If the distributor timed the prints lighter in hopes of compensating for theatres that had dim screens, they compromised the overall quality of the image. Making a print lighter will tend to compress the highlight detail, wash out the flesh tones, and make the blacks more "smoky". But since they accepted the "look" of the prints that way, and are recommending a lower luminance for showing them, I would comply with their request. But be sure to return to the standard 16fL luminance after the run.

To show why this philosophy is flawed, imagine taking the practice to the extreme. If theatres have dim screens, why not make the prints REALLY light? If you do, the film will be clear and have no image!

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John Pytlak, Senior Technical Specialist
Worldwide Technical Services, Professional Motion Imaging
Research Labs, Building 69, Room 7419
Eastman Kodak Company
Rochester, NY 14650-1922 USA
Tel: 716-477-5325 Fax: 716-722-7243

Theater owner: I need 20 consoles for my new theater complex. I want the best light on the screen I can get. All of them are 18ft x 45ft.

Equipment supplier: "Well, our "BlastLight 5000W" seems about right. That'll be $1800 each."

Theater owner: "At DarkStar supply, they told me that the Cataract 2000W's would work. It's $750 cheaper. See ya later....."

Equipment supplier: "Wait! I can supply the TotalEclipse 2000W's," (sigh) "for the same price."

Theater owner: "How good are they?"

Equipment supplier: "Well, they aren't as bright as....."

Theater owner: "Well, if they're no good..." (starts dialing cell phone.)

Equipment supplier: "I meant, uhm.. ah.. the PAINT on the outside is not as bright, yeah, that's what I meant..."

Theater owner: (Hangs up cell phone, but doesn't put it away.) "So I really don't need 5000 watts?"

Equipment supplier: (Eyes are on phone) "No, you don't really need it."

Theater owner: "OK then." (puts phone in pocket.) "Trying to up sell me, eh? Ha-ha, well, I'm an expert at that. So how good are these lamps?"

Equipment supplier: (Sighs) "Very good." (theater owner reaches towards pocket) "I meant to say, 'the best you can get.'"

Theater owner: "Good, that's what I want to brag to other owners at NATO. Give me some free logo T-shirts and baseball caps, too. Those consoles come with the bulbs, right?"

It also doesn't help that you need a $2200 meter to read brightness. When you can't get your boss to buy good quality splicing tape, how are you going to get a meter? Unless someone comes up with a cheaper way of mesuring reflected light, few people will even know how bad off they are.

Hey with a 12fL requirement, most theatres should be about right...it is the 16fL that they have problems with!

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With a 1.5 gain curved screen, figure about 4 watts per square foot. And about 3 watts per square foot for a 1.7 gain curved screen.

Obviously this assumes normal efficiencies for the lamphouse, shutter and optics. Any misalignment, dirty screen, three-blade shutter, etc. will require much more power. The effective f/stop of the projection lens is also an important factor, with a wider lens opening offering greater light efficiency, at the expense of depth of focus.

BTW, a 1000-square foot screen is 20.5 X 49 feet for the 2.39:1 scope format.

------------------
John Pytlak, Senior Technical Specialist
Worldwide Technical Services, Professional Motion Imaging
Research Labs, Building 69, Room 7419
Eastman Kodak Company
Rochester, NY 14650-1922 USA
Tel: 716-477-5325 Fax: 716-722-7243

For a 1.0 gain matte white screen, figure about 54 watts per square metre of screen area. So a 100 square metre (6.5 X 15.5 metres) matte white screen needs at least 5400 watts, so a 6000-watt xenon bulb is the smallest that will do the job.

Use at least 43 watts per square metre for a 1.5 gain curved screen.

Use at least 34 watts per square metre for a 1.7 gain curved screen.

Again, these "rules of thumb" are based on the Strong/IscoOptic "Lens Selector and Picture Size Comparator".

------------------
John Pytlak, Senior Technical Specialist
Worldwide Technical Services, Professional Motion Imaging
Research Labs, Building 69, Room 7419
Eastman Kodak Company
Rochester, NY 14650-1922 USA
Tel: 716-477-5325 Fax: 716-722-7243

Height of screen squared, times 12

exp: 20.5 ft screen sq = 420.25
times 12 = 5049 watts