4 Replies Latest reply on Jul 7, 2008 8:18 PM by (Dmitry_Chastikov)

    EXIF time altered on conversion from PEF to DNG

      Converting Pentax PEF files from my *istDS to DNG using the Adobe DNG converter (4.1) results in the EXIF date/times all being shifted forward by six hours. I gather that the camera and the converter are miscommunicating regarding time zone. But the question is: short of running a batch operation to correct the times after the fact, what can be done about this to prevent this from happening in the future? I've also asked in the Pentax forums, in case someone there knows about any answers from the camera side of the equation.

      One workaround I've found is to generate XMP files for my images before running the converter. I have discovered that if the EXIF info is present in the XMP file - and ACDSee Pro 2 will do this for me by default as soon as I try to write copyright info or anything else to my PEF - then DNG will use that instead of the "real" EXIF info to populate the EXIF fields of the resulting DNG file. Actually, I'm kind of guessing it is still messing up the "real" EXIF version of the info in the DNG, but it is also reproducing the XMP version info, and ACDSee is using the latter, and that's probably good enough for now. Still, I'd prefer other alternatives.
        • 1. Re: EXIF time altered on conversion from PEF to DNG
          I see this same behavior when converting Canon CR2 files to DNG. DNG shouldn't be touching EXIF information in raw files!

          I'm on OS X 10.5 Leopard: can anyone confirm this behavior on Windows or on other versions of OS X?
          • 2. Re: EXIF time altered on conversion from PEF to DNG
            Level 1
            I still don't understand the issue *fully*. But examining my files with ExifTool, I see that the DNG converter is *not* in fact altering the EXIF info per se at all. What it is doing is adding an XMP block to the DNG file that contains a modified version of the DateTimeDigitized field. This modified version actually contains the time as shot, but it has the current time zone offset appended to it. That is, if the original EXIF dates read 09:00, and I am located in a time zone 6 hours behind GMT, the new DateTimeDigitized field created by the DNG Converter reads 09:00-06:00. Some applications will still display this as 9:00 AM, but others will display it as 3:00 PM - the GMT equivalent of 9:00 AM for folks in this time zone. In the case of the application I have been using (ACDSee Pro 2), if it sees time zone info on this field, it goes ahead and displays *all* times for the file in GMT, making it looks like the converter has modified more than it has.

            I don't know if the converter is wrong to append the current time zone offset, or if ACDSee (and, apparently, some other applications) are wrong to display the time in GMT. The folks are ACDSee are looking into whether and how they should change the behavior of their application. I would also suggest Adobe consider whether appending the time zone info from the computer on which the conversion is being run really makes sense (perhaps it could be made an optional behavior). But I am inclined to suspect the real problem is an overly-vague specification - there may be no definitively correct behavior here.

            So for me, this is enough understanding to feel like my workround is the way to go for me here. It actually suits my workflow better to generate XMP files before running the converter - it's the most convenient time for me to enter location information. Another workround would presumably be to run ExifTool to delete the XMP:DateTimeDigitized field immediately after running the converter.
            • 3. Re: EXIF time altered on conversion from PEF to DNG
              01af Level 1
              Marc Sabatella wrote:
              > I don't know if the converter is wrong
              > to append the current time zone offset ...

              Yes, it definitely is! I am having a lot of trouble with this $#!+ 'feature.' The problem is, the converter will add the computer's time zone which may or may not be the same as the time zone where the images where taken in. If the time zones differ (sometimes happens in my case) then the images end up being tagged with incorrect date-and-time information---and no regular way to keep it from happening or to correct it after the fact.

              So I wrote a Bridge script that tinkers with the time-zone info in the metadata ... but I don't really like this home-brew work-around; it still keeps causing me lots of headache. When I cared to complain the other day, an Adobe person had the guts to tell me time-zone part of the time stamp doesn't really mean anything anyway so I should simply stop worrying. Incredible! :(

              -- Olaf
              • 4. Re: EXIF time altered on conversion from PEF to DNG
                No, not that straightforward. The original PEF does not contain any time-zone information, and therefore the date-time stamps it contain are in unknown coordinate system. DNG converter, followed by CameraRAW, or whatever, just adds yet another time stamp where it appends the current time zone info to it. Reasonable default, I'd say. I wouldn't ever notice that as all the the programs (but one :-) show the date taken correctly. The only one, namely ACDSee Pro 2 build 219, I assume ACDSee 10 may have the same bug, used to show the time converted to GMT. Upgraded to build 238, and the bug was "kind of fixed" - it calculated the time converting it to GMT using the offset added by Adobe (+04 in my case as it is Moscow which today is 4 hours ahead of GMT, summer time), and then back using the offset from the top of its head +3. I think that is because my time-zone is "GMT+03, Adjust for daylight saving time". That's it. And the Adobe guy was right saying that the time-zone part was not really meaning anything.