with whatever edits you applied in ACR baked in.
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LawrenceBraunstein

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Re: Problems after importing DNG's into Lightroom
« Reply #2 on: March 02, 2014, 03:11:08 am »

I know why it didn’t work! It came to me in the middle of the night! Lightroom and Adobe Camera Raw work similarly (non-destructively) in that the changes we make in them are written as directives to a XMP file. Though both programs can read each other’s XMP files, the directives can only be executed if the program is capable of doing so (duh!). Obviously LR can’t implement a lens profile it doesn’t have!  As mlewis correctly points out, with a TIFF, changes we make are ‘backed’ into the file. That’s why LR was showing the TIFF images with the lens profile applied where as with the DNG’s it couldn’t.

Now, can someone please tell me why my brain was able to figure this out when it was supposed to be sleeping, and why it remained blank when it was supposed to be thinking! All I know is that I really need to get some sleep now. Thanks though, mlewis, for taking the time to respond to my query.

With best wishes,

Larry
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Tony Jay

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Re: Problems after importing DNG's into Lightroom
« Reply #3 on: March 02, 2014, 03:36:23 am »

Larry, as the Professor of Neurology says: "Thats the way the ball bounces!"

Tony Jay
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