A.C. Warner was a staff photographer for the Northern Pacific Railway when he first came to Washington Territory. Born in Massachusetts in 1864, his youth had been spent in Minnesota where he studied photography and found the job that took him to the Far West in 1886. In Seattle, Warner soon formed a short-lived partnership with one Davis, working jointly to make and sell some fairly conventional views of Seattle, the ships on Elliott Bay, and the mills along the waterfront. In 1888, he was engaged by John Muir to join a Mount Rainier climbing expedition. His personal account of the first historic use of the camera on the upper slopes and at the summit of the mountain was published in (1956).

After Warner married Edith Randolph, the daughter of the well-to-do Captain Simon Peter Randolph, he formed a business partnership with his father-in-law. S.P. Randolph may have furnished the necessary capital and Warner the essential camera and legwork for an adventure in Gold Rush photography in Alaska. In the summers of 1898, 1899 and 1900, Warner went to Alaska as a prospector, a packer and a photographer. The cartouche on the reverse of his Alaskan cabinet mounts provides a Seattle address and gives an indication that the Alaskan specialty of Warner was in views of Skagway, Dyea and the Chilkoot Pass.

After 1900, Warner remained in Seattle to pursue several lines of work - as a photographer for the publisher Lowman and Hanford, as a confectioner with a shop in the Seattle Hotel on Second Ave., and as a sales agent for the landscape paintings and photographs of Albert Henry Barnes of Tacoma who died in 1920. After Barnes death, Warner became more active in his own photographic enterprises, continuing until his death in 1943. In 1925 he commenced the Warner Projection Company and found a ready market for art deco projection slides to be used with cartoons and the lyrics of popular songs which might be projected on the theater screen. In addition, together with his wife, Warner presented illustrated lectures on the wild flowers of western Washington.