Have You Seen the Light?
A practical usage guide to video projectors
Rather than repeat the many existing technical dissertations on the inner workings and science behind projector technology, let's take a brief look at some basic technical differences between them and then deal with some real-world situations that projector users will encounter in the worship environment.
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Digital light processing (DLP) and liquid crystal display (LCD) are the two most common types of projector technology. Shown here, a portable Epson three LCD projector with a small footprint and price tag. Photo by Bennett Liles. |
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First Baptist Church of Jonesboro, Georgia uses the massive Christie Roadster S+12K to paint a picture behind the choir. The image is projected from a control room that rests behind an expansive auditorium. Photo courtesy of First Baptist Church of Jonesboro, Georgia. |
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From a control room with a video switcher, techs can run a high-definition video signal into a projector with a DVI or HDMI connector. Photo by Bennett Liles.
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Video projectors with short-throw lenses, located just inches behind the screen, can be used for rear-screen projection. Custom stands can hold the projectors, which can spread an image six feet wide or more. Photo courtesy of Multi Media Services. |
The two most common types of projector technology are DLP (digital light processing) and LCD (liquid crystal display). LCD is the older of the two and is well established. These machines carry lower price tags than DLP models and most of the smaller, portable projectors use LCD technology. DLP projectors use an array of rapidly moving microscopic mirrors and usually a color wheel to generate their light spectrum output. If this sounds expensive compared to LCD, it is, but what is gained with the higher price tag is brighter images (more lumens), higher contrast ratio, and better performance in high ambient light environments. 3DLP projectors use a prism to split the light spectrum between three separate DLP chips and thus generate far better color and contrast ratio, but the price for this is very high. 3DLP technology is usually found only in the large-venue, high-output models costing well over $10,000.
As the brightness capability in lumens goes up, so does the price, but the trend for some time now has been toward more lumens for less. You will pay less than a dollar per lumen for the machines on the smaller end and about a dollar per lumen in the midrange market. Depending on the ambient light situation, a projector capable of 4,500 lumens will handle the needs of all but the largest sanctuaries.
At the very top of the line are behemoths like the Christie Roadster S+12K 12,500-lumen projector in the First Baptist Church of Jonesboro, Georgia. Nearly the size of a washing machine, the unit paints a dazzling picture behind the choir and throws this image all the way from the control room behind the massive auditorium.
Of course, all those lumens are generated by the lamp and this component represents the largest ongoing expense of operation. Mid-market projectors will require lamps costing $450 or more and the specs on these usually call for a lamp life of about 2,000 hours. As a practical matter, it is wise to subtract about 25% from this figure and use that as the time for lamp changes. The lamp will begin to dim noticeably before getting to the maximum advertised hour mark. The best way to extend lamp life, other than making sure to turn it off when not in use, is to clean the air filters frequently. In a thickly carpeted sanctuary or dusty environment, the filters will clog at least three times faster than in a clean, hard-floor room. Set a schedule for filter cleaning, and stick to it. Most new lamps include a new filter, but if one is not included, when the lamp is changed the filter should be cleaned. Note how dusty it gets, and if it is pretty well clogged, set a higher cleaning frequency on the schedule. It pays.
WIRED OR WIRELESS?
One of the latest built-in features for video projectors is wireless connectivity. Although wireless projector connection has been around for a while with the IEEE 802.b wireless standard, newer models with built-in wireless have begun using IEEE 802.11g for higher data speeds. The computer to be used must have the proper software installed and include the applicable wireless communication card. If 30-frame video is used for IMAG, wireless is not a viable option.
The best way to go with connection for video sources, particularly from a control room with a video switcher, is to run a high-definition video signal into a projector with a DVI or HDMI connector. Most projectors, however, will allow the connection of standard 525-line composite video through RCA connectors.
These video input connectors are usually color coded yellow. The high-def signals using DVI or HDMI connectors have a cable run limited to around 15 feet, but this distance can be greatly increased by using DVI/HDMI extenders. These come in pairs with one piece as the transmitter and the other as the receiver. They may be connected by CAT-5 computer network cable for runs up to 320 feet or by fiber optic cable for even longer runs. The standard composite video lines can normally be run a hundred feet or more with no problem. A four-pin S-video connection will offer slightly better analog quality, and many video projectors include the Svideo connector. Among the analog video signal formats, component is high quality but it requires three separate coaxial cables for the signal. Many mid-market video projectors include a set of component video RCA connectors color coded red, green, and blue.
