Theobald studied at School of the Art Institute of Chicago, earning a BFA in 1968 and MFA in 1971. He received the Logan Prize in the 1968 Chicago and Vicinity Show at Art Institute of Chicago and the Slobe Award in 1973. Trained in painting, he has spent the past 10 years doing large scale photographs, having over 20 solo exhibits in that time. In 1990 he was invited to work with the Russian Ministry of Culture and has made 16 trips back to Moscow where he has worked with numerous artists and the Tretyakov Museum. Many of his recent works are Russian landscapes, which complement his American landscapes. The National Trust has recently published his photographs of the Farnsworth House.