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Posted by Bill Enos (Member # 440) on 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?
Posted by Aaron Sisemore (Member # 145) on 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
Posted by John Pytlak (Member # 331) on 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
Posted by Gordon McLeod (Member # 33) on 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