Basic Lighting Instruments: Pros and Cons- Part I

In Uncategorizedby tfwm

In the past decade a paradigm shift is taking place in our commonly held views of rooms in which we worship. The term sanctuary is being replaced by “Worship Center” or “Celebration Hall”.

The Sanctuary, a room often built with as much majesty as the budget would allow, brings with it the idea of a place where one is to be reverent and respectful. This room is designed for its aesthetics, not for its functionality.

However, realizing that worship takes place in many forms, the ancestors to sanctuaries; i.e. Worship Centers etc, are being designed with more functionality in mind. Platforms have given way to sizable stages; in some instances with stage wings. Rooms where the preacher preached and song leader did little more than call out the next hymn number are now being modified to accommodate bands, orchestras, drama, and; do we dare say it? – dance! Well-designed audio and lighting systems are now the norm in new churches.

Difficulty comes in expecting lay members of a building committee to make intelligent decisions on the design of a lighting or audio system if they have had little or no training in these areas.

Installation companies usually have packages to sell you, but do these packages meet your specific needs? And who decided what your needs are- you or the Installation Company?

I wish to take some time to educate you on the facets of basic lighting instruments, their pros, cons and typical uses.

Four most commonly used theatrical instruments:

Ellipsoidal, Fresnel, Par Can and Cyc.

Note: the author realizes that there are many types of moving lights available on the market and that these lights are being utilized more and more. However, it is not in the scope of this article to tackle the use of these lights.

Par Can
Par stands for Parabolic Aluminum Reflector. That is, the reflector is in the shape of a parabola.

Sometimes the light is referred to with a number following its name, PAR 64, PAR 56. The number indicates the number of 1/8th inches in the lens’ diameter. That is, a PAR 64 has 64 1/8th inches in the diameter of the light. Thus, the light is 8 inches in diameter.

A PAR’s lamp and lens is all one unit. So, when you desire to change the lens for a different light spread, you will change a entire lens-lamp assembly, much like an automobile’s head light. Lenses are designated as Wide Flood, Medium Flood, Narrow, and Very Narrow. A wide flood lens has the most dimples while the very narrow one will have none or may be slightly rough in texture.

The light output of a PAR can has the following characteristics:

1. Oval in shape, (the oval can be rotated to a desired orientation)

2. Moderately controlled light beam; even though the majority of the light is in a somewhat defined area, extraneous light emanates from the instrument in a very broad pattern.

3. Color tends to be towards the red end of the spectrum, especially when dimmed.


More economical
Lighter weight than other instruments.


Minimal light control
Color temperature changes when dimmed.
Entire lamp-lens assembly needs to be replaced when lamp burns out.

Uses: Front lighting, back lighting, Accents to Set pieces, Accent to curtains or draped material.

Available: usually in 500W and 1000W fixtures. Low voltage PAR 32s (pin spots) also available.

ETC’s Source Four PAR? has a lamp that is separate from the lens. This provides for more economical lamp replacement and you have the option to change the lens without changing an entire lamp-lens assembly. In addition, if you use ETC’s Source Four Ellipsoidal, one lamp, which maintains good color even when dimmed, it fits both instruments. This is not the case for conventional ellipsoidals and PAR cans.

This instrument, which has been called the Workhorse of the theater, arrives at its name once again, because of the shape of its reflector. The reflector is essentially an ellipse. Recall that an ellipse has two foci (F1 and F2).

The lamp sets at F1 and the reflector focuses the light to F2. Consequently, in order for this instrument to be functioning optimally, the lamp must first be sitting at F1. This is called setting the Bench Focus of the instrument. It is achieved by adjusting focus knobs / screws on the rear of the instrument. These adjustments result in moving the lamp further in or out of the reflector, thus putting the lamp at F1. F1 is achieved when the projected light field is even from center to outside edge.

As you may or may not know, an ellipsoidal is the type of instrument that has a place to insert patterns for projecting on scenery, actors, or cycloramas, etc. These patterns, more properly known as gobos or templates, are actually inserted at F2. This is also called the Gate.

Also existing at F2, or the gate, are the shutters which allow you to trim the projected light pattern to almost any four sided shape desired, thus giving a great deal of control over where the light does and does not go.

