In order to pay for his music studies, he worked as a ticket and program seller at the Biograf movie theater where he developed an interest in film making.
That same year, Ole Olsen established the Nordisk Film studio and hired Graatkjaer as his cameraman.
His first film was Viggo Larsen's the short The Anarchist's Mother-in Law (Anarkistens Svigermoder).
Graatkjær, who also acted the part of a hunter, was jailed for one day for participating in the film because it had been forbidden by the Ministry of State.
He became the favorite cinematographer for the director August Blom, with whom he made popular melodramas such as The White Slavery Trade (Den hvide slavehandel, 1910), At the Prison Gates (Ved Fængslets Port, 1911) and A Victim of the Mormons (Mormonens offer, 1911).