# To DNG or not to DNG



## Gene_mtl (Mar 24, 2012)

Think I just went down a one-way street, one that I'll not take again.

Background.

I keep about six months of images on my main desktop hard drive. After which I do a clean up, removing (deleting) cr2 & related xmp files from a folder for those images that did not get final processed.  I re-sync the folder in Lightroom and after burning the folder contents to a DVD, I move the entire folder (and related subfolders containing the full processed JPG, which also exists on-line in galleries on SmugMug) to an external hard drive.

Was suggested to me a while back that I would benefit by converting the cr2 & xmp files to DNG as it would result in smaller files. So with my recent upgrade to LR4, I thought I might try the conversion.

In LR2 I don't remember be asked what ACR level I wanted compatibility with.  But when asked in LR4 I choose ACR5.4 compatible with PS CS4. I also accepted the suggested medium preview size.

After conversion, I could not see the DNG preview in Windows Explorer.  Found out I needed some sort of Adobe codec, which I downloaded and installed.  As for file size, while some were a meg smaller than the cr2 file, almost as many were 1-2 megs bigger.

To top it off, my default image viewer - irfanview - can not display the previews correctly.

I am certainly not seeing any advantage to converting to DNG.   Have I missed something?


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## clee01l (Mar 24, 2012)

Gene, My files out of the camera are already DNG.  If they were not, I would not bother going to the extra time and trouble to convert some proprietary RAW format to a non proprietary RAW format.


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## Gene_mtl (Mar 25, 2012)

Thanks Cletus fro the feedback. So there really isn't any advantage to converting to DNG.


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## Hal P Anderson (Mar 25, 2012)

Gene,

There's one nice advantage to DNGs: they contain a checksum of their image data, so Lightroom and ACR (and perhaps other apps) can immediately tell if the files have been corrupted.

Hal


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## carson (Mar 25, 2012)

I convert all CR2 fies to dng on import to LR and don't use xmp's at all, always found them to be a pain. As for viewing dng out side of LR that really isn't a problem as most new photo viewers, at least in my experience now support dng. I use ACDSee pro as I already owned it, it just didn't work well as a DAM solution but is a god viewer. FastStone is also a good solution.
Personally dng works well for me and I did go back and convert mst of my old files but perhaps that isn't the best solution for everyone, for some it may be best to just use dng going forward and leave old fies the way there were.


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## Victoria Bampton (Mar 25, 2012)

Gene, when you say irfanview doesn't display the previews correctly, what does it display?


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## Gene_mtl (Mar 25, 2012)

*Hal* and *carson*: Thanks for the added info.

*Victoria*: When using irfanview 4.27, what I saw was a half height stretched preview.  So I checked and sure enough there was a later version (4.32) SO I downloaded it with its related plug-ins. With that version I am seeing something that looks like it has been cut many times hroizontally, so it is still only half-height.


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## hman (Mar 25, 2012)

This may be a really stupid question. With my previous camera, I coverted PEF to DNG on import. My images now come out of my Pentax K-x as DNG. If I was to import into LR4 with Convert to DNG, does LR try to convert the DNG files again?


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## Victoria Bampton (Mar 26, 2012)

Gene, might be worth letting them know, since they're listing it as compatible with DNG.

hman, it would update the DNG format to a newer spec - Pentax likely create an earlier specification DNG file, without the improvements like tiling for faster reading.


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## hman (Mar 26, 2012)

Thanks- I'll leave the setting alone.

Harvey


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## Gene_mtl (Mar 26, 2012)

Some additional info on the DNGs created out of LR4. I am having the same issue using Fast Stone Picture viewer.  While it displays the small thumbnail properly in its explorer (browser?) window and in the preview window, if you attempt to view it full size, you see the same thing I posted previously when viewed in irfanview.

This issue is with the LR's DNG conversion. I can open DNGs I created in LR2 in both software without issue. Only the ones I created in LR4 using the parameters I listed above are giving my problems.  As I never used LR3 I can say whether DNGs created in it would cause the same issue.

Obviously Adobe changed things in the conversion and these third party viewers have not kept up with the changes.

Not Adobe's fault. But still another irritant.


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## Pete_S (Mar 26, 2012)

Gene_mtl said:


> Some additional info on the DNGs created out of LR4. I am having the same issue using Fast Stone Picture viewer.  While it displays the small thumbnail properly in its explorer (browser?) window and in the preview window, if you attempt to view it full size, you see the same thing I posted previously when viewed in irfanview......
> .



Gene, I've tracked the display problem down.  When Exporting to DNG, LR4 defaults to embedding fast load data, a new feature in LR4 intended to allow faster loading.  Uncheck this option prior to the conversion and your LR4 converted DNG will display as it should full screen in both Irfanview or Fastone Image Viewer.


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## Gene_mtl (Mar 27, 2012)

Thanks Peter. Really appreciate you tracking down the problem.  Don't remember that checkbox.  <Shrug>  I guess there is no way to convert a DNG with  'fast load' to a DNG without 'fast load'?

Actually I just ran a test. LR4 allows you to Convert to DNG.  Ended up with a file with an extension [filename].swp.  Moving the original dng to another folder and renaming the [filename].swp file to [filename].dng using Windows explorer, and everything is hunky-dory!

Further testing seems to indicate that the *.swp file issue may be because I was initially working on files on a network. It may be that LR does not have permissions to delete  and rename files on a network drive. I assume this because when I moved the folder down to a desktop drive, there were no *.swp files and the converted dng displayed properly in irfanview.

Not sure if 'Fast load' is checked by default. Or in my stumbling around, I inadvertently check it. It is now _unchecked_ in my software.


Many thanks to _*Peter_S*_ for discovery the cause.


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## Victoria Bampton (Mar 27, 2012)

Great job Pete!!!  That should be reported to those software developers as a bug, as they should just be ignoring the fast load data that they don't understand.  It's only an extra set of data.


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## Pete_S (Mar 27, 2012)

Victoria Bampton said:


> Great job Pete!!!  That should be reported to those software developers as a bug,.......



Will do, Victoria. :nod:


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