Leaf made her first film, Sand, or Peter and the Wolf, in 1968 at Harvard University. The short was made by dumping sand on a light box and manipulating the textures frame-by-frame.
Her second film, Orfeo (1972), had her painting directly on glass under the camera. Later that year she was invited to join the National Film Board of Canada's English Animation Studio.
She mixed paint with glycerine to produce The Street, adapted from the short story of the same name by Mordechai Richler, which was nominated for an Academy Award in 1976.
From 1981 until 1986 she worked on various live action documentary films. In 1986 she produced her first animation in nearly a decade by scratching on 70mm color film and reshooting it on 35mm. "Two Sisters" (1990) won the award for best short film at the Annecy Animated Film Festival in 1991.
She worked as an animator/director at the NFB until 1991.
