@paperdigits: many thanks.
On source forge I found lensfun 0.3.95 from 2018. The contained database seems to be not that updated than the version in AppImage up to 17th of may this year. my cam (pentax K-70) is included, one of my newer lences (Pentax HD 55-300-DA …PLM…) is not.
If I change the lensfun entry in options file to DBDirectory=./share/lensfun/version_1 lensfun seems to work. But the database included in the AppImage doesn’t contain the above mentioned newer lens and my cam although some AppImages of dev versions til the version from april 17 I think contained this lens too.
So: is it possible that the database included in actual AppImages uses an older version of the lensfun database compared to versions some two weeks ago?
If someone knows the link to older dev versions and can post it here, I will try older versions to find the possible change.
ping @Carmelo_DrRaw
many thanks
Heinrich