|
|
This topic comprises 2 pages: 1 2
|
|
Author
|
Topic: anyone using the new Harkness Hall P1M (microperfored 0.5mm) screen ?
|
|
|
|
|
John Pytlak
Film God
Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000
|
posted 11-30-2000 07:34 AM
The problem with curving a matte (gain=1) surface is cross-reflections. Since a matte surface reflects light in all directions, curving it reflects some light across the curve of the screen, reducing contrast. A high gain screen is very directional, acting somewhat like a mirror in its reflection pattern. So it needs to be curved to reflect light toward the center of the audience, or the illumination uniformity will be poor. But because gain screens are so directional, contrast-reducing cross-reflections are much less of a problem. The screen manufacturers use proprietary coatings to make "gain" screens like the Spectral or Perlux. Using a combination of metallic and white paints on a drive-in screen may simulate these coatings, but I suspect it would have been hard to control the gain precisely or uniformly.
------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
| IP: Logged
|
|
|
|
John Pytlak
Film God
Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000
|
posted 11-30-2000 11:36 AM
David Baum originally asked about the Harkness Hall MP screens. (microperforated 0.5mm screen)
AFAIK, the MP screens with 0.5mm perfs were originally developed especially for Digital Cinema applications, where the projected pixels created a very objectionable moire (interference) pattern with the 1.2mm perforations of regular screens. According to Harkness Hall's product data, the regular screens have 1.2mm perforations, occupying about 5.3% of the screen area. Sound attenuation is about 2dB per octave above 2KHz. The MP screens have 0.5mm perforations,occupying about 1.8% of the screen area. Sound attenuation is about 4dB per octave above 2KHz. The smaller perfs of the MP screens should be less prone to form objectionable moire with Digital Cinema. The smaller holes also should be less visible from the front rows of seats (not that anyone should sit that close for today's Digital Cinema  ). The smaller area occupied by the MP perfs should be a bit more efficient for reflection. But substantial equalization is needed to compensate for the much greater high frequency sound attenuation. Kodak purchased a 25 x 64 foot Harkness Hall Matt White Plus MP screen for our projection lab in the 2000-seat "Theater on the Ridge" in Rochester, that is often used for "side-by-side" projection comparisons. We needed an efficient matte white surface designed for very close viewing. The new screen is installed "flat", and the frame is able to be "flown" for live stage shows. Lots of information on the Harkness Hall website:
http://www.harknesshall.com ------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
| IP: Logged
|
|
David Baum
Film Handler
Posts: 90
From: Brussels, Belgium
Registered: Aug 2000
|
posted 12-11-2000 07:08 PM
oops, was away, noticed so many posts and extended discussion thanks to Brad Miller. Very interesting. Was not such aware of the curvature and mat screens incompatibility.
Thanks John for the last post on the Harkness Hall. How close can you sit in front of the 0.5mm screen ? As stated, this is for my home theater (and I still have to get a reply from H Hall about the curving metallic structure they provide, absolutely no idea on the price).
Oh, if by any chance any of you guys go to Belgium, I recommand you visit the IMAGIBRAINE THX complex in the south of Brussels: very very well done complex, excellent sound, excellent images. only 10 theaters but really well maintained ( complex is new, maybe 3 years old or something ).
regards
PS: Hi John ! ( QSC ). btw, all Kinepolis group will switch to 100. QSC DCA amps.
| IP: Logged
|
|
|
|
|
|
|
|
David Kilderry
Master Film Handler
Posts: 355
From: Melbourne Australia
Registered: Sep 1999
|
posted 12-12-2000 05:50 PM
There are curved screens and then there are CURVED screens! Many of todays modern screens here have a very slight curve and use Perlux screens, the results are very good. MGM drive-ins here in Australia used giant 110ft plus curved screens at their twin drive-ins. The effect was amazing. (See Clayton page at www.drive-insdownunder.com.au) Until the late 1980's Hoyts still operated a few deep curved strip screens for Cinerama presentations (later 70mm stuff). These were built in 1969 in anticipation of D-150 and single lens Cinerama continuing. All you needed was a little bit of keystoning on a deep curve strip screen and a horizon shot in wide angle was all over the place. Still I recall seeing Star Wars and many other 70mm blowups on these screens and the results were pleasing - at least to a teenager. David
| IP: Logged
|
|
|
|
|
|
|
|
|
|
|
|
All times are Central (GMT -6:00)
|
This topic comprises 2 pages: 1 2
|
Powered by Infopop Corporation
UBB.classicTM
6.3.1.2
The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion
and agrees to release the authors from any and all liability.
|
Home
Printer-friendly view of this topic