Leopold Detoni was an amateur photographer, photojournalist and from 1922 at the latest owner of Fotofachverlag Josef Detoni in Vienna. In 1916 he joined the Photographische Gesellschaft in Vienna, worked as a journalist, including for the Österreichische illustrierte Zeitung, and in 1919 founded the Allgemeine Photographische Zeitung, which in 1923 became the official mouthpiece of the Österreichischer Photographen-Verein and in the 1920s was the most prominent trade journal for Austrian professional photographers, federal and provincial professional associations and the Verband der Photographengenossenschaften Österreichs. Detoni was the publisher, editor-in-chief and from 1929 proprietor of this magazine, which was incorporated in 1943 in the Photographische Chronik published by Verlag Wilhelm Knapp in Halle an der Saale and was to continue as the Photographische Chronik und Allgemeine photographische Zeitung as the mouthpiece of the Reichsinnungsverband des Fotografengewerbes until 1945. In the April 1938 edition of the Allgemeine Photographische Zeitung he enthusiastically welcomed the annexation of Austria to Nazi Germany and urged photographers to vote in the plebiscite on 10 April 1948 for the "Führer and saviour of the greater German nation". At the same time, he distanced himself from the era of Austrofascism, which he criticized as promoting "degenerate statecraft" He hoped that the National Socialist regime would put an end to the "liberalist era" and would implement protectionist measures in favour of "Aryan" photographers, at the same time condemning the previously damaging effect of "ethnically alien" (volksfremd) elements in the trade. In 1940 he stated in an application for admission to the Reichsschrifttumskammer (Reich Literature Chamber) that he had applied to join the Party in January 1938 and became a member of the NSV (National Socialist People's Welfare) in July 1938. After 1940 he advocated close collaboration between the Fotografenzunft (professional association of photographers) and the National Library and called for the negative photo plates to be given to it for its picture archive. Until 1941, he presented monthly lists In the trade magazine published by him of Aryanized photography businesses including the names of their former owners. After the annexation, he rose in professional bodies and in 1938 became secretary of the Ostmark section of the Fotografenzunft and of its master Egon Jelinek. In this position he was also in involved in the Aryanization of Jewish photography businesses controlled by the association and was an important member of the Arisierungskommission. As assessor for the Vermögensverkehrsstelle (Property Transaction Office) he wrote at least six expert opinions in summer and autumn 1938 on studios and commercial photography businesses, including those belonging to Otto Johannes Benedikt, Baruch Kern, Arnold Schalita, Gisela Selka and Oskar Weitzmann. He was also involved in 1938 in the house search of apartment of Wilhelm Pollak. After the war and until his death in 1946 he attempted to rebuild the professional photographers' organization. His publishing company was continued by his wife after the war.

From the project Durch das NS-Regime aus Österreich vertriebene und ermordete Fotografinnen und Fotografen und der Verbleib ihrer fotografischen Sammlungen (Subsidized by the National Fund of the Republic of Austria. Conducted by Walter Mentzel).