Moving Head also known as a Yoke, is an intelligent lighting fixture, that allows the operator to position the projected beam near enough anywhere on stage. It consists of a base that has an arm on top of it. This base contains a motor that can turn (pan) the arm by at least 360 degrees. The arm holds the light and also contains a motor that can rotate (tilt) the light by at least 180 degrees. Most moving heads use a 16 bit pan/tilt system for very accurate positioning.
There are two main types of moving head, a spot and a wash.
The spot type of moving head will contain at least one gobo wheel and at least one color wheel to project a variety of shapes and colours. The wash type of moving head does not contain a gobo wheel but will have at least one colour wheel and usually a CMY colour wheel.
Most moving heads have a fulling dimming system unlike most scanners.
Some have auto focus control others have this but done via DMX signals from the console, others only have a manual focusing system.
Various other effects are put into moving head fixtures to created a multitude of different lighting effects, such as iris, strobing, prisms and beam shaping.
Depending on the manufacture and the fixture, bulbs fitted to moving heads will range from 150watt to 1500watt.
Moving heads are not as fast to move as scanners are but their versitilty out performs them in many ways.
A new range of moving heads are now starting to appear on the market that use high powered LEDs.
Examples of moving heads can be seen below, the first two are spots and the third is a wash. As you can see size and shape even from the same manufacturer varies a great deal.