8 Replies Latest reply on Sep 16, 2009 12:56 PM by xbytor2

    DNG and MESZ timestamp / sony A100 RAW conversion

    Tschubi80

      Hello,

       

      i have a question regarding the timestamp within the EXIF metadata after the RAW to DNG conversion for my A100 pictures. Today I have seen that the timestamp betwen the RAW original file and the converted DNG file differs about 3 hours. I can't explain me this difference by myself. Has someone here an idea for this difference? I use the Mac Version of the actual free DNG converter. My timezone is MESZ/CEST what also means UTC+2 at the moment if I'm right. So 2 hours difference I could imagine because of such a time zone missmatch, but not 3 hours. But if i look at the RAW files the timestamp addition also shows MESZ like in the DNG after conversion. The main reason why I want to use DNG format is the linkage with my GPS logger data. But if the timestamps will convert wrong, this would be a no go for me.

       

      Thanks for your help.

       

      Greetings,

       

      Tschubi

        • 1. Re: DNG and MESZ timestamp / sony A100 RAW conversion
          xbytor2 Level 4

          Take a look at the metadata of both files with exiftool to see if you can make better sense of what's going on.

           

          Ex:

          $ exiftool DSC_0491.dng | grep 2009
          File Modification Date/Time     : 2009:08:30 13:33:31-05:00
          Modify Date                     : 2009:08:16 17:37:55
          Date/Time Digitized             : 2009:08:16 17:37:55.00-05:00
          Date/Time Original              : 2009:08:16 17:37:55
          Create Date                     : 2009:08:16 17:37:55
          Preview Date Time               : 2009:08:30 13:33:30-05:00
          Create Date                     : 2009:08:16 17:37:55.00
          Date/Time Original              : 2009:08:16 17:37:55.00
          Modify Date                     : 2009:08:16 17:37:55.00
          
          $ exiftool DSC_0491.nef | grep 2009
          File Modification Date/Time     : 2009:08:29 19:21:42-05:00
          Modify Date                     : 2009:08:16 17:37:55
          Create Date                     : 2009:08:16 17:37:55
          Date/Time Original              : 2009:08:16 17:37:55
          Create Date                     : 2009:08:16 17:37:55.00
          Date/Time Original              : 2009:08:16 17:37:55.00
          Modify Date                     : 2009:08:16 17:37:55.00
          
          • 2. Re: DNG and MESZ timestamp / sony A100 RAW conversion
            boardhead_ Level 1

            Without more details I'd only be guessing, but what about daylight savings time?

            • 3. Re: DNG and MESZ timestamp / sony A100 RAW conversion
              Tschubi80 Level 1

              Hello,

               

              thanks for the tip with exiftool. OK, I had a look at the metadata and here are the results:

               

               

              $: DNG_Tests tschubi$ exiftool DSC07064.ARW | grep 2009

              File Modification Date/Time     : 2009:08:28 11:26:08+02:00

              Date/Time Original              : 2009:08:28 11:26:07

              Create Date                     : 2009:08:28 11:26:07

              Modify Date                     : 2009:08:28 11:26:07

               

              $: DNG_Tests tschubi$ exiftool DSC07064.dng | grep 2009

              File Modification Date/Time     : 2009:08:30 19:37:00+02:00

              Modify Date                     : 2009:08:28 11:26:07

              Date/Time Digitized             : 2009:08:28 11:26:07+02:00

              Date/Time Original              : 2009:08:28 11:26:07

              Create Date                     : 2009:08:28 11:26:07

              Preview Date Time               : 2009:08:30 19:37:01+02:00

               

              Ok, things are getting a bit more confusing to me ;-). If I'm right, everything seems to be converted correctly - right? Then I have to challenge my MAC software I think. If I simply use Leopards "Preview" (dt.: Vorschau) I get the following information for the EXIF tab (see attached picture1) and for the TIFF tab (see attached picture2). As you can see, the TIFF tab shows the right original timestamp, but the EXIF tab shows the wrong time. In Aperture I only get the timestamp information with the wrong time out of my metadata (see picture3). If I export a jpg out of my working copy from there, this jpg then only has this wrong timestamp in its metadata information. So this is a bit strange regarding my workflow. Any suggestions? And please don't say I should use Lightroom ;-). This is another theme, and I have my own reasons why I use Aperture instead of Lightroom. As I'm in an Adobe forum I hope this fact will not end up in one more endless philosophie discussion ;-).

               

              Thanks again for your ideas and suggestions.

               

              Greetings,

               

              Tschubi

              • 4. Re: DNG and MESZ timestamp / sony A100 RAW conversion
                xbytor2 Level 4
                 If I'm right, everything seems to be converted correctly - right? 

                Your exiftool results are consistent with mine, so they seem OK.

                 

                Then I have to challenge my MAC software I think.

                I also suspect that this is where the problem may or in specific apps that show the problem.

                 

                The +2.00 from exiftool (and elsewhere) is recognizing MESZ correctly (UTC+1 + Daylight Savings Time).

                All of the dates do have timezone information in the file even if it is not displayed that way in the exiftool output.

                 

                Your metadata appears to be correct. Software interpreting it may not be correct. In the exiftool output for the

                image I posted, exiftool is reporting 17:37 (UTC-5) and Aperture is showing 06:37. It's as if it's adjusting for

                UTC-6 twice then making the +1 adjustment for Daylight Savings Time. This is consistent with what you're seeing.

