Alcott used three f/0.70 lenses developed by Zeiss for NASA for use in the Apollo moon landings, which Kubrick discovered in his search for a lens that could film in low-light situations. The super-fast lens allowed him to shoot scenes lit with actual candlelight with an average lighting volume of only three candlepower. In fact, the film features the largest lens aperture in film history.

[ http://en.wikipedia.org/wiki/Barry_Lyndon ]