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Topic: Just when you think you've seen it all...

John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 07-24-2002 03:32 PM

A "rule of thumb" is that for a matte white (gain = 1) screen, you need about 5 watts of power for each square foot of screen area.

Many assumptions in this "rule of thumb" (e.g., 2-blade shutter of about 50% efficiency, modern coated lens design, proper optical alignment, etc.).

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
e-mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

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Peter Dougherty
Film Handler

Posts: 36
From: Maspeth, NY, USA
Registered: Nov 2000

posted 07-24-2002 03:47 PM

quote:
I've run xenon projectors from time to time, but never 4.5k ones. What screen size would you use this for?

Usually with screens over 40' or more (typically the larger houses in multiplexes). We used 4K Ushio lamps on a 33' screen at one single I worked at 10 years ago, but the lamphouse and optics were so abominable (Xebex Super-Sol) that we STILL couldn't get more than 12.5fL on a C/S picture, and then only in the centre. Closer to 3 around the left edge and 5 on the right!

I hope that thing is rotting in a landfill somewhere today!

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Dick Vaughan
Phenomenal Film Handler

Posts: 1032
From: Bradford, West Yorkshire, UK
Registered: Jul 2000

posted 07-25-2002 02:36 AM

Stephen

You are right the original 2D Imax installation here in Bradford did use 4kW Osram on a screen 48' x 64'. We later used ORC 4500 W until we closed for rebuilding in 1997.

Since we eopened we use Osram 7kW lamps in each of the IMAX SR projectors.

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Mathew Molloy
Master Film Handler

Posts: 357
From: The Santa Cruz Mountains
Registered: Nov 2000

posted 07-25-2002 03:47 AM

Hey, the Egyptian in Seattle had two of these bad boys stolen from the booth during our renovation a couple years ago...I was looking on ebay for some time afterwards but never saw them come up...I'm wondering if these are the same?

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