                 

                tl;dr;

                Your DNG files have the correct times in metadata. Some of the software you are using does not correctly handle timezones.

                • 5. Re: DNG and MESZ timestamp / sony A100 RAW conversion
                  Tschubi80 Level 1

                  Thx for the answer xbytor2.

                   

                  Then it might be a subject for an apple or aperture forum I think. But what I'm still wondering about is, that the timestamp from the RAW (or ARW files in this case) are interpreted correctly. So the missmatch is not only a wrong timestamp interpretation in general e.g. by Aperture. It looks like a specific Aperture, Preview ... and DNG timstamp problem. I searched for some preferences in Aperture regarding timezones, but I could't find anything. For sure - what I can do is correcting the timestamps at import time into Aperture. But that's not really what I want to do.

                   

                  Greetings,

                   

                  Tschubi

                  • 6. Re: DNG and MESZ timestamp / sony A100 RAW conversion
                    xbytor2 Level 4

                    If I do a simple exiftool DSC_0491.nef I get all of the times in local time (17:37). The timezone is in a different exif field called Timezone which is set to -6.00. That would be the TZ that I have set in my camera. Except that it didn't adjust for daylight savings time. I'll have to poke around in the camera and see what's wrong there or if it really matters.

                     

                    When I check in the DNG file, I see exactly the same thing. And when I check the XMP version of the metadata I see stuff like this:

                         <exif:DateTimeOriginal>2009-08-16T17:37:55.00-05:00</exif:DateTimeOriginal>

                    so I know the appropriate transformations are taking place here as well. And, oddly enough, the DNG times have the daylight savings time adjustment.

                     

                    Your problem is apparently downstream with the Apple tools.

                    • 7. Re: DNG and MESZ timestamp / sony A100 RAW conversion
                      dfranzen_adobe Level 3

                      I think what you are seeing is a longstanding mis-match between how Exif and XMP record date-time values, and--possibly--a failure on the part of some of your software to understand how to use date-times read from XMP for the Exif date-time properties. When reading an Exif date-time from XMP, the UTC offset should always be ignored when interpeting the date-time--it has no meaning.

                       

                      Three date-time metadata properties are involved in this issue, in XMP they are stored as the following properties:

                       

                      exif:DateTimeDigitized

                      exif:DateTimeOrigional

                      xmp:ModifyDate

                       

                      When Adobe software reads Exif metadata from files, it maps the values in the Exif tag(s) to XMP properties. The XMP is stored inside the file when the software saves or updates a file (or sidecar .xmp file for RAW files).

                       

                      For exmaple, the exif:DateTimeDigitized the value is taken from two Exif tags, 0x9003 ("DateTimeDigized") and 0x9291 ("SubSecTimeDigizied"). See Part 2 of the XMP Specification for more details about how Exif is mapped to XMP.

                       

                      The Exif specification defines no way to record a time zone or UTC offset for its date-time values. If you are trying to figure out what time the picture was taken reading Exif, it's impossible to know what time zone is correct. If cameras are recording the time zone, they are storing it in propritary metadata in the file, and not in a standard Exif tag.

                       

                      Unfortunetly until recently the XMP Specification defined a date-time string format that requires a UTC offset. That's the mismatch. So, what's the software do when it's supposed to write a UTC offset, but doesn't have one to go with the time? Traditionally Adobe software uses whatever time zone your computer's clock has at the time the XMP property is created (that is, when the Exif is read).

                       

                      So, if your camera's clock was set to record 2009:08:28 11:26:07 in the Exif, and you convert your raw file to a DNG with a computer in Europe, you're probably going to get something like 2009-08-28T11:26:07+02:00 in the XMP. But if I convert the same RAW file to a DNG here in Seattle, I'm going to get 2009-08-28T11:26:07-07:00.

                       

                      Of course the right thing to do would be to just write 2009-08-28T11:26:07 in the XMP, leaving out the time zone designator (TZD). Expect that in the future. The XMP Specification now says that the TZD is optional and that "software should not assume anything about the missing time zone," but even the most recent release of the DNG Converter (5.5 as I write this) has not yet caught up with this update to the XMP Specification, and it still writes the bogus TZD. Also, any XMP written by older Adobe software will have the TZDs.

                       

                      What Adobe software like Bridge and Lightroom have done tradtionally is to ignore the TZD in the XMP when using these dates. You'll notice that browsing DNGs with the dates 2009-08-28T11:26:07+02:00 and 2009-08-28T11:26:07-07:00, and running Bridge anywhere in the world (that is regardless of the the clock's Time Zone setting on your computer), the metadata panel will still show you that you took the picture at 11:26 am on August 28, 2009. If other software is trying to shift dates to local times based on the UTC offsets recorded in XMP for these dates, that's a bug.

                       

                      Note that unlike other date-time values in Exif, the Exif specification says that the GPSTimeStamp is UTC, so this problem does not affect GPS metadata.

                       

                      I mentioned the XMP specification a few times, you can download it here:

                      http://www.adobe.com/devnet/xmp/

                       

                      -David

                      • 8. Re: DNG and MESZ timestamp / sony A100 RAW conversion
                        xbytor2 Level 4

                        Thanks for the clarification, David. This will definitely help isolate date-related metatdata problems in the future.