Photographer Julius Theodore Boysen was born in San Francisco, California on 28 December 1868 to Julius Boysen and Albina Lundstrom. At the age twenty-one, the junior Julius Boysen went to work on various ranches and farms in the Sierra foothills, living with a relative in Cooperstown. After about six years he moved to Yosemite Valley to work as a trail builder. While there, Boysen met photographer Arthur Pillsbury who taught him the methods for developing and finishing film. Together, they founded a small photography developing business in 1897, which primarily served tourists visiting the Yosemite Valley.

The following year, Boysen bought out Pillsbury's share and established his own business, working first in a large canvas tent before building a proper wooden structure for the studio a few years later. Besides selling curios, Boysen took portraits, sold camera equipment, and processed film for locals and tourists alike. In 1900, he married San Francisco teacher Mabel Sweetland and she worked as his assistant, as well as a professional photo-tinter. By the 1910s their business was so popular they began receiving film to develop and finish from customers as far away as Scotland and colonial Africa.

Boysen also made a reputation for himself as a landscape photographer and amateur botanist, focusing on ferns of the Yosemite Valley. He and his wife established friendships with many indigenous people of the valley, including Paiute families who would allow Boysen to photograph them in their daily routines, rather than posed. His most well-recognized image is of Paiute woman Suzie McGowan with her baby, Sadie, strapped to her back in a traditional beaded cradleboard.

Boysen’s failing health in the 1920s caused him put his business up for sale. Several failed attempts later, Boysen transferred the business to his wife’s name. Mabel took Julius to a sanitorium in Sacramento, California in 1936 where he died on May 29, 1939. Mabel Boysen ran the business until her sudden death on 10 May 1943. Their daughter Ellen sold everything to Yosemite Park and Curry Company in August 1943.