From 1911 to 1913 he studied in Munich at a private school run by Wladimir Magidey (born 1881) and at the Akademie der bildenden Künste under Peter Halm and Carl Johann Becker-Gundahl.
Akademie der bildenden Künste in Stuttgart under professors Heinrich Altherr and Adolf Hölzel, until the First World War put an abrupt end to his education and turned him into a medical orderly in the army on the Western Front.
In addition to his unique portraits of adults and children, views of towns and cities, landscapes and still lives, throughout his life he was a frequent visitor to coffee shops, portraying them in paintings, diary entries and poems.
Whether in watercolor, pastel, drawing, lithography or oil painting, his street and café house scenes, landscapes and portraits always showed him to be an incorruptible chronicler of changing times and many socio-political events.
Ahner left copious diary entries which are preserved with the rest of his written estate at the Sächsischen Landesbibliothek – Staats- und Universitätsbibliothek Dresden since the 1980s.
Most of the foundation's works are stored in the Weimar City Museum and the Thüringer Freilichtmuseum Hohenfelden, though around 200 of them are on loan to the Thuringian State Parliament in Erfurt, the Buchenwald Memorial and other sites.