gphoto2 –set-config datetimeutc=now

synchronized the camera (using “datetimeutc” without setting TZ).

But checking the time by taking a picture of a precise clock revealed a difference of 1.3 seconds and 1.6 seconds on the next try. That’s worse than setting by hand. Never expected that!

As the KDE clock seconds display is delayed rather often, I’ve used a program I’ve written in Ada which also shows two digits below the seconds without obscuring these digits by a too long exposure time of the camera. The program was tested against
xclock -digital -update 1 -strftime “%Y-%m-%d %H:%M:%S”

So the clock pictures taken allow the comparison of times including the EXIF “subsecond” variable.

So I’ll continue to use clock pictures and use exiftool for time correction of the pictures taken.