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Author Topic: Throw Bill Enos Film God Posts: 2081 From: Richmond, Virginia, USA Registered: Apr 2000 posted 11-06-2001 12:27 AM                     Is there a distance, or screen size or some combination of factors that would make the length of the throw a consideration in determining lamp power in an indoor theatre? Or is there just not enough crap in the air to make a difference?  |  IP: Logged Aaron Sisemore Flaming Ribs beat Reeses Peanut Butter Cups any day! Posts: 3061 From: Rockwall TX USA Registered: Sep 1999 posted 11-06-2001 12:38 AM                     The bigger the screen, the shorter the throw, the larger the lamp wattage to get the same brightness. -Aaron  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 11-06-2001 07:24 AM                        The distance from the projector to the screen ("throw") has almost nothing to do with the amount of power required to light a given sized screen. The most important factors are the AREA of the screen, the GAIN of the screen surface, the SHUTTER EFFICIENCY, and the EFFICIENCY of the optical system (f/number of lens and lamphouse, transmittance of the port glass, alignment of the lamphouse, cleanliness of the optics, etc.). Particles or smoke in the air have a negligible effect on screen luminance, but can scatter light and reduce contrast. ------------------ John P. Pytlak, Senior Technical Specialist Worldwide Technical Services, Entertainment Imaging Research Labs, Building 69, Room 7525A Rochester, New York, 14650-1922 USA Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243 E-Mail: john.pytlak@kodak.com Web site: http://www.kodak.com/go/motion  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 11-06-2001 09:03 AM                     Port glass is a big light eater. Also mismatched optics. Some older xenon lamphouses are less efficient with modern lens because of the collector design  |  IP: Logged

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