|  IP: Logged

10 foot high screen

(10 x 10) x 12 = 1200 watts.

 |  IP: Logged

Note that by Pat's formula, the largest 35mm screen that can be adequately lit with even a huge 7000 watt lamp is 24 feet high. Theatres installing 30 x 72 foot screens will have dim pictures or burned film.

No. Drive ins usually just run with low light. A 40ft high screen would be about 95ft wide; that's pretty big!

Some drive in projectors have "fast pull-down" intermittents (allows the shutter to stay open longer) to get more light. But nothing is going to light that screen. 35mm film just can't take that kind of light (heat.)

In reality, any screen larger than about 25 x 60 feet will be difficult to light to the SMPTE aim of 16 fL without risk of heat damage to 35mm film. A 70mm print allows spreading the energy of the lamp over a much larger area of film, so huge screens are much easier to light properly with 70mm formats. If you have a 30 or 35 foot high screen, the only way to light it properly is with a 70mm print.

------------------
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

As Pat notes, many theatres have screens that use poorly chosen lamp sizes. For example, to reduce lamp inventory, some theatres routinely use only one or two lamp sizes for screens ranging from 10 x 24 feet(which only needs about 1200 watts) to 15 x 36 feet(which needs about 3000 watts) to 20 X 48 feet (which needs about 5000 watts) to 25 x 60 feet (which needs about 7000 watts). Or they try to economize by using a 2000 watt lamp for screens much larger than the 13 x 31 foot size that can be comfortably lit with 2000 watts.

The only sure way to know if you are meeting the SMPTE standard is to regularly MEASURE the screen luminance using a calibrated screen luminance meter. Here are several articles that I wrote on the subject:
http://www.kodak.com/US/en/motion/newsletters/reel/spring98/pointers.shtml http://www.kodak.com/US/en/motion/newsletters/notes/march2000/pytlak.shtml http://www.kodak.com/US/en/motion/newsletters/notes/june2000/pytlak.shtml

------------------
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

No, I actually have all the SMPTE Standards, Recommended Practices, and Engineering Guidelines committed to memory!

Actually, committed to my laptop's memory: I purchased the CD-ROM set from SMPTE that has Adobe Acrobat .pdf files of ALL current SMPTE standards. Here is the link:
http://www.smpte.org/stds/index.html

For as little as $250.00, you can be as expert (and fast) as me!

In Italy ARCADIA has the biggest european screen: 98 feet lenght. I've seen some films on that screen but It seems that there were no problem in luminance.
Pls note that ARCADIA is known in Italy as one of the best theater in the world.
The auditorium is THX certified, of course.
Just to say that it seem strange to me...

Bye
Antonio

 |  IP: Logged

------------------
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

John, seems like I remember some research done not all that long ago that determined (basically) the bigger the image, the less illumination was required to make the image effective. There was a train of thought saying that very large (appearing) images have so much visual information that it's overwhelming to the brain if it's illuminated at "normal" standards.

Are you aware of anything like this?