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F

• The process by which a lighting instrument is either manually or remotely positioned to light a specific part of the stage. With conventional fixtures focus is performed after lighting equipment is hung in place and is connected to the proper circuit. Automated fixtures can be remotely focused and may have many different focuses for a particular show. Focus presets are often created as libraries of focus points for a show. Focus presets as well as conventionally focused equipment must be checked any time a show changes venues, as the relationship of lighting instrument and stage may change.
• 1. The session when all the lanterns in the rig are angled in the correct direction, with the correct beam size.
  2. Description of how sharply defined a light beam is ("give that profile a sharp focus").
  3. Control on projection equipment used to change the focus.
• Adjusting beam spread from spot to flood, or to light a specific part of an area of the stage.

FOCUS CHART
Documentation produced by the lighting designer which shows graphically the exact focus of a particular lantern in the rig. Essential for long-running shows where the crew can use it as a reference when replacing lanterns or checking focus after cleaning etc. The charts can also be used to do a "rough" focus before a lighting designer arrives at the venue. Touring shows sometimes use a floorcloth marked out with focus information to aid speedy focussing in a new venue.

FOCUS POINT
Function on some computerized lighting desks which allows the operator to specify a place on the stage to which moving lights can be made to move on cue. Once defined, the focus point can easily be recalled and used in multiple cues. If the location of that item is moved (e.g. the chair is moved to the right) all moving lights will automatically focus on the new location.

FOCUS PRESET

• Memorized focus positions stored in memory.
• A feature of some automated fixture consoles which allows libraries of memorized focus positions to be stored centrally in memory. Presets can then be accessed individually by cues to position fixtures at pre- determined locations on stage. Using focus presets is a much more efficient method for cueing automated fixtures than writing positions individually into every cue in a show.

FOCUS SPOT
Term for both Fresnel and PC type lanterns with adjustable beam size.

FOCUSING
The process of adjusting the direction and beam size of lanterns. Does not necessarily result in a "sharply focused" image.

FOG
A term used to describe a range of stage fog, haze, and smoke effects. Fog is commonly created from the heat expansion and atomization of a fog fluid in a fog machine.