Punishment Park is a 1971 film written and directed by Peter Watkins. It is a pseudo documentary of a British and West German film crew following National Guard soldiers and police as they round up a group of members of the counterculture across the desert. Punishment Park was shot in 16mm with a skeleton crew of 8 people and only 1 Eclair camera. The set was extremely minimal, using only a tent enclosed within a larger tent for the interior scenes. The rest was shot on location at the El Mirage Dry Lake in California. It took only two and a half weeks to shoot. The “newsreel” quality of the film was enhanced by desaturating the color and removing the traditional hard edge of the image through the use of Harrison diffusion filters. The production budget was only $66,000, with an additional $25,000 when the film was converted to 35mm.

-Wikipedia

Above are two excerpts from the beginning of the film: