• Number of dimmed circuits required.  We always attempt to maximize flexibility.  This has usually meant more circuits in more locations.  This is based on an assumption that all or most of the lighting being used is halogen incandescent and requires a dimmer to be controlled.  LED fixtures are rapidly improving, catching up or surpassing their “conventional” counterparts.  This is especially true for cyclorama and back drop lighting, an area that has typically required a fair quantity of 1,000 watt fixtures ganged together.  Now we see LED color changing fixtures that actually out perform the conventional fixtures.  Although on the surface they are more costly, it’s worth noting that the LED fixtures don’t require on-going lamp changes and use much less power–and don’t need 3-4 dimmers each.  We saw at LDI (Lighting Dimensions International) last year LED-based ellipsoidal spotlights.  They weren’t ready for “prime time” yet, but they do have the major features required in a fixture of this type–hard edges, ability to be shuttered and the ability to project patterns.  Moving fixtures are showing up more and more frequently in all types of venues.  If planned for carefully, these are able to replace 2-3 conventional fixtures each.  Finally, tried and true color scrollers, changers and faders are allowing one fixture to do the job of several.  All of these lead in a direction of allowing fewer dimmed circuits to do the same, or more.  There is a need for more non-dimmed power, on the other hand, but this is typically far less expensive.  This also means that the data network and controller has to be more ubiquitous, flexible and powerful than ever before.
• Amount of “diversity” assumed.  We’ve typically allowed that the 2.4kW dimmed circuits in a theatrical system will not ever be loaded to more that 50% of their OVERALL capacity–meaning some may carry a full 20 amp load while others carry none.  This assumes, however, an average lamp size of approximately 1,000 Watts.  Looking at the fixtures commonly available at present, many conventional fixtures are actually capable of a maximum 575 Watts or 750 Watts.  This has been made possible by advances in optical technology and design.  It may be that we’ll be able to assume a much lower overall load on the dimming system–750 Watts on average instead of 1,000 Watts per circuit.  This translates to smaller power feeds into the dimming system.

The day when we have a fully functional theater facility with only a few, or even no, actual dimmers is not inconceivable.  Already there are several commercial lighting manufacturers that have LED equivalents to the 250 Watt downlight.  And these are fully dimmable without the use of a traditional line-voltage dimmer.  LED ellipsoidal spotlights are already out and being improved.  LED PARs exist and are rapidly improving.  LED cyclorama fixtures have already surpassed their traditional predecessors.

Here are the answers to the questions we submitted (the organizers of the show chose to use the light source technologies question).

Four options to support and access performance lighting in front of the proscenium include catwalks, tension grids, dead-hung battens and battens (pipes) on some type of hoist or lowering system.

• A catwalk (or lighting platform–this is NOT your classic catwalk as the railings are intended and spaced to support lighting functions) allows easy access to fixtures but must be carefully placed to be effective.  Too close and the light will be aiming almost straight down, causing heavy shadows particularly in the eyes.  Too far, and the lighting becomes very flat and uninteresting.
• Tension grid, which is a woven steel cable mesh, provides the greatest flexibility.  Lights are above the mesh and shine through onto the stage below.  The mesh does not affect lighting (or sound) going through it with one exception: PAR fixtures.  The beam of light is parallel enough to project the image of the mesh to the surface below.  Lights can be used anywhere above the surface as needed.  The cost is about the same, per square foot, as catwalk while weighing less.  It is also possible to rig through tension grid.
• Dead-hung battens are surprisingly common and about as inconvenient as possible.  This is also the least expensive, initially, of the available options, as it is nothing but a pipe suspended from chain, cable or threaded rod directly from the structure above.  Like catwalks, these must be carefully placed to be effective.  Access for maintenance and focusing is ideally from a lift (although seats frequently interfere) or from a ladder, if low enough.
• Hoists for this application come in many flavors, each of which has its strengths and weaknesses.  Lineshaft winches, dead-haul drum winches, package hoists, self-climbing trusses, trusses with chain motors, counterweight assisted winches are just some of the options.  There are also manually-cranked winches and other variations.  The major weakness, other than placement, is that focus (aiming) of the lights will take extra time as the hoist has to be raised and lowered repeatedly to focus the lights by trial and error.

Next up are the three most common stage rigging technologies being installed in current theaters, churches and auditoriums.  Those are manual counterweight, powered hoists and dead-hung.  What is appropriate for a given stage and application varies with the space, the users and the intended uses of the system.

• Manual counterweight systems operate by balancing the load (lighting or scenery, typically) with steel counterweights.  There are variations even within this type of system (single purchase, double purchase, motor assisted, etc.)
• Powered rigging systems are most commonly seen in the form of package hoist systems.  These are standardized zero fleet-angle winches that operate on a common backbone (power and control) and usually have a common control point that often allows grouping and presets.  Other types include lineshaft winches and dead-haul winches.
• Dead hung rigging includes any rigging suspended in a static manner from the structure above.  Some examples are studio pipe grids and curtain tracks that do not fly.

The two dominant lighting source technologies at the present in the theater world are tungsten-halogen and LED.  Fluorescent is used heavily in TV studio applications.  LED technology is rapidly evolving and quickly gaining ground on traditional halogen sources.  Already, LED cyclorama lighting fixtures outperform their conventional counterparts–at least when the rich colors typically used on a cyc are involved.

Finally, the role of a theater design consultant.  Primarily, the design consultant’s role is to provide options to the design team.  Once the function of the facility and its primary program functions have been determined, HOW to accomplish those goals becomes the next puzzle.  In presentation environments, there are many ways to accomplish the same end–and each has its own strengths and weaknesses.  What is right for one user may not be appropriate at all for another.