Rear projection

In rear projection the projector sits behind the screen and throws forward through a translucent surface. From the audience side the image looks the same as front projection; what changes is everything happening in front of the screen.

The reason to use it is shadows. In front projection, anyone who steps between the projector and the screen casts a shadow across the image and gets a slide projected onto their face. On a stage where presenters move, or where an award is handed over in front of the screen, that is not a risk — it is a certainty.

What it costs is depth. The projector needs throw distance behind the screen, and that space has to be masked so the audience sees a screen rather than a room. In a venue without the depth, a mirror can fold the throw back on itself and buy some of it back, at the cost of a more finicky alignment.

The practical decision is usually made at the site survey by measuring what is actually behind the screen position. A ballroom with a service corridor behind the head table has the depth. A room where the screen goes against a wall does not.

AV rental — owned inventory, our own crew, and a site survey before anything is specified.

• Fast-fold screen A large projection screen on a folding frame that assembles on site, dressed with skirting and available for front or rear projection.
• Projection mapping Projecting onto something that is not a flat white screen — a building, a set piece, a staircase — with the image built to fit that exact surface.
• LED wall A screen built from modular LED panels bolted together, bright enough to read in daylight and sized to the room rather than to a projector lens.