Da-Lite > Educational Materials > Selecting Front Projection Screens for Today's Presentation Applications Selecting the Right Front Projection Screen Surface Da-Lite Screen has identified six basic criteria for selecting the right screen surface. Each criteria is designed to provide characteristics a screen must posses to meet the applications objectives as discussed earlier in this manual. These Presentation Media criteria are as follows: CRITERIA #1 - PROJECTION METHOD Determine the primary type of projection method to be employed. If multiple projection methods are to be used equally, determine which one has the most demanding requirement and use that as your selection criteria. For example, in the case of an application requiring a front projection screen to display both LCD Video and slide projection, use LCD Video as the selection requirement due to its need for a screen surface with high gain qualities. Video Light Valve Technology - A video projection system generally using a high power xenon arc lamp to project a bright (up to 7000 lumens) video image by using an electron beam to scan and construct the image. The image is projected through a single interchangeable lens for precise color registration and easy set-up. CRT Technology - A common video projection system using three-tube projectors (one for red, green and blue) with a fixed focal length and light output of approximately 600 to 1600 lumens. Alignment of the three tubes is critical for best resolution and color rendition. LCD Technology - This low-cost technology uses a conventional light source, usually a halide arc lamp, to project an image by passing light through three internal liquid crystal displays -- one each for red, green and blue. Each image is then combined by a series of mirrors into a single image. Resolution is lower than CRT-based projectors and produces a lower light level at around 600 lumens. DLP Technology - This technology is based on the Digital Micromirror Device™ (DMD™) which uses over 500,000 microscopic mirrors on the SVGA chip to reflect images on screen. 35MM Slide transparency - One of the most poplar methods of displaying single-frame photography. Like other portable film projection methods the slide's continuous tone properties and the projector's high light output (varying from 1000 to 6000 lumens), provides an excellent image -- showing fine detail and exceptional color rendition. Overhead\Opaque Projection Overhead transparency - In business and educational settings, the overhead projector has become an indispensable projection choice. Its flexibility, ease of use and high output light source of approximately 3000 lumens provides a projection method individual presenters can use in their own personal manner. Overhead LCD panel - Same method of projection as the overhead transparency but light is projected through an LCD panel connected to a personal computer. The number of screen pixels and screen mode (i.e. VGA in the panel) determine the resolution quality of the image and color rendition. Generally, ambient light should be kept to a minimum for best image quality. Light output is greatly reduced because light is projected through a number of layers. Opaque - Designed to project original documents and small three-dimensional objects through reflectance. It has a relatively low light output of approximately 150 lumens, making it necessary for a higher gain screen or to moving it closer to the screen. 3D Projection Three-dimensional and specialty projection - The polarization of images to produce three dimensional images substantially reduces light output dictating a much higher gain screen than any another form of projection. Also, some front projection screen surfaces actually disrupt the polarization effect. Some special video projection situations require a higher contrast due to high ambient light conditions. In these cases, a curved screen is generally recommended. CRITERIA #2 - AMBIENT LIGHT CONDITIONS Part A - Determine whether or not light conditions are controllable to minimize ambient light when needed -Controlled light assures no substantial stray light is allowed to enter the room that would increase ambient light levels to a point where the projected image is affected. Part B - Determine if uncontrolled light is directed at the screen causing the projected image to "washout". An example is uncontrolled light from sources such as concealed ceiling lights directed on to the surface of the screen. <--previous page introduction glossary next page -->   For pricing information, please contact Media Fabricators, Inc. via e-mail at [email protected] or via telephone at 323 937 3344.