None of the jpegs have UTC/timzeone information in the dateTimeOriginal or createDate attributes
The EXIF standard originally didn't allow for timezone data in these tags. It is now an option but not many programs use it and I'd be surprised at any camera that set it. The appropriate tags and the timestamps they match are
OffsetTime:
ModifyDate,
OffsetTimeOriginal:
DateTimeOriginal, and
OffsetTimeDigitized:
CreateDate.
There are a mix of jpegs which have either +00:00 or +01:00 at the end of the fileCreateDate and fileModifyDate
As Phil said. Basically, you can consider the system tags to be already written in UTC and the computer will automatically adjust the time displayed to match the current timezone set in the computer. There is no way to change the displayed value without resetting your computer time zone to UTC and then changing it every time daylight savings begins/ends. And that would mess up time zone data for everything else on the computer.
I would like to ensure the date is consistent for all time based attributes, so I'd like to ensure all dates are basically UTC0
For jpegs, the time stamps are considered to be local time for where they were taken. Most, if not all programs will treat it as such.
Just my opinion, but instead of rewriting the timestamps, I would consider adding the time zone to the appropriate places, and then using that combined value to write to
GPSDateStamp/
GPSTimeStamp, which is supposed to be UTC. It might prevent problems down the line.
With video, you run into the opposite problem. The
CreateDate is supposed to be UTC time.
