Born in Chicago, Knopf studied at the Art Institute of Chicago under John Vanderpoel and Frederick Freer, graduating in 1900. That same year she joined the faculty of the Illinois Women’s College at Jacksonville (now MacMurray College.) She received her doctorate from the College in 1935, and continued to teach there until 1943. From 1910 to 1917 Knopf spent summers studying with Charles Woodbury in Ogunguit, Maine. She also studied with Birger Sandzen at the Broadmoor Academy.
Knopf began making summer painting trips in the West in 1921. She used two sabbaticals in 1923-1924 and 1941-1942 to visit California, Arizona, New Mexico, Wyoming, Texas and Colorado. She went to Glacier National Park during the summers of 1925 and 1926, and in later years traveled to Mexico. After retiring, Knopf moved to Lansing, Michigan and later to Eaton Rapids, Michigan.
Knopf primarily painted landscape views in oil, working in a modernist style with loose brush work. She exhibited her paintings extensively including such venues as the Corcoran Gallery, National Academy of Design, Kansas City Museum of Art, and the Detroit Institute of Arts. In 1987 MacMurray College held a major retrospective of Knopf’s work.