Synching Time Zones between iPhone and Camera

I didn't find a way to adjust the timestamp of the iPhone files. Even if I switch the computer to European time when I do the file transfer, the times are still 9 hours off when I put the computer back to Pacific time.

I found a different workaround. Instead of trying to fix the iPhone picture timestamps, I can use the trick on the Canon pictures.

I did these steps:

1) Set time zone to European time.

2) Insert Canon camera memory chip into Mac.

3) Transfer files form memory chip to Mac.

4) Airdrop iPhone pictures to Mac.

5) Restore time zone to Pacific (or automatic) time zone.

iPhone pictures can be air dropped before or after time change, as the time zone information is embedded within these pictures.

Now the timestamps of the iPhone and computer files are synched together. The timestamps are shown in Pacific time after time zone is restored to Pacific. Thus I have a lot of pictures with timestamps in the middle of the night, and different dates, because of the nine hour difference. At least all pictures are the same relative to each other.

And if one takes a trip to multiple time zones, then the transfers need to be done with corresponding time zones.