EXIF time stamps-General Discussion

MetaImage
#1

Hello Jeremy,
General discussion about time stamps in photo (video) files.
I know you had a little difficulty with editing time fields a year ago so I consider you an expert on this issue.

Apple appears to be one of the few applications that adjusts the time information when photos are exported. From what I have read over the past few days the time zone issue is poorly implemented and thus needlessly complicated. I am at the point that I will deal with Apple and their ‘adjustment’ of time, with manual editing, and hope other programs do not follow suit.

****3:30pm update on this post, the problem, time being ‘adjusted’ occurred when I created a sharable folder in Photos and not during the exportation of the files. ****

Am I over simplifying or overlooking something regarding the EXIF timestamps?
Your comments:

Thank you, -Fred

Back story:
We took a three week vacation driving across three time zones. I had a Nikon camera and our iPhones. I would update the time on the Nikon based on the current time. I.e. Yellowstone National Park the lunch lady said it was 12 noon, my Nikon camera would be set to 12 noon. The iPhone would automatically update the time and also be timestamped as 12 noon. At home I wanted to merge the Nikon and iPhone photos. The fun began.

I exported the iPhone files from Photos. I then appended the date and time to the beginning of the iPhone and Nikon file names. The time of the EXPORTED iPhone photos were off by 2 hours, the two hours is the time difference from my home and Yellowstone National Park.

After two days of googling this issue I have determined that there is indeed an EXIF: time zone field but it is very limited in implementation. You have one post dated FEB22 by fluent_retired0v that mentions the issue, His is the ONLY article I read in support of using the timezone field. In his thread you mention EXIF:TimeZoneOffset.

In some abstract way I might be able to imagine a need to complicate the creation time the photo was taken, but when UTC, GMT, daylight saving time not to mention sun spots, rotational lag and geopolitical issues are thrown into the mix it is time for Occam’s razor. A simple time of day based on the sun at the current position is a better approach. If you want to throw in positional data that should be a separate topic.

#4

Hello Fred,

I apologize for the delay and want to express my gratitude for your first contribution.

Before responding, I must clarify that I don’t consider myself an expert in this field. However, I am committed to understanding metadata and providing the easiest and most comprehensive tools to assist people. If you require assistance from true metadata experts, I recommend seeking help on the exiftool forum at this link: ExifTool Forum - Index

As you have likely gathered, handling metadata is complex because each application treats it differently.

For instance, if you wish to set an EXIF date in an image, you can choose to modify the EXIF:DateTimeOriginal tag. If you set it to 2023:08:03 03:00:00, it implies that the photo was taken today at 3 AM somewhere in the world. If you leave it as is, there won’t be any issues, as applications will display this date assuming you took the photo in your current location.

However, if you want to add more information, you can set a time zone with tags like EXIF:OffsetTime, EXIF:OffsetTimeDigitized, and EXIF:OffsetTimeOriginal. This is where things get more complicated. Some apps will display the photo as if it was taken at 3 AM, while others will convert the date to your current location’s time zone.

You can observe this difference between Photos and Finder. While Photos shows you the date in the photo’s time zone, Finder displays the date in the system’s time zone.

Please note that MetaImage supports time zone tags, even if they are not displayed by default. You can manually add them via the tag manager.

I believe the app is just converting the date to your current location, offset by 2 hours.

I’m a bit confused. Do you see any differences between your main library and the shareable folder?

Jérémy

#5

Jeremy,
Thank you for your comments. I have spent more time than I cared too on this subject and determined, as you said, it is up to the application on how the D/T is handled and there are many inconsistencies.

The exported iPhone photos do have the EXIF:OffsetTime, EXIF:OffsetTimeOriginal and EXIF:OffsetTimeDigitized values set, the EXIF Offset Schema showed -No Value-

Now knowing about the EXIF:offsets tags, the math works, iPhoto taken in timezone -7 @ 12:30 PM, exported in timezone -4 now shows 3:30 PM. If I send the exported iPhoto to you in France and say it was taken in Seattle, WA USA and you looked at the timestamp 3:30 PM I doubt even Phil Harvey or Tim Cook would know the photo was taken at noon… :slight_smile:

Thank you for your time and comments, -Fred