Lightroom: Tiff - DNG can loose original capture date

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When in Lightroom and I alter a TIFF file to a DNG file the original capture date is lost and replaced by the date and time it became a DNG file... To take advantage of the DNG process this is a major problem. And when importing a TIFF file using the copy and convert to DNG, the TIFF file is not converted... another disadvantage. I am guessing that no photographers I know want to loose the original capture date. Please help solve this problem
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rich berrett

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Posted 3 years ago

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John R. Ellis, Champion

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"When in Lightroom and I alter a TIFF file to a DNG file the original capture date is lost and replaced by the date and time it became a DNG file."

If the TIFF has a capture date stored in its metadata, then Library > Convert Photo To DNG will correctly preserve that capture date in the DNG.

However, if the TIFF file doesn't have a capture date, then LR will display the file's last-modified time (as maintained by the operating system) under its thumbnail in Library mode. When you convert the file to DNG, the DNG won't have a capture date either, and LR will show the last-modified time of the DNG (which is when the DNG was created) under its thumbnail in Library mode.

To avoid this, make sure the TIFF actually has a capture time stored in its metadata. To do that, select the file, do Metadata > Edit Capture Time, and click Change. You can do a whole batch of photos at once that way, and LR will set each photo's capture time to its own last-modified time.
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Steve Sprengel, Champion

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You need to share a PUBLIC link not the URL you see when on the website which only works for you when you're logged in.

Try right-clicking on the file or folder and choose Share--if that's how it still works.
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rich berrett

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here is the public folder link: https://www.dropbox.com/home/Public#
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Steve Sprengel, Champion

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That is not a public link. It only works for you. Use the share function to create a share link. It'll have a bunch of gibberish in it to make it unique to your files.
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John R. Ellis, Champion

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Yup, I downloaded it and am looking at it now.
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David Converse

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Perhaps I am missing something but why would you convert a TIFF to a DNG? The whole idea of DNG is a universal RAW interchange format. Only a few cameras save directly to TIFF and those apply processing, just like saving to JPEG in-camera.

If you already have a TIFF, you gain nothing by converting to DNG.
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rich berrett

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My understanding based on Kelby's latest book (p.44), a dng file is about 20% smaller, and a separate sidecar is not needed. I know he is talking about the comparison between DNG and RAW, perhaps I am mistaken to assume the same applies to TIFF and RAW. Do you know?
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John R. Ellis, Champion

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LR doesn't use sidecars with TIFFs, JPEGs, PNGs, and DNGs -- with all of those formats, it writes the metadata directly into the file.
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rich berrett

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is a dng file smaller than a tiff?
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John R. Ellis, Champion

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I'm not an expert on that issue, but I think it depends on the image and the compression used in the TIFF. The example TIFF you provided has no compression and is 90 MB. Saving it with LZW compression increases its size to 110 MB and with Zip compression decreases its size to 83 MB. The DNG is 69 MB. So at least in this instance, the DNG is significantly smaller.
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John R. Ellis, Champion

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Independent of your desire to convert to DNG, you've tripped over a nasty LR bug, in which LR behaves inconsistently and confusingly when dealing with pics and videos that are missing capture dates in their metadata:

http://feedback.photoshop.com/photosh...

One symptom is that LR's Library grid view will not sort your thumbnails properly by capture date; another symptom is that it won't write the displayed capture date back to the file. Adobe has never prioritized a full fix for this bug, since LR's main focus has always been on images produced by digital cameras (which have capture dates), and they've never implemented video metadata properly.

In your second screen shot, the file Italy-122-richberrett-2.tif shows 8/20/2015 8:03:45 AM above its thumbnail, whereas the Metadata panel shows 10/10/2009 2:38:52 AM for capture date. This situation occurs when the file's metadata is missing a capture date at the time of import, and LR will behave inconsistently, as detailed in the bug report above. (Precisely which date LR chooses for the Metadata panel has changed over the years.)

To eliminate the inconsistency, you'd need to get a "real" capture date assigned to the pic and stored in its file metadata. Independent of converting to DNGs, this would be desirable, if you want to ensure that your capture dates are properly preserved going forward.

Simply invoking Metadata > Save Metadata To File won't save the capture date back to the metadata.

The recipe that I provided you previously won't work in your particular situation (due to the presence of EXIF:ModifyDate in the metadata). If you invoke Metadata > Edit Capture Time on that TIFF, the Edit Capture Time dialog will suggest a corrected date/time that's the same as the date/time under the thumbnail, not the date shown in the Metadata panel's capture time (which is the date you want).

The only possibility is to try Edit Capture Time again, selecting the option Change To File's Creation Date. Since you are on a Mac, the file's original creation date may still be preserved and match the actual desired capture date shown in the Metadata panel. But many tools on the Mac (including LR) don't preserve file creation dates, and if you've lost the original file creation dates, there's no easy recipe to fix the problem (or at least that I know of).

In that case, I can think of only one solution, which requires skill writing scripts with command-line tools. You could use the List View plugin to extract into a text file the full file paths and the capture dates shown in the Metadata panel. Then you could write a script using the free Exiftool that takes those file paths and capture dates and stores the dates in the files' metadata. Finally, you'd reread the metadata back into the LR catalog using the Metadata > Read Medata From File. Even for someone skilled and knowledgable, this would likely take a few hours to complete and verify.

You might add your vote and opinion the bug report above, to make it a little more likely Adobe will prioritize a fix.