| Church Designs and Installations of Visual Communications Systems |
|
We live in a rapidly changing world – the world of technology. Communication has taken on an entirely different look. Visual Communication is here and it is becoming the norm for many of today’s churches. In many churches the hymnals and overhead projectors are giving way to integrated visual communication systems that incorporate computer, video and document cameras.
From announcements before service to song lyrics during worship to sermon notes during the message, these systems are accomplishing much by way of increasing the effectiveness of communication and enhancing the churchgoer’s experience. Other useful functions include communicating to parents that their children need attention in the nursery and viewing video (either live or prerecorded) in a format that the entire congregation can see clearly. Many churches are associated with schools who are now utilizing these upgraded worship facilities to conduct large gatherings of their students and families. Because churches represent a large number of meeting facilities in our cities, these buildings with their new capabilities, could become a common choice for groups needing to conduct multimedia meetings. This could mean extra revenue for churches whose facilities typically remain idle during the workweek. Creating a system that is properly suited to a church’s individual needs is a task that requires planning. My advice to anyone considering implementing a multimedia system in a church facility is, “Plan ahead!” The importance of planning and proper needs assessment cannot be overstated. This is especially true of new construction. Many churches wait until after the building is complete to consider designing a visual communication system only to find out that there church was designed in a way that makes it very difficult to implement this technology on the back end. There are many factors to consider when designing a building to accommodate a visual communication system. Among the many technical aspects of the design are such things as proper conduit for interfacing cables and supplied power for system components. In addition to the more technical issues are those issues that are related to the cosmetics of the system. If these issues are not approached properly they can render a very expensive system virtually ineffective. Let me explain. The goal in designing a visual communication system is to provide a means of communicating information and a view of the service to everyone in the building whether they are in the front row or the last seat on the back row. This should be accomplished without distracting from the service itself. It is therefore critical that the cosmetics of the system (that which people see) be the best that the individual components can provide. The most important issues in this regard are: the proper number of displays; the size of each display; proper placement of each display; the amount of ambient light between the viewers and the display; and the brightness of the displays. The number of displays and the size of each display are issues that can be very closely related. The number of displays depends on the building layout. Some buildings may only require one screen to provide an image that can be seen clearly from any seat in the auditorium. Others will require two or more screens of the same size but facing different directions to provide a view to the entire auditorium. Still in other situations it is necessary to consider the display size and the distance to the viewers. A typical rule for determining display height is to divide the distance from the last seat in the auditorium by six. At the same time the height of the screen should not exceed the distance to the first row of seats divided by two. Example Distance to last row of seats = 60 feet Distance to first row of seats = 20 feet 60 feet divided by 6 (for high resolution text) = 10 feet Screen width should equal 10 feet. Because the aspect ratio is 4:3 the screen height should equal 7.5 feet. 7.5 (screen height) times 2 = 15. This is less than half than double the screen height, which is the maximum (10 feet in this example). This is of course an ideal example, but this represents the goal for which to aim. In the event that it is impossible to get these figures to even remotely match then additional displays should be considered. It is worth pointing out that for most church applications these figures tend to be on the large side because typically a church is not displaying fine detailed information such as busy spreadsheets and technical diagrams. Most of the time the song lyrics and sermon notes are done in large fonts, which makes them legible on a smaller display. There is also a rule for how to determine the proper font size. The font should be 1.5 inches in height for every twenty feet between the viewers and the display. Example Distance to last row of seats = 60 feet 60 feet divided by 20 feet = 3 3 x 1.5 inches = 4.5 inches The font size on the display should be at least 4.5 inches in height in order to be seen clearly from the last row of seats. Properly positioning each display and the ambient lighting between the viewers and the display are also issues that are closely related. There may be a more technical way of determining the display location, but I have found that the easiest way is to first determine what would be the ideal location(s) for each display. (If the building is being designed for construction the architect should be able to determine proper positioning for the displays.) Sitting in different seats in the auditorium and checking the lines of site is a great way to begin. The display should be able to be viewed without having to move your eyes and/or head very far from the platform or altar. At the same time the displays should be high enough to be seen without having to dodge someone’s head in the line of view. Once again it should not be so high that you feel as though you are in the front row at your local movie theatre having to spend the entire service looking up. One of the factors that most strongly affect image quality is contrast. To put it simply, when dark is dark and bright is bright in the same image you have contrast. Contrast is typically affected by a few things but most often by two primary factors: The projector/display characteristics and the amount of ambient light between the viewers and the display. It is important when determining display positioning to consider facility lighting. This can be challenging because the idea is to keep the display close enough to the important activity so as not to be a distraction or an inconvenience while at the same time not placing it in the way of the lighting that is designed to highlight the important activity. Placing the display just outside the stage lighting perimeter is probably the best solution. This keeps the display close enough to the “action” so as