After rear projection was deemed impossible and conventional front projection "a non-starter" because of shadows, staff at a Cambridge school have hit on a solution for their assembly room.
Students at King's College School can now enjoy DVDs projected onto the hall's stage back-wall - and scenic Powerpoint images behind them during their performances - thanks to skilful mirror assembly and a ceiling-mounted 5000 ANSI lumens Sanyo LCD projector.
Because the back wall of the stage is concrete, staff concluded rear projection was not the way to project large-format images onto it. With front projection also ruled out on account of the shadow problem, audio visual integrators were summoned to assess the situation.
"Having taken measurements of the stage area and the space above, we were able to determine whether it was possible to install a mirror and projector rig into the available space," said Paul Mayhew from Digital Vision AV tells Lighting & Sound International.
He explains that the beam from the overhead Sanyo LCD projector, fitted with a short-throw lens, is now folded off a 1.1m mirror foil, tilted at an 11-degree angle, to create sharp images on the wall, which was treated with projection screen paint beforehand.