Basic Lighting Instruments: Pros and Cons- Part II

In Uncategorizedby tfwm

In Part I of this series (May 2000 issue) we learned about the differences (pros and cons) between the four most commonly used theatrical instruments. At this point, we can now intelligently pick and choose the lighting instruments that would serve us best for a new lighting installation.

We will look at a “case study” in which the approach to the installation design will be determined by answering the following questions?

I. What are the basic needs for a Sunday morning/typical worship service

II. How many and what kinds of lights will meet these needs and where should the lights be hung?

III. What can be added to the design to allow flexibility for special events?

The following computer generated figures are a perspective and overhead view of a church stage illustrated with ceiling beams. The purple dots represent hooks placed in the ceiling for overhead hanging of curtains/ light bars/ scenery. The main staging area covers a space of 48′ x 25′.

Answers to questions

Basic Sunday morning or weekly worship service needs
The band and the worship team can be placed on the stage almost anywhere depending on the given week. Soloists/duets will sing occasionally on either side of the stage.

A front projection screen is positioned just behind the back beam. This screen is used for lyrics of worship songs, announcements and occasional videotape presentations. In addition, 18′ wide sets of steps (not shown) are located just in front of the stage on either side. The steps are sometimes used as risers for kids’ choirs, and a communion table is positioned between the sets of steps.

Types of lights needed and where they could be hung

Front lighting
Fortunately, the second beam back from the stage is positioned so as to create an angle that is 35-55 degrees to the stage floor. This will be an ideal place to secure a light bar. Both the center section (between the large beams perpendicular to the stage) of the beams and the side section should be utilized.

The throw of an instrument will be at least 30-40 feet, depending on where the instrument is positioned on the bar. Therefore, to give good control of the light coming from the front light bar, ellipsoidals would be the instrument of choice. Parcans and Fresnels would give off extraneous light (light leaving the instrument in unintended directions) which would likely create some wash out on the screen.

Back lighting
Back lighting is best achieved if the light creates a 60 degree angle to the stage. This is obviously achievable on some parts of the stage but not on others; i.e., at the deepest locations on the stage the light angle becomes almost 90 degrees. However, two light bars, one as deep as possible and the other about mid stage, extending the entire length of the stage should provide fairly adequate positions for back lighting.

My light of choice for this would be fresnels. Once again, I believe control is the issue. Although par cans would be adequate over much of the stage, the areas just in front of the screen would likely be washed by a par cans extraneous light. Fresnels would allow for a little more directional control of the light. In addition, fresnels allow one to manipulate and blend the light spread very easily. Par cans require the changing of the entire lamp assembly or lens to change the spread. The changed spread is from one fixed position to another, nothing in between. However, if PAR cans are what the budget allows, I would recommend using barn doors for increased light control.

Before answering the last question, lets look at a possible light plot based upon the answers to our questions so far.

The light plot, shown on the following page, is a possible graphic solution to the needs determined from our first two questions. For example, the answer to the first question shows that this church needs great flexibility in the positioning of various components for a worship service.

Except for the choir, elements of a worship service could be positioned almost anywhere on the stage. Therefore, as the plot demonstrates, instead of having an area labeled as band or worship team, etc, six lighting zones were created and can be individually highlighted (or not) for any given service.

One word of advice: In order to make the best use of this type of light design, the person setting up the stage needs to position elements within light zones. That is, a band that is primarily in zones 4 and 5 but goes beyond the boundary of 5 into 6, will either: a) be partially in the dark; b) necessitate a big area being lit where nothing exists; c) keep the element in area 6 from being independent of the band.

This plot also demonstrates that ellipsoidals are exclusively used from two bars (an upper ‘U’ and lower ‘L’) positioned at the second beam in front of the stage. Once again, this position creates an angle to stage floor of 35-55 degrees. Forty-five degrees is ideal. There are, however three different ellipsoidals as indicated by the legend and the fixture symbols. The PRO 1K M has a degree of spread that will cover approximately 12-14 feet in diameter of stage area. Therefore, you know that you will likely need 4 lights coming from each direction to cover zones 1-4. Since the stage narrows towards the back (zones 5-7), 3 lights, or 36′ of coverage, from each direction will be sufficient.

The PRO 1K W have a larger degree of spread and should be used to cover the steps since the steps are 18′ wide.

The PROF 1K has the narrowest beam and is used to create a very bright and tight lighting area at the pulpit. This area could also be utilized for a soloist. The other two solo areas used the wider PRO 1K Ms because the area is designed not only for soloists but also for duets and trios.

To choose the appropriate degree of spread, you must know two pieces of data: one, how far the light throw is to the target, and two, how much width you wish to cover. A good rule of thumb for general stage wash is to cover 10’—15′ per ellipsoidal. Covering more that this may decrease foot candles to an undesirable level or leave huge hole when a lamp burns out in the middle of a service. Covering less than this will require more fixtures than necessary. From this point, consulting manufacturers and vendors about specific ellipsoidals will allow for the proper choosing of fixtures.

The two light bars over the stage (in theatre vernacular these are called ‘electrics’; thus, this light plot shows a 1st and 2nd electric) depict Fresnels for back lighting the various zones, and ellipsoidals for back lighting solo spots. The PRO 1K Ms are utilized again. Although they were used to cover 10′ -15′ in the general stage wash, they are used here for a much smaller area. The area of coverage is much less because of a much shorter throwing distance.

The light plot does not indicate, as a complete light plot would, the circuits / dimmers where each fixture is plugged in. Before indicating the dimmer assignments on this plot, one would need to consider the last question:

What can be added to the design to allow flexibility for special events?

Obviously more fixtures can give greater flexibility, but fixtures have to be plugged into ‘something’ (dimmers) and the ‘something’ has to have power. Minimally, the plot as shown would require 12 dimmers over the stage and 18 dimmers on the front bar with circuitry to allow you to plug two lights into one dimmer. If more lights were purchased, little space, electrically speaking, would exist for them to be used.

When budget is a concern, it is better to have more dimmers and circuits in place than routinely needed, versus spending on extra fixtures. Worse case scenario, have empty pipe space and raw power available to which you can add fixtures and dimmers as you grow.
This particular install design has 48 dimmers on the front bars and 12 dimmers over the stage. In addition, circuitry and power exists to for rental of 12 additional dimmers over the stage and 12 dimmers on the stage floor.

Obviously, one magazine article will not make any individual an expert on lighting design installation. I hope, however, that this article will provide sufficient knowledge so that any individual can converse with installers and/or consultants in an intelligent manner. The goal is to get what you as the buyer and user of the equipment needs- not what the sellers and installers think you need.