He received a Bachelor of Fine Arts from Syracuse University in the School of Art and his Master of Arts from Syracuse University in the School of Communications.
He is known for his landscape photography such as his 1974 "Altered Landscapes" series. He taught at the Rochester Institute of Technology, Rochester, New York, from 1968 – 1983. Later he was professor at the University of New Mexico, Albuquerque.
Presently (2012) he teaches at the University at Buffalo, The State University of New New York
Pfahl has appeared in over 100 group and solo exhibitions, and his work is represented in at least forty-five public and corporate collections, including the George Eastman House International Museum of Photography, the Cleveland Museum of Art, and the Art Institute of Chicago.