The photographer joined the Sacramento Bee in 1986. Two years later, he moved to California to focus on a landscape photography. He published the book "Yosemite, Landscape of Life" in collaboration with the Yosemite Association in 1990. A year after, he was nominated for the Pulitzer Prize for Feature Photography for his “series of photographs depicting Yosemite National Park and its visitors during the park's centennial year”.[3][4][5][6]
In 2009, Mather and journalist Joel Brinkley began working on the book Cambodia's Curse: The Modern History of a Troubled Land. They visited Cambodia again to capture the current state of the country. Beside that photojournalists' essays from Cambodia were exhibited at the University of Louisville and the Portland Museum[failed verification].[7][8]