Pete Souza, an assistant professor of photojournalism at Ohio University’s School of Visual Communication, has been chosen to serve as the chief White House photographer when Barack Obama becomes president, on January 20, the Office of the President-Elect announced today.

“I’m honored that he asked me to do this,” Mr. Souza told The Chronicle this evening from Ohio, where he said he was filling out security-clearance forms for the Federal Bureau of Investigation. “I’m certainly aware of how historic this presidency is.”

Mr. Souza, a freelance photojournalist who began teaching at Ohio in 2007, said he was taking an indefinite leave of absence from the university but planned to return to teaching someday. “This is an opportunity that I couldn’t turn down,” he was quoted as saying in a news release from the university.”

The Massachusetts-born photographer began taking pictures of Mr. Obama in January 2005 for the Chicago Tribune, shortly after the president-elect burst onto the national stage as a freshman senator from Illinois. He has since become a prominent photographer of Mr. Obama, documenting the president-elect’s visits to seven countries­­­ — including his highly publicized trips to Kenya and South Africa­ — as well as his presidential campaign.

Mr. Souza published a book of photographs, The Rise of Barack Obama, last July.

This will not be Mr. Souza’s first White House gig. He served as an official White House photographer during the presidency of Ronald Reagan, later publishing a pair of books from that stint.

Still, he believes this time around will be much different. Mr. Obama “is a lot younger than Reagan, and … it’s a different world than it was 20, 25 years ago,” Mr. Souza said. “The challenges this president is going to be facing are a lot different from Reagan’s, and so I think the resulting photographs are going to be different.”

Mr. Souza was scheduled to fly to Washington today, but said he got held up in Ohio by paperwork related to his new job. He said he did not know exactly what to expect in the coming days. “I just hope tomorrow isn’t as crazy as today,” he said. —Steve Kolowich