Born in Hadersdorf am Kamp, Austria in 1938, died 1988 in Vienna. Attended Vienna´s Film Academy for 2 1/2 years, leaving in 1963 when a film project proposal was denied (which later became his second film P.R.A.T.E.R.). After 1963 numerous 16mm films. Couuntless screenings, including Experimental Film Festival Knokke, Berlin Film Festival, Centre Pompidou, Paris, art fair Basel and the Viennale. Editor of the hectographed film journal Caligari (2 issues) in 1964 partly in collaboration with Hans Scheugl and Peter Weibel.
As of 1966 he contributed to film journals in West Germany, Austria, Switzerland (e.g. Film, Kino, Kinema, Supervisuell, Blimp); writing articles about Sergej Eisenstein, Kurt Kren, Erich von Stroheim, G.W. Pabst et al.
Co-founder of the Austria Filmmakers Cooperative in 1968 (together with Hans Scheugl, Valie Export, Peter Weibel, Kurt Kren, Gottfried Schlemmer). Schmidt jr. wrote the first encyclopedia of new European avant-garde und aunderground film, Das andere Kino (in the Film 1968 yearbook). Together with Hans Scheugl he wrote the most comprehensive book about avant-garde Eine Subgeschichte des Films (two volumes, Frankfurt am Main, Suhrkamp) in 1974.
In 1976 he completed his first full-lenght film , Wienfilm 1896-1976 in collaboration with Joe Berger, Ernst Jandl, Gerhard Rühm, Peter Weibel, Friedrich Achleitner, Padhi Frieberger et al.
In 1980 he edited the catalogue Österreichischer Avantgarde und Underground Film 1950-1980 for the Austrian Film Archive on the occasion of a retrospective at the Z-Club Alternativ. In 1981 he realized his second feature Die totale Familie based on a novel by Heimito von Doderer. From 1986 to 1988 he worked on a filmic adaption oft he book Denkwürdigkeiten eines Nervenkranken by Daniel Paul Schreber, which took the form of a three-part compilation film.
He died during the completion of part two, on February 9, 1988. His assistant Susi Praglowski completed part two; part three realized by Peter Tscherkassky in 1993.