Trained as art historian, Finsler became photographer as autodidact. He started to take still lifes and developed his own aesthetics with the New Objectivity movement. At the beginning of 1920s Most chocolate company in Halle commissioned him to take pictures of the factory and manufacturing process: these images became part of the FiFo touring exhibition in 1929. He became director of the photography course at the Kunstgewerbeschule in Zürich and taught there for nearly 26 years.