CONTROL OPTIONS
Of course, the easiest control method is simply using the local panel on the projector. But when direct physical access is not practical, a hand-held infrared remote with line-of-sight transmission carries no additional expense. However, infrared is line-of-sight and the range is limited. This may be extended considerably by using a control processor with a touch panel from AMX of Richardson, Texas, Crestron Electronics of Rockleigh, New Jersey, Extron Electronics of Anaheim, California, or others. The touch panel may have a hard wired or radio connection with the processor, and from there a tiny cable carries the control commands to a small "IR bud" that sticks onto the infrared receiver window of the projector.
Mid-market and higher products include nine-pin RS-232 connectors for direct serial control. This also allows for feedback from the projector for such parameters as lamp time, power status, temperature warnings, security alerts, air flow problems (dirty filters), and lamp failure notices. The RS-232 serial protocol has been around for decades and is simple, versatile, and well understood in the industry. A processor unit will translate between the RS-232 connection and a touch panel or computer.
Many of the same projectors offer an RJ-45 connection on the unit for direct networking using the manufacturer's proprietary protocol. The RJ-45 port is the same type used by computer network cards, switches, and hubs. The projector essentially becomes a computer on its own network. The software provided with the projector allows the user, sitting at a remotely located computer, to monitor the status of many parameters and to control several aspects of the projector's operation. Automatic sequences of commands may also be used including automatic shut-off at a pre-determined time. However, it is advisable to use this feature only with serial control. With this method, "On" and "Off" commands are separate whereas with infrared control, there is usually only a "Power" command which will turn the unit on when it is off and turn it off when it is on. If the projector has been left running, an infrared power command will turn it off at the assigned time, but if the unit is already off when the power command is automatically issued, it will turn on.
Most video projectors have a "sleep" feature that senses when there has been no mouse or keyboard activity during a computer display and will go into a very dim condition to save the lamp. The wait time before this occurs can usually be set on the screen menu along with other functions such as image reversal for rearscreen projection. The sleep mode can be outsmarted if a video source such as a DVD/VHS player, camera, or video switcher feed is left connected to the input. Even with no program video, some projectors will interpret the sync pulses on the video line as activity and remain on at full brightness until manually turned off--or until the lamp burns out.
GO LONG -- OR SHORT
For projectors with powerful lamps and high-lumen output, special long throw lenses will enable the unit to be placed far behind the viewers, perhaps in a balcony, and project an image that will fit a distant screen. The full intensity of the light is concentrated rather than being allowed to increase in area as the projector-screen distance increases. Conversely, short-throw lenses are often used for rear-screen projection where limited depth is available in the projector room. Video projectors may be located mere inches behind the screen, usually on special stands, and spread an image six feet wide or more.
CONNECTED BUT NOT PROJECTED
For computers to be used with the projector for video or graphics, a standard point of procedure is to check the operation with all of the hardware connected. Computers require specific video drivers to be installed in order to properly use the secondary monitor output that feeds the projector. All too often, someone brings a computer to a service or other event, setting it up at the last minute only to find that when it is connected and the projector is turned on, squiggly lines, error messages such as, "sync is out of range," or no image at all is shown. If a new computer is to be purchased or borrowed for use with the sanctuary video projector, take it to an expert to have the display cloning set up for projector use and know the projector's recommended optimum source resolution. This will probably be at least 1024 x 768 pixels (XGA). Above all, try it out with the actual projector and cable while there is time to fix anything that doesn't work. If a backup computer has to be used, the presentation content for the service should be duplicated on a USB flash drive for quick transfer to the other computer.
Video projectors have become standard equipment for many churches and, in light of this growing trend, a solid understanding of their operational capabilities and pitfalls will allow your congregation to keep right on seeing the light.
Quick Links
CHRISTIE DIGITAL SYSTEMS INC.
Christie Roadster S+12K
(866) 880-4462 or (714) 236-8610
www.christiedigital.com
