Domestic competition, however, eclipsed Phonofilm. By September 1925, De Forest and Case's working arrangement had fallen through. The following July, Case joined Fox Film , Hollywood's third largest studio , to found the Fox-Case Corporation. The system developed by Case and his assistant, Earl Sponable, given the name Movietone , thus became the first viable sound-on-film technology controlled by a Hollywood movie studio. The following year, Fox purchased the North American rights to the Tri-Ergon system, though the company found it inferior to Movietone and virtually impossible to integrate the two different systems to advantage.  In 1927, as well, Fox retained the services of Freeman Owens, who had particular expertise in constructing cameras for synch-sound film.