The novelist and critic Susan Sontag 's life-long addiction to photographs has resulted in a series of reflective essays written over the past six years and now collected as On Photographu. The book became a surprise bestseller in America and won the National Book Critic Circle Award for criticism. though she disclaims that it is a critical work. TO write about photography is to enquire into the changing nature of the way we perceive the world. Miss Sontag believes, and in conversation with PHILIP FRENCH she discusses some of the issues raised in her book. followed by an interlude