While working at the local Herdorf iron-ore mine, Sander first learned about photography by assisting a photographer from
Siegen who was also working for the mining company. In the early 1920s, he came in contact with the
Cologne Progressives, a radical group of artists linked to the
workers' movement, which, as
Wieland Schmied put it, "sought to combine
constructivism and
objectivity,
geometry and object, the general and the particular, avant-garde conviction and political engagement, and which perhaps approximated most to the forward looking of
New Objectivity [...] ". In 1927, Sander and writer Ludwig Mathar travelled through
Sardinia for three months, In 1953, Sander sold a portfolio of 408 photographs of Cologne, taken between 1920 and 1939, to the
Kölnisches Stadtmuseum. These would be posthumously published in book format in 1988, under the title
Köln wie es war (Cologne as it was). In 1962, 80 photographs from the
People of the 20th Century project were published in book format, under the name
Deutschenspiegel. Menschen des 20. Jahrhunderts (German Mirror. People of the 20th Century). ==Personal life and death==