She is perhaps best known for her photograph, Imogen and Twinka, featuring an elderly Imogen Cunningham encountering Twinka Thiebaud nude, in the woods. Dater was born in 1941, in Hollywood. She grew up in Los Angeles, and studied art there, before moving to San Francisco to take a photography course with Jack Welpott, whom she later married. In 1975, they published a joint work, titled Women and Other Visions. In 1964, Dater met Imogen Cunningham, whose life and work had greatly inspired her. In 1979, three years after Cunningham's death, she published Imogen Cunningham: A Portrait, containing interviews with many of Cunningham's contemporaries, and photos by both Dater and Cunningham.