Photo's EXIF data Time Zone OffSet Question

I have just taken a trip to Italy took pictures with both my Canon SLR and multiple iPhones.
I copied all images  when I got home and wanted to make sure all TimeStamps are properly sequential.

  1. My SLR time was adjusted a few days into the trip to match the time zone I was in. So the first 100 or so pictures were timestamps with Eastern Standard Time (-6 hours from Italy). After I changed the time on the SLR all Date Taken were correct.
  2. iPhones time adjusted to the time zone when we landed do all images Date Taken were correct.


So I wanted to make sure that the first 100 or so images taken with my SLR had the correct Date Taken and not be offset by -6 hours.  So what I did was modify the Date Modified +6 hours, but this did not change the Date Taken and I know that this data is EXIF information and cannot be changed the same way I did for date modified.
What I did notice when examine this, Date Taken vs Date Modified on the iPhone EXIF were offset by 6 hours.  So Date Taken was the time in Italy, but the Date Modified is the time in NY.  This data was not manipulated in any way.

Can anyone shed some light on why the iPhone timestamps are offset like that?
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yo_beeDirector of Information TechnologyAsked:
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Christopher Jay WolffWiggle My Legs, OwnerCommented:
Sorry, but it's a bit confusing about what you did and what your looking for.  Date Modified should change every time you modify the file, should it not?

To correct any errors you might try this article on adding or editing EXIF data.
http://www.howtogeek.com/203592/what-is-exif-data-and-how-to-remove-it/
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Christopher Jay WolffWiggle My Legs, OwnerCommented:
I see.  I was  too hurried by a phone call earlier.  It may have something to do with the iPhone home time zone setting.  Or did you change your home time zone on the iPhone?   I understand you to mean the iPhones automatically adjusted to GPS and set correct current time zone when you landed in Italy.  Then your home time zone would still be 6 hours offset.  I'll see if I can find something about it.  Or maybe someone else knows here.
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yo_beeDirector of Information TechnologyAuthor Commented:
Sorry for the confusing post, but your second reply is what I am referencing.

I did not modify anything. I was just noticing that date taken and date modified are offset by 6 hours.
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Christopher Jay WolffWiggle My Legs, OwnerCommented:
It sounds like an oversight or bug for Apple to fix.  I'll try and confirm.  The TimeZoneOffset exif tag may not get handled properly, or I'm not understanding it.  Here is a sort of definition from exiv2.org.

Exif tags.
from this link.
http://www.exiv2.org/tags.html
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Christopher Jay WolffWiggle My Legs, OwnerCommented:
Over the last couple weeks, using email and phone, went from Apple tech support to Dev tech support, and eventually got turned away sort of.   Today, Dev support called tech support, and then transferred me to someone at reguar tech support to help with EXIF data and she accepted a new email from me about this.  She is supposed get back to me.
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yo_beeDirector of Information TechnologyAuthor Commented:
You are going well far and above to get me an answer. Thanks
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Christopher Jay WolffWiggle My Legs, OwnerCommented:
Your quite welcome.  Not too much effort really.  I just really like conclusive answers if possible.
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Christopher Jay WolffWiggle My Legs, OwnerCommented:
Today I heard from AppleCare.  She said Engineering responded to her inquiry regarding this issue,  by requesting screen grabs that illustrate your opening statement above which says...

What I did notice when examine this, Date Taken vs Date Modified on the iPhone EXIF were offset by 6 hours.  So Date Taken was the time in Italy, but the Date Modified is the time in NY.  This data was not manipulated in any way.

If you post them here, I'll send them to her.  Sound good?
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yo_beeDirector of Information TechnologyAuthor Commented:
Here is a screenshot of one of the pictures.
Note the Date Taken and Date Modified  .
img1
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Christopher Jay WolffWiggle My Legs, OwnerCommented:
Update for today 10/24/2016:

10/13/2016 - Sent your screen to Apple support.
10/14/2016 - She thanked me and said she would forward to the team.
10/19/2016 - I emailed her to ask how long we might expect to wait for developments..
10/19/2016 - She emailed "not quite yet" and confirmed she had sent the PDF to them, and she will reply when she hears from them.




I wonder if there is a way to rationalize the times you are seeing, which might explain what they're doing as a type of work-around.  If you sorted your photos by date and time with some mixed locations between NY and Italy, then you might only want to sort by one column.  So the accurate column by which to sort would be Date Modified.  The NY time in Date Modified is the exact moment the picture was taken, it's just a way to track the correct time order of photos relative to one place.  It is fairly odd and seems erroneous, but maybe there is nothing in EXIF to allow handling how to remind the user they were in a different time zone for some photos,

I was also wondering if you noticed if the Date Modified was Italian time while you were in Italy, and then when you land in NY the iPhone again automatically adjusts by GPS to the new time zone and automatically adjusts the Date Modified EXIF data without your knowledge.  In other words, could the Date Modified time have been automatically changed without your knowledge, to NY time as shown in your screen grab, when your iPhone woke up on the tarmac in NY?

And then of course, for the sake of the thread, could you spare a day to fly at least as far as Chicago to debunk this theory?  Ha!!
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yo_beeDirector of Information TechnologyAuthor Commented:
My rational i came up with is that the date taken and modified are independent from each other on the iPhone. Where one floats with the present geo-location and one is a time stamp at the location time it was taken. My guess is if I adjust my device to another time zone.

I was not aware during Italy, so I never thought to check.

Any ideas to test?
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Christopher Jay WolffWiggle My Legs, OwnerCommented:
I would go to Settings, Privacy, Location Services, and turn it off.

Then I would go to Settings, General, Date & Time, and turn off "Set Automatically" and enter a city in a different zone.  Like the city in Italy where you were or anywhere in a different zone where you know how many hours away it is.

Take a picture and check Date Modified.  Then change time zone back to NY and check again.  Might work.  Does that sound about right?
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Christopher Jay WolffWiggle My Legs, OwnerCommented:
HI again.  Was wondering if testing with that method in my last post provided any useful information.

I had a voice mail from Apple but it was not helpful.  They asked me to call again.
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yo_beeDirector of Information TechnologyAuthor Commented:
I did try the turning off the Location service and forcing it to +0600, but the desired results did not happen.
I am not sure if there is something in the metadata that the phone home geo-location is EST.
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