I know that, R C-R. The missing time zone in the EXIF has been the biggest problem for me, since i started with digital photography, and the better time zone handling was the main reason for me to switch from iPhoto to Aperture.
The bug I am referring to does not apply to the EXIF in imported images, but the time zone data for image versions in photo libraries. Photos migrates the time zone data in Aperture libraries and iPhoto libraries incorrectly. And Photos even displays the time zones incorrectly, when a timezone is specified in Photos using the Adjust Date and Time command.
Apple's photo library application manage time zones, when we specify the time zone on import, but this is broken in Photos. All edited image versions in my iPhoto Libraries and Aperture libraries have time zones assigned to the versions, and the time zones are shown correctly together with the dates in the info panels in both applications.
But when Photos migrated the libraries it ignored the time zone settings that are stored in the original libraries.
And now the sorting of photos taken with my iPhone and the Lumix cameras is a mess.
For example, in my original Aperture library are photos taken with my iPad and with my Lumix camera. My iPad will usually be set to the local time zone and the Lumix cameras are always set to UTC. When importing I specify in Aperture that the correct time zone for the Lumix cameras is UTC and for the iPad for example GMT-8 for Anchorage.
For example, Aperture will show the date and time correctly for two photos taken at the same time - 11:00 UTC for the Lumix photos and 03:00 GMT-8 for the iPad photos and sort the photos side-by-side. When I open the library in iPhoto, the dates and times are also shown correctly. But the migrated library in Photos shows the two photos eight hours apart. The times are shown as 11:00 GMT+2 for the Lumix and 03:00 GMT+2 for the iPad photos. Photos simply ignores the time zone data in the libraries it migrates and uses the current system time zone name, when it displays the times. The times in all photo libraries I migrated are now a messed the photos from different cameras are no longer correctly sorted.
IOW, the timezone is meaningless unless the location is known. All Exif date-time metadata is "camera-local,"
It is meaningless only for EXIF tags. EXIF tag capture date format is ridiculous, because it does not contain the time zone. That is why Aperture makes it possible to add the timezone when photos are imported. And Photos is also allowing to set the time zone. It is silly to specify times without the time zone as part of the time.
And the time zone should not be derived from the location.
That is exactly what is causing the problems when importing photos a day later, after we are in a different state.