Johanna (Tanna) Hoernes was born in Graz, Austria. She studied at the School for Women and Girls with Ludwig Michalek and at the Vienna Academy of Art with Wilhelm Unger, where she met her future husband, Luigi Kasimir. They were married in 1911 and worked collaboratively to develop the revolutionary technique of color etching. Each produced a substantial body of work, consisting largely of views based on their worlwide travels. Her work is highly prized for its exacting detail and realistic depiction of both the notable architectural subjects and natural landscapes that she and her husband observed in their travels.