not to draw people’s attention away while at the same time protects the display from the high-powered lighting that so badly affects contrast. Another way to increase contrast is to utilize rear-projection as opposed to front-projection. Rear-projection is utilizing a translucent screen that is designed similarly to a television screen. The projection device is placed on the side of the screen opposite the viewing audience, and the image is projected onto that side and viewed from the opposite side. If a building is not constructed properly rear-projection could be eliminated as an option. The reason for this is an entire room must be dedicated to the function of a projection room. A projection room must be deep enough to allow the projector to be placed far enough away from the screen to create the desired image size. Of course there are special lenses and mirrored systems that can make up for a lack of space but either of those significantly increase the cost of a system while at the same time reduce the amount of light hitting the screen. A projection room should be the equivalent to a dark room with all reflective surfaces covered in order to maximize the efficiency of the light output from the projector. A pastor that has a front projection system in his church once told me that if he had to go back and redesign his building and system that he would choose rear-projection because of the superior image quality. It is unfortunate that building design makes that a virtual impossibility. In a front projection scenario any ambient light in the auditorium will add to the light hitting the screen which competes with the light from the projector. The more ambient light the less contrast or the more “washed out” the image looks. In a rear-projection scenario the amount of ambient can be greatly reduced between the projector and the screen by “darkening” the projection room. This provides for much greater contrast and typically a brighter image. Proper planning is especially critical when considering rear-projection. Let’s talk now about some of the components that make a visual communication system. We will begin by looking at projectors. As mentioned previously we are seeing the overhead projectors giving way to the newer technology of LCD, DLP and ILA projectors. The progression to these newer technologies has been a very rapid one. LCD panels allowed the overhead projectors to be used for more than just still images created by light passing through a prepared transparency. They could now be used to display computer and video images in real time. From there the manufacturers began to combine the light source, lens and the LCD into one unit and called it an LCD projector. DLP (Digital Light Processing) was developed by Texas Instruments and has become very common in multimedia projectors. ILA is a combination of two technologies: the traditional CRT (cathode ray tube) and LCD to create what is called a light valve projector. The LCD projector seems to be the most common among those used in churches. These units are becoming smaller and brighter all of the time. The light output of a projector is measured in ANSI lumens. Lumens are the measure of light, and ANSI (American National Standards Institute) is the organization that governs the system of measurement. Just a few years ago a projector that had a rating of 300 ANSI lumens was considered very bright. Now it is not uncommon to see projectors with 2000+ lumens being used in churches. In fact there are some using projectors with 3000+ lumens. What is even more exciting is that these are not high maintenance machines that require a full time technician to maintain. In fact most require only the lamp and the ozone filter to be changed. The lamps can last from 750 to 8000 hours of use. Many are made to be mounted either in the upright or inverted position and can reverse their images for rear projection applications. These units typically have at least one computer input and one video (NTSC) input. Many offer multiple computer and video inputs. Most have zoom lenses that allow for flexibility in the placement of the units. Choosing the right projector is a matter of matching the needs of your application with the capabilities of the projector. In many cases the main issue is brightness. One may ask, “How bright is bright enough?” That is a difficult question to answer, especially if there is more than one person trying to answer it. The best place to begin is to establish some point of reference. This can be accomplished by looking at foot- lamberts. When a projector’s brightness is measured in ANSI lumens, a fixed image size is assumed. A projector that has a rating of 500 ANSI lumens will look great in a conference room where the image is approximately 60 inches diagonal. That same unit will look quite dim when trying to produce an image that is three times that size in a very well lit church. Measuring the foot-lamberts of a particular display can help clarify things a great deal. Foot-lamberts are determined by taking the lumens and dividing them by screen area. Example ANSI lumens = 1500 Screen size = 9’ x 12’ 9’x12’=108 square feet 1500 divided by 108 = 13.89 foot-lamberts A typical foot-lamberts rating for a television is 30; for a home theatre it is 8; and for a movie theatre it is 14. This brings us to our next component: the screen. The reason is that screen gain also affects foot-lamberts. When a screen is said to have a gain of one, it is neither adding to nor taking away from image brightness. As gain increases so does the foot-laberts rating. Example Foot-lamberts = 13.89 Gain = 1.8 13.89 x 1.8 = 25 foot-lamberts Can you see how important screen gain can be? There is a catch though. This will require a bit more discussion about screens. There are many different types of screens: front projection, rear projection, motorized, fixed mounted, portable, optical, diffusion, etc. Some churches choose front projection because it is not as costly as rear-projection. Some choose to mount a motorized screen above the baptismal directly to the back of the main platform. The screen can be lowered when needed and raised when after use. Others choose to have a permanently mounted screen or screens while others choose to use portable screens. Choosing the right type of screen is a process of matching the characteristics of the screen to the needs of your application while keeping in mind the budget limitations. Front projection screens are made with different surface types for specific applications. The variations in the designs usually balance two opposing concerns: screen gain and viewing angle. This is where the “catch” comes in. You see, as screen gain increases the viewing angle typically decreases. The screen acts as a reflection device for whatever light hits it. A screen can be designed in such a way that it concentrates that light in one direction resulting in increased screen gain. If the need is to provide a