In his book Documentary Film Paul Rotha indentifies four documentary traditions:

The Naturalist (Romantic) Tradition

This tradition draws on the observation of life being lived in its own natural environment. It involves the filmmaker learning about that life and its customs, much as an ethnographer does while in the field. But this tradition is more than just recording; the assembling of images into a final cut requires close understanding and interpretation. Rotha cites Robert Flaherty’s Nanook of the North (1922) and Moana (1926) as examples of this tradition.

The Realist (Continental) Tradition

The realist tradition is rooted in the French avant-garde that celebrated art for art’s sake. While the naturalist tradition was grounded in nature, this tradition attempted to capture the modern world, within cities in particular. Rotha names Alberto Cavalcanti’s Nothing But Time (Rien que les heures, 1926) as an example of this tradition. The film is about a day in Paris city life. Cavalcanti’s film was released before Walter Ruttmann’s Berlin: Symphony of a Great City (1927). Other examples include Joris Ivens’s Rain (1929) and The Bridge (1928).

The Newsreel Tradition

The newsreel provides a brief overview of everyday events. Economy and clarity are the clearer goals of newsreel, but some newsreels can be elevated to what he calls the level of reportage. Rotha refers to the Kino-Eye theories and practices of Dziga Vertov, who uses the language of cinema to present life from all sides by bringing order to the chaos of modern life. Rotha qualifies this tradtion with the critique that it fails to get below the surface of the image. He cites Man with a Movie Camera (1929) as an example of this tradition.

The Propagandist Tradition

Elements of persuasion occur in a variety of filmmaking traditions, and documentary is no exception. Rotha explores how this propaganda tradition occurs in both the Soviet Union and England. The purposes of Soviet propaganda were to support the new union, to explain new social beliefs, and to motivate the masses to support them. Rotha cites Sergei Eisenstein’s October (1927) as one example. In Britain the desired intentions were more gradual and less overt. The British films gave a human face to the working class, showing its members as skilled and showing their contributions as vital to society. Rotha cites John Grierson’s Drifters (1929) as an example.

Source: Rotha, Paul, with Sinclair Road and Richard Griffith. Documentary Film. New York: Hastings House, 1953. [Originally London: Faber and Faber, 1935]. 75-100.