Finally, the lens of an ellipsoidal gives the instrument its particular light spread. For example, an ellipsoidal which will produce a 6″ diameter circle at distance “X” may be desired for a soloist application but an ellipsoidal which will produce a 12″ diameter circle at distance “X” would be desired for a general stage wash application.

The difference between these two instruments is going to primarily be in the lens. The way in which ellipsoidals use various lenses is designated as follows: 6 X 9, 6 x 12, 6 x16 etc. The “6” indicates that the instrument has a 6″ lens. The other numbers, the 9, 12, 16, indicate the distance from the lens to the gate. Therefore, a 6 x 12 is an instrument which has a 6″ lens, and is 12 inches away from the gate. Knowing that the further the lens is from the gate, the more narrow the beam of light, a 6 x 16 is more narrow than a 6 x 12, which is more narrow than a 6 x 9.

NOTE: A 6 x 9 Altman 360Q ellipsoidal will not have the same exact spread of an ETC Source Four 6 x 9 ellipsoidal.

The second way to distinguish lens spreads of ellipsoidals is by degrees. A 30-degree instrument will have light leaving the lens creating a 30-degree angle with its beam. Hence, a 50-degree instrument has a much broader spread than a 26-degree instrument. The following table should give you some help in putting this all together.

ETC Source Four
6 x 9: 36 deg
6 x 12: 26 deg
6 x 16: 19 deg


Light output is even across its field
Light output shape is very controllable
Can use gobos
Light color is maintained while dimming


More expensive
Generally heavier

Uses: General stage wash, creates tight solo areas, utilizes gobos for adding texture or to create desired ambiance, back lighting for solo areas.

Available: 500W, 750W, and 1000W fixtures. Be aware that new lamp technology provides 575 W / 600 W bulbs that will give output somewhat equal to that of conventional 1000W lamps. Inquire before you rent or buy.

Okay, first of all, the correct pronunciation is fer-nel. It is named after the Frenchman that discovered that the thickness of a lens is not what causes the light to bend a specific degree, but rather, the angle at which the lens’ surface meets the light determines the amount of refraction.

Note: if one were to take the Plano Convex lens and remove all of the shaded areas, the leftovers would be little pieces of curved lens. Set the curves on the base of the lens and you would have a Fresnel lens.

So what’s the point? A much lighter instrument is created when a significant portion of the glass is removed.

The mechanism of a Fresnel allows its light output angle to be adjusted by actually moving the lamp within the fixture closer or further away from the lens. The closer the lamp is to the lens, the wider the light angle; the further the lamp is from the lens, the more narrow the light angle.

Although the light output of a Fresnel is not as controllable as an Ellipsoidal, it is however, more controllable than a PAR Can. In addition, for increased control, barn doors can be added to the front of the instrument allowing for some shaping of the light output. The projected light is circular in shape and has a very soft edge. This soft edge simplifies the combining of several Fresnels into one wash.


Light Output angle easily adjustable
Soft edged light easy to blend with other lights
More expensive models have a very even field of light distribution


Soft edged light cannot be controlled tightly
Less expensive models can have dark spots in their field of light distribution.

Uses: Back lighting color washes (I would strongly recommend these over the use of strip lights), scenery washes; especially where the desired is to have the light fade to the edge and not be cut off, side lighting washes for dancers or other movement.

Available: Lens diameter sizes: 6″, 8″, 10″, etc. up to very large TV / film Fresnels. Lamp sizes: 500w, 750W, 1000W, etc. up to metal halide lamps able to mimic sunlight.

This instrument was designed with basically one use in mind; to light very large surface areas from a very short distance. Most Cyclorama lights can light a 14′ – 16′ wide area at a distance of about 3′. There is no control over the shape or focus of this instrument’s light output. Once again, it is designed to spread evenly and at a very wide angle.

Available: 1000W, 1500W. Also in single, double, and triple circuit units

In Closing
The information presented above is sterile data at best if not applied to the needs of an organization/church/theatrical company. Subsequent articles will marry the knowledge of theatrical instruments with lighting needs, thus generating a useful lighting system design.