greater dispersion of the light resulting in wider viewing angle then gain typically suffers. An easy way to understand this is to think of light as paint. The larger area needing painting the thinner the coat of paint will become. In the same way the larger the area of light dispersion, the less intense it will be. This concept holds true for front projection screens as well as rear projection screens. Rear projection screens can be manufactured from a glass, a form of Plexiglas or a flexible material. These materials are prepared as translucent surfaces that disperse the light from the projector to create the image. The two most common types of rear projections screens used in fixed installations are optical and diffusion screens. Optical screens are the equivalent to a large group of tiny lenses put together to create the screen surface. This type of screen has very high gain while at the same time maintaining a very wide horizontal-viewing angle. The down side is that optical screens are quite costly and offer very little vertical-viewing angle. These screens are not uncommon among consumer-grade projection televisions and actually work quite well in that environment. The reason is that a television does not normally need much of a vertical-viewing angle because it is typically at eye level with the viewers. This is not generally the case with church display systems and this makes the diffusion screen a better fit for many of these applications. The reason is, with diffusion screens, the viewing angle remains constant in the horizontal and vertical viewing plains. One church that we worked with had 80” televisions suspended from the ceiling as their displays. The images (although much too small for the building size) looked fine if you happened to be seated toward the back of the building and had a direct line of view. Those seated in the front rows were virtually unable to see the image. Because the televisions had optical screens all of the light was dispersed horizontally and virtually none vertically. One of the main concerns for the church as we designed a new visual communication system was the viewing angle. We installed two 150” diffusion coated screens that offered a gain of 1.3 and a viewing angle of approximately 75 degrees off center axis. One can literally stand directly under this screen, next to the wall in which it is mounted and still see the displayed image. The people who make it their habit to sit in the front row are thrilled with the improvement. One issue to be aware of when considering rear projection screens is screen non-uniformity (also referred to as mottling). For screens that exceed approximately six feet in either width or height mottling is quite common. Mottling shows up as wavy lines in the screen material that are more apparent with dimmer light. The testing process involves placing an incandescent light on one side of the screen while viewing for the opposite side. There are tolerance levels established by each manufacturer for what amount of mottling is acceptable. Because the manufacturing processes are kept confidential by each manufacturer, it is difficult to determine why mottling occurs. One way to minimize the effects of mottling in overall image quality is to increase the light from the projector. In one church, mottling was most apparent as the camera was panning across a white wall. The mottling appeared as irregular-vertical streaks that remained stationary as the actual image content moved across the screen. In this case our recommendation was to darken the walls that were appeared behind the pastor when the camera was focussed on him. Let me encourage you by saying that mottling is not terribly apparent to the casual observer or often to the more technical observer and should not keep you from choosing this type of screen. It is an issue to be aware of and should be a topic of conversation with the screen manufacturer you choose. We’ve talked about the two most common and fundamental components of a visual communication system: the projectors and screens. Let’s talk briefly about the source components for these systems. The most common are computer and video (either live or recorded.) In the before mentioned church the main application for the system was to provide a great view of the service from any seat in the house. The system will also be used for song lyrics and to view prerecorded video material played back from Beta tape. This church also utilizes a satellite system to pipe in other broadcasts as desired. Other churches use visual presenters (also referred to as document cameras) in place of overhead projectors. A visual presenter contains a camera that captures an image of a document or an object and sends that image to an external display device. This allows a presenter to share printed material or hand written notes with the congregation. When integrating these components into a system it is sometimes necessary to amplify the source signal if the source and the display are placed far apart from one another. Typically a computer signal does not carry nearly as far as a video signal and therefore is more often the source in need of amplification. Either line amplifiers or distribution amplifiers handle the amplification. The choice of amplifier depends once again on the application. One common choice is to install a distribution amplifier that receives a VGA signal from a computer CPU and sends the signal to the local monitor and an amplified signal to the large-screen display. Many projectors can receive these multiple sources and be selected by using the source selection on the projectors. A simple way to handle this is to hard wire the projector’s remote control and place it near the sources. Third party remote panels can be used as a cleaner surface-mounted solution. A common choice is to route the sources through a separate switcher at the location of the sources and feeding a single signal out to the display. In some cases the video signal is fed through a device called a line-doubler or scan-converter that converts the computer signal into a television video signal. That signal is then fed through a video switcher complete with fade controls. This allows for fades from computer text (e.g. scripture references) to the view of the person ministering. These systems can serve congregations quite well but it always important to remember that the function is to serve. A system should never be design to “steal the show” but to augment the communication process. Careful planning, proper needs assessment and wise product selection will yield the best system for your church. Our hope is that this information will give you a good idea of what to look for when considering this type of technology for your church. Don’t be afraid to ask for advice. Expert advice can help you avoid many unnecessary headaches and help make your experience in this sometimes-complex industry a pleasant one. Enjoy the journey! |
