Sommer opened his first photography studio in Switzerland, where he made relief images of mountains for the Swiss government.

Operating from their respective Naples and Rome studios, Sommer and Behles became one of the largest and most prolific photography concerns in Italy.

[2] Most notably, Sommer published his comprehensive album Dintorni di Napoli, which contained over one hundred images of everyday scenes in Naples.

Sommer and Behles exhibited extensively and earned numerous honors and prizes for their work (London 1862, Paris 1867, Vienna 1873, Nuremberg 1885).

Sommer worked in all the popular formats of his day: carte de visite, stereoview, and large albumen prints (approximately 8 × 10) which were sold individually and in bound albums.