So, I really gave it a try and invested multiple hours. Either my spirit is not strong enough today, or it is currently not possible to synchronize owncloud 8.0.2 calenders with other applications.
To calm me down, here is a list of possible problems that are the reasons I failed currently with my mission.
What did I learned?
- use "CAdroid" to import your ssl-certificate if it is self created.
- the url "https://server/ owncloud base/remote.php/caldav/principals/user_name" looks like the one that should work
And finally, a list of most promising howtos (always have an eye to the creation date and the owncloud version used).