Projector brightness

[Nate Yolles]

To properly evaluate your work, whether it be still slides or moving pictures, it would seem necessary that your projector be set at the correct level.

 

So, I break out my light meter and my color temp meter and I measure. But what levels am I looking for? I think I remember 16 footlamberts, but I'm not sure. As for color, should the projector be balanced at 3200?

 

Now as I type this, I realize that you can always project a grey card & color chart and compare to the actual charts. I'd still like to know the correct levels.

[Rob Belics]

John Pytlak has an article on this on Kodak's website. It's under the Cinematography tab or do a search for his name.

[Nate Yolles]

http://www.kodak.com/US/en/motion/newslett...d=0.1.4.9&lc=en

[John Pytlak RIP]

Thank you.

 

Standard SMPTE 196M specifies an aim of 16 footlamberts, with an allowed range for theatres of 12 to 22 footlamberts. Remember, the screen is part of the system, so you need to measure light REFLECTED from the screen (footlamberts) with a spot meter, NOT just light incident on the screen (footcandles).

[Nate Yolles]

Mr. Pytlak has a nice section over at Kodak.com, but I don't think I saw anything about proper color temperature.

[John Pytlak RIP]

Standard SMPTE 196M-2003 assumes the use of a xenon arc projection source:

 

For 35- and 70-mm prints, the light reflected from the screen in theaters shall have a spectral distribution

approximating that of a blackbody at a color temperature of 5400 K + 600 K -- 200 K, the use of short-arc

xenon light sources being assumed. For review rooms, where color matching is more critical, projectors shall

have a chromaticity match, for the same film format, of x = ± 0.002 and y = ± 0.004. For laboratory use in

color timing, projectors shall have a chromaticity match of x = ± 0.001 and y = ± 0.002. Typical chromaticity

readings would be D5500: x = 0.332 and y = 0.347. Chromaticity measurement

requires a precision chromaticity meter, not a color temperature meter.

[Ram Shani]

hi

 

i have the sekonic 508 which has only T STOPS how mach 16 footlambert is in Tstops in let's say 500ASA?

ram

[Wendell_Greene]

Set your spotmeter to 100asa @ 1/50. With the projector running point your meter at the center of the screen. You should get a stop of 3.2 (2.8 and 1/3) which is equal to 16 footlamberts.

[John Pytlak RIP]

Remember that a meter that can only read with an accuracy of 1/3 stop will have a hard time measuring the difference between 12 and 16 footlamberts:

 

http://www.kodak.com/US/en/motion/newslett.../june2000.shtml

[Sam Wells]

More of an issue might be whether your spot meter can read discontinuous sourcse properly but having said that I've done it with Minolta M & Sekonic 778 and I think I've gotten close enough for an educated eyeball evaluation.

 

More variation screen to screen in typical exhibition venues (for better or worse <_< )

 

I've always meant to contact Sekonic & ask what the're acceptance window is (dunno if they'd tell me....)

 

-Sam