I'll say 16 fl is about right. The SMPTE has specific standards for light output in theaters.
The issue with xenon lamps in movie theaters is that a new lamp puts out much more light than one that has a thousand hours on it.
Back in the good old days
http://www.avsforum.com/ubb/wink.gif when carbon arc was the standard, a properly adjusted lamphouse always delivered a consistent brightness to the screen.
When we first started using xenon lamphouses, and we had real projectionists
http://www.avsforum.com/ubb/wink.gif , we would start a new xenon lamp at a lower amperage and gradually increase the amperage as the bulb aged to make up for the reduced light output that was a result of the bulb's envelope darkening.
Today, unless you live in LA or NY, all bets are off regarding the proper setup of most theaters.
Too much light is as bad as too little, causing visible flicker on bright scenes and poor black levels.
However, the problem in many theaters is light spill on the screen from exit signs and other external sources. Many theaters also leave the house lights on at a very low level, or have wall sconces on at a low level, because after all no one wants to be sued by a patron who trips or otherwise injures him/herself.
I feel that I have better light control in my home theater that most commercial theaters have.
Vern
http://members.home.net/tvdias/