Ketchum received a BA in Design at the University of California at Los Angeles, studying under Teske, Fichter and Heinecken. He also attended Brooks Institute in Santa Barbara and the California Institute of the Arts in Valencia, where he completed an MFA in 1973.
Since 1979 he has been curator at the National Park Foundation in Washington, D.C., and contributing photographer for Powder Magazine. His professional experience also includes serving as a curator for the Security Pacific Bank (1979) and teaching photography at the California Institute of the Arts, Valencia (1975), and in workshops that he started at the Sun Valley Center for the Arts and Humanities in Sun Valley, Idaho (1971 - 73).
The artist, working in 35mm and 4x5, produced black-and-white prints as well as Ciba- chrome color prints.
He belongs to SPE, Friends of Photography in Carmel, the Sierra Club and the Los Angeles Center for Photographic Studies, for which he served as president in 1979.