Front Versus Rear Projection
I recently subscribed to Widescreen Review and at the same time purchased back issues through January 2006. I have enjoyed the technical details, but would like information on the design considerations and trade-offs in using projectors as front projectors versus projectors behind the screen.
Jay Davis-Kenneth J. Davis
Editor-In-Chief and Publisher Gary Reber Comments:
Welcome to Widescreen Review. I’ll make this brief, but extensive coverage can be found in various articles over the years and in our Imaging Science special edition. Our Web site search engine can help you to find back articles related to this topic, especially the series on building the magazine’s reference home theatre.
Essentially, the benefit of mounting a projector in a rear-projection environment is better contrast ratio and significant reduction in projector noise that can be heard in the main theatre room. With projectors capable of deep black levels, rear projection can optimize such performance because the screen material rejects ambient light and light reflections from affecting contrast performance. This is because a rear-projection screen will let light out into the theatre room from behind but reject light penetrating the rear-projection room. As for noise reduction, a projector located in a rear-projection room will have significantly less noise output into the main theatre room, especially with soundproofing of the rear-projection room. This eliminates an otherwise annoying obtrusion in the main theatre room. Of course, there are ways to soundproof a projector located in the main theatre room using soundproof enclosures. One of the drawbacks of rear-projection is the necessity of a dedicated room behind the screen. The depth of this room can be essentially halved with the use of a first surface mirror assembly, which works quite well when properly installed. But for optimum performance, a straight-on light path with no reflection is preferred.
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