All too often, the selection of a video projection screen is treated as an afterthought. However, the performance of an expensive new projector is intimately tied to the screen it projects on. The screen and the projector work interactively, and understanding the relationship between them can be complicated and highly technical. Basic FactorsScreen size is perhaps the most basic parameter. To determine screen size, use the rule of thumb from the Society of Motion Picture Engineers: divide the screen-to-front-row distance by two—this should be the approximate width of the screen. For another width measurement, divide the screen-to-last-row distance by six—it should be about the same width as using the front row distance calculation, but use the larger size. Yet another method for determining screen width is to base it on audience size (see chart below), also from the Society of Motion Picture Engineers.
Table formulated by the Society of Motion Picture and Television Engineers. Gain is a measure of screen "brightness." Since a screen does not generate light, gain refers to the screen's ability to reflect light from the projector. In the case of rear projection, gain refers to the screen's ability to transmit light. A higher gain means a brighter image, but the tradeoff is in a reduced viewing angle. Viewing angle is a measurement in degrees of how far to the right or left of the screen centerline you can sit and still see the image. Typically, viewing should not be more than 45 degrees away from the centerline. Gain and viewing angle are related. High-gain screens achieve their gain by directing more of the projector's light into a narrower viewing angle. Low-gain screens are designed to spread the image over a greater viewing angle. Depending on an application, high gain is not necessarily better than low gain. Screen UsesScreens and their frames and mounts are designed with specific uses in mind. The main categories of use are portable, classroom, and sanctuary. Portable screens are usually five to seven feet measured diagonally, weigh from 10 to 18 pounds, fold compactly, and set up easily. Some portable screens have a pneumatic scissors mechanism for raising and lowering the screen surface from the base. Others consist of a frame and removable/interchangeable screens. Classroom screens are usually wall-mounted or portable. Wall- and ceiling-mounted roll-up screens for classrooms are available with either a manual or an electric lowering and retract mechanism. Sanctuary screens are usually permanently mounted. The screens themselves can be either fixed or retractable. Most retractable screens for sanctuaries are mounted on a wall or the ceiling, but some rise up from a floor or cabinet mount. When used in the sanctuary to support the sermon or other presentation, the screen should be close enough to the presenter so that viewers can see both the screen and the presenter without turning their heads. This usually means placing the screen over the platform. Dual screens, one on each side of the platform, may be necessary in large churches. Viewer sightlines should not be obstructed by balconies or low-hanging chandeliers. Make sure light, either natural or artificial, doesn't fall on the screen—shades and draperies can help. Reduce light levels when the projector is operating. Darkened rooms provide better contrast and resolution and reduce the brightness requirement of the projector—a money-saving option. Screen SurfacesHigh-gain screen surfaces are useful in a fully lighted room. These screens are usually covered with beads of glass or highly reflective plastic. High-gain screens have a limited viewing angle, since they direct reflected light to a narrow, more concentrated area for increased brightness in that viewing area. A matte white screen is preferred for applications that require a large viewing angle. If the room cannot be darkened sufficiently for the wide scattering of a matte white screen, you might need to choose a more powerful projector. A rear projection application is often preferred to front projection. Screens used for rear projection are translucent and appear gray as opposed to the white surfaces of front projection screens. Rear projection screens typically have wide viewing angles and, with an appropriately bright projector, are visible even in full sanctuary lighting. Plasma Displays and Liquid Crystal Displays (LCDs)Plasma displays and liquid-crystal displays (LCDS) are not screens but they can replace them in many applications. These devices present information directly from computers, VCR and DVD players, and live video cameras. No projector is required. Plasma display devices have great image clarity and contrast, are usable in a fully lighted room, and are available up to 102 inches wide. LCDs are cheaper and not as bright, but have a longer life. The maximum width of an LCD display is about 50 inches, but future LCD displays will be larger. —Quentin Wagenfield; Copyright © 2005 Christianity Today International. Originally appeared in Your Church. Discuss1. What feedback have we received from the congregation about our screens? 2. How closely does the size of our screen match the size of our congregation? 3. What changes can we make to the sanctuary to enable people to better view words and images projected onto a screen?    Holy WeekIn "Holy Week," you'll find articles to help you appreciate Palm Sunday, Maundy Thursday, and Good Friday, and discover great worship ideas for each.  Returning to RitualHow to enrich worship by drawing from the church's rich historical tradition. Getting Good Press How the media can help you reach out. Multimedia and Worship Avoid common media mistakes during praise and worship time.
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