At age 23, Hahn graduated with a B.A. and continued at Indiana University for graduate studies with Henry Holmes Smith in the department of photography. At his suggestion she started experimenting with the gum bichromate process. Smith convinced Hahn that photography was serious, potent stuff, and she eventually settled into the comfortable but exciting dialogue with photography, which would characterize her career. Working under Smith, she met Robert Fichter, who became the subject of some of her early photographic projects and an important influence.
In 1967, Hahn moved to Rochester to pursue a job at Kodak or Xerox. While in Rochester, she participated in Nathan Lyons’s evening workshop from 1967 to 1968. Lyons lectured on “vernacular” and “snap shot” photography to workshop students, reinforcing Hahn's interest in this “folk” tradition. During her time in Rochester she met Joan Lyons, Jim Borcoman, Tom Barrow, Roger Mertin, Bea Nettles, and Alice Wells, and reconnected with Robert Fichter. She was interested in how their work was challenging the rules of what was common in fine-print photography.
Hahn began teaching photography and design to deaf students at the National Technical Institute for the Deaf, which was newly opened and partenered with Rochester Institute of Technology. After one year, she transferred to the School of Photographic Arts and Sciences, where she taught until 1975.
Hahn met Lee Witkin at a reception at the George Eastman House in Rochester, N.Y., in 1972. Her first one-person show, “Betty Hahn,” opened in New York City at the Witkin Gallery in 1973. In 1974, she received a grant from the National Endowment for the Arts to be a visiting artist at Franconia College in New Hampshire to continue projects in non-silver processes and mixed media.
At the age of 35, Hahn was hired as a visiting professor to teach photography at the University of New Mexico in Albuquerque and became permanent faculty in 1976. In 1978 and 1983, she received grants from the National Endowment for the Arts for ongoing projects. During the spring semester in 1986, she became full professor of photography. She taught there until retirement in 1997.
Among the many museum collections that contain Hahn’s work are the Art Institute of Chicago; the Museum of Modern Art, New York; the National Gallery, Ottawa; and the San Francisco Museum of Modern Art.