Trained as an art historian, Finsler became a self-taught photographer, initially taking still lifes and developing his own aesthetic within the New Objectivity. In 1927 the chocolate company Most in Halle commissioned him to photograph its factory and manufacturing processes, and these images became part of the FiFo (Film und Foto) touring exhibition in 1929. He later became director of the photography course at the Kunstgewerbeschule Zürich, where he taught for nearly 26 years.