Question: Stan Brakhage and Frank Powell are known for what kind of films?

Context paragraphs:
Stan Brakhage: James Stanley Brakhage ( ; January 14, 1933 – March 9, 2003), better known as Stan Brakhage, was an American non-narrative filmmaker.  He is considered to be one of the most important figures in 20th-century experimental film.

Frank Powell: Frank E. Powell was a stage and silent film actor, screenwriter, and director in the United States.  He was born in Hamilton, Ontario, Canada.

Interim (film): Interim is a 1953 American short film drama directed by Stan Brakhage.  It was the first film directed by Stan Brakhage, whose expansive filmography has made him an influential figure in experimental film.

Unglassed Windows Cast a Terrible Reflection: Unglassed Windows Cast a Terrible Reflection is a 1953 American short film directed by Stan Brakhage, which was made at the beginning of his long career.  Shot while Brakhage's native Denver, the film stars Larry Jordan (credited as Lawrence Jordan) who later went on to become a film director.  Filming was done in Nevadaville, Colorado.  Like his other films at the time, it was shot on 16mm film, is black and white and features no dialogue.

Window Water Baby Moving: Window Water Baby Moving is an experimental short film by Stan Brakhage, filmed in November 1958 and released in 1959.  The film documents the birth of the director's first child, Myrrena, by his then-wife Jane Brakhage, now Jane Wodening.

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.

Arabic Numeral Series: The Arabic Numeral Series, sometimes referred to as the Arabics, is a series of 19 short 16mm films completed by the American experimental filmmaker Stan Brakhage in 1981 and 1982.  The "Arabic Numeral Series" gets its name from the fact that none of the films included in it have titles, instead opening with an arabic numeral.  Brakhage produced another cycle, the "Roman Numeral Series", whose films all have Roman numerals instead of titles, around the same time.  All of the "Arabics" are silent and are intended to be projected at 18 frames per second.

Songs (Stan Brakhage cycle): The Songs are a cycle of silent color 8mm films by the American experimental filmmaker Stan Brakhage produced from 1964 to 1969.  They are seen as one of Brakhage's major works and include the feature-length "23rd Psalm Branch", considered by some to be one of the filmmaker's masterworks and described by film historian P. Adams Sitney as "an apocalypse of imagination."  One of the filmmaker's most overtly political films, "23rd Psalm Branch" is often interpreted as being Brakhage's reaction to the Vietnam War.

Cat's Cradle (film): Cat's Cradle is an experimental short film by Stan Brakhage, produced in 1959.  The film was described by Brakhage as "sexual witchcraft involving two couples and a 'medium' cat."

Jane Wodening: Jane Wodening (born Mary Jane Collom, and formerly known as Jane Brakhage) is an American writer and the first wife of filmmaker Stan Brakhage.  The birth of their first child is the subject of the 1959 experimental short film "Window Water Baby Moving".  Wodening married Stan Brakhage in 1957 and is credited with creating scrapbooks for the Brakhage family during what is recognized as the filmmaker's most significant period of creation from the late 1950s to the mid 1960s.  The couple separated in 1987.

Supporting paragraphs: Frank Powell Stan Brakhage
Answer: silent film