increased bandwidth available to control increasingly complicated effects. Using the new Ethernet technology, control surfaces are now able to control a much larger array of automated fixtures. The most recent development in lighting control is RDM (lighting), or Remote Device Management. This protocol allows for communication between the lighting controller and fixtures. With RDM, users can troubleshoot, address, configure, and identify fixtures from the RDM enabled lighting desk. Moving lights are much more difficult to program than their conventional cousins because they have more attributes per fixture that must be controlled. A simple conventional lighting fixture uses only one channel of control per unit: intensity. Everything else that the light must do is pre-set by human hands (colour, position, focus, etc.) An automated lighting fixture can have as many as 30 of these control channels. A slew of products are available on the market to allow operators and programmers to easily control all of these channels on multiple fixtures. Lighting boards are still the most common control mechanism, but many programmers use computer software to do the job. Software is now available that provides a rendered preview of the output produced by the rig once fixtures are connected to the program or console. This allows programmers to work on their show before ever entering the theater and know what to expect when the lights are connected to their controller. These products usually feature some method of converting a computer's USB output to a DMX output. Construction Intelligent fixtures usually employ compact arc lamps as light sources. They use servo motors or, more commonly, stepper motors connected to mechanical and optical internal devices to manipulate the light before it emerges from the fixture's front lens. Examples of such internal devices are: Mechanical dimming shutters used to vary the intensity of the light output. Mechanical dimmers are usually a specially designed disk or a mechanical shutter. Shutters with high speed stepper motors can be used to create strobe effects. Color wheels with dichroic color filters used to change the color of the beam. Variable, incremental Cyan, Magenta and Yellow color-mixing filters to vary beam color via subtractive color mixing. Using this method, a much wider range of colors can be created than is possible using single color filters. Automated lens trains used to zoom and focus the beam; irises are used to change the size of the beam. Some fixtures have as