The Lamphouse and Projector

The Lamphouse and projector is the front-end for all the pretty pictures we show you in Bowland LT. It consists of a Century C series 35mm Turret Projector attached to a ORC Orcon II Lamphouse. This very unflatteringly translates as a big whirly motor bit attached to a box with a light bulb in it.

Our projector handles industry standard 35mm film in both Widescreen (1.85:1) and Cinemascope (2.35:1) formats. This is accomplished by having two lenses mounted on the projector which can be changed between in about a second.

The lamps we use aren't your standard 100watt bulbs from B&Q. We use Osram XBO 1600watt Xenon Arc Lamps. Unlike a normal light bulb, they don't have a wire which glows, but rely on an arc of electricity passing between an anode and a cathode. This is all done in a quartz glass envelope filled with pure xenon gas. An initial potential of around 60,000v is needed to spark the lamp and a stable supply of around 20v and 60a is needed to keep the lamp lit, which all ads up to a hell of a lot of power. All this making-electricity-jump-across-gaps produces a lot of heat and pressure and the lamp runs at about 200C. At the end of the day, all that trouble's worth it for the light it produces, which is so bright and intensely white that direct exposure to the lamp would more than likely blind the onlooker - bad for those foolish enough to look at the lamp, but perfect for cinema!

This light is then shined through film in order to project a picture onto the screen. Even that's more complicated than it sounds! In order to produce a non-blurred image, each frame of film has to be stopped in front of the light path, shown twice, then moved on to the next frame. As a result, the sprocket moving the film has to stop and start 24 times each second. To complicate things even more, to make the image even smoother on the screen, the light source needs to be interrupted between each frame. This means that a special shutter has to cut off the light path before it passes through the film 48 times each second! This renders an image being stopped and started so fast that our feeble human brains can't notice and the end result is a smooth picture on the cinema screen!

So there you go - A fancy lightbulb in a box, but our Projector is one of the most precision pieces of engineering out there and without it LU Cinema would not exist

Last edited by Stuart Clarkson (2005-11-21 14:56:49)