Question: Which film director, Frank Pierson or Peter Tscherkassky, primarily used a darkroom rather than digital film to produce their works?

full_context: Document 1: Frank Capra: Frank Russell Capra (born Francesco Rosario Capra; May 18, 1897September 3, 1991) was an Italian-American film director, producer and writer who became the creative force behind some of the major award-winning films of the 1930s and 1940s. Born in Italy and raised in Los Angeles from the age of five, his rags-to-riches story has led film historians such as Ian Freer to consider him the "American dream personified."
Document 2: Ron Fricke: Ron Fricke is a North American film director and cinematographer, specializing in time-lapse photography and large format cinematography. He was the director of photography for "Koyaanisqatsi" (1982) and directed the purely cinematic non-verbal non-narrative feature "Baraka" (1992). He designed and used his own 65
Document 3: Found footage (film technique): Found footage is a subgenre in films in which all or a substantial part of a fictional film is presented as if it were discovered film or video recordings. The events on screen are typically seen through the camera of one or more of the characters involved, often accompanied by their real-time off-camera commentary. For added realism, the cinematography may be done by the actors themselves as they perform, and shaky camera work and naturalistic acting are routinely employed. The footage may be presented as if it were "raw" and complete, or as if it had been edited into a narrative by those who "found" it.
Document 4: Frank Darabont: Frank Árpád Darabont (born Darabont Ferenc Árpád; January 28, 1959) is a French-Hungarian-American film director, screenwriter and producer who has been nominated for three Academy Awards and a Golden Globe Award. In his early career he was primarily a screenwriter for horror films such as "", "The Blob" and "The Fly II". As a director he is known for his film adaptations of Stephen King novellas and novels such as "The Shawshank Redemption", "The Green Mile", and "The Mist".
Document 5: Peter Zeitlinger: Peter Zeitlinger A.S.C. (born 6 June 1960 in Prague) is an Czechoslovakian-born Austrian cinematographer, who has worked with the director Werner Herzog since 1995. Their film "Encounters at the End of the World" was nominated for the Academy Award 2009. Peter Zeitlinger studied from 1980 - 1987 at the University of Music and Performing Arts, Vienna. He was influenced by Michael Snow and Peter Kubelka followed by Vittorio Storaro, Sven Nykvist and Vilmos Zsigmond. Zeitlinger's films have received considerable critical acclaim and achieved popularity on the art house circuit.
Document 6: Peter Watkins: Peter Watkins (born 29 October 1935) is an English film and television director. He was born in Norbiton, Surrey, lived in Sweden, Canada and Lithuania for many years, and now lives in France. He is one of the pioneers of docudrama. His films present pacifist and radical ideas in a nontraditional style. He mainly concentrates his works and ideas around the mass media and our relation/participation to a movie or television documentary.
Document 7: Peter Tscherkassky: Peter Tscherkassky (born October 3, 1958) is an Austrian avant-garde filmmaker who works primarily with found footage. All of his work is done with film and heavily edited in the darkroom, rather than relying on recent advances in digital film.
Document 8: Peter Szewczyk: Peter Szewczyk is an American film and animation director, cinematographer and music video director.
Document 9: Frank Schaeffer: Frank Schaeffer (born August 3, 1952) is an American author, film director, screenwriter, and public speaker. He is the son of the late theologian and author Francis Schaeffer. He became a Hollywood film director and author, writing several internationally acclaimed novels depicting life in a strict evangelical household including "Portofino", "Zermatt", and "Saving Grandma".
Document 10: Frank D. Gilroy: Frank Daniel Gilroy (October 13, 1925 – September 12, 2015) was an American playwright, screenwriter, and film producer and director. He received the Tony Award for Best Play and the Pulitzer Prize for Drama for his play "The Subject Was Roses" in 1965.
Document 11: Frank Pierson: Frank Romer Pierson (May 12, 1925 – July 22, 2012) was an American screenwriter and film director.
Document 12: John Frankenheimer: John Michael Frankenheimer (February 19, 1930 – July 6, 2002) was an American film and television director known for social dramas and action/suspense films. Among his credits were "Birdman of Alcatraz" (1962), "The Manchurian Candidate" (1962), "Seven Days in May" (1964), "The Train" (1964), "Seconds" (1966), "Grand Prix" (1966), "French Connection II" (1975), "Black Sunday" (1977), and "Ronin" (1998).
Document 13: Cinema of Ukraine: Ukraine has had an influence on the history of the cinema. Prominent Ukrainian directors include Oleksandr Dovzhenko, Dzyha Vertov and Serhiy Paradzhanov. Dovzhenko is often cited as one of the most important early Soviet filmmakers, as well as being a pioneer of Soviet montage theory and founding Dovzhenko Film Studios. In 1927 Dziga Vertov moved from Moscow to Ukraine. At the film studio VUFKU he made several avant-garde documentaries, among them «The Eleventh Year», «Man with a Movie Camera» and first Ukrainian documentary sound film «Enthusiasm (Symphony of the Donbass)». Paradzhanov was an Armenian film director and artist who made significant contributions to Ukrainian, Armenian and Georgian cinema; he invented his own cinematic style, Ukrainian poetic cinema, which was totally out of step with the guiding principles of socialist realism.
Document 14: Frank Daniel: František "Frank" Daniel (April 14, 1926 – March 29, 1996) was a film director, producer and screenwriter born in Kolín, Czechoslovakia (the present day Czech Republic). He is known for developing the sequence paradigm of screenwriting.
Document 15: Stan Brakhage filmography: Over the course of more than five decades, the American experimental filmmaker Stan Brakhage produced a large body of work. All films in the filmography are assumed to be silent, in color, and are meant to be shown at 24 frames per second, unless otherwise noted. The Brakhage films, comprising his edited originals, intermediate elements, and other original material, are housed at the Academy of Motion Picture Arts and Sciences Film Archive, where a long-term project is underway to preserve and restore his entire film output.
ground_truth: Peter Tscherkassky