Like many theaters, we are using slide projectors to show ads during intermissions. We use projectors with 250watt bulbs.

Over the past few years, we have been repeatedly asked to turn down the house lights so the ads can be seen easier. We do ... then a patron trips, complains they can't see, and the lights get put up again.

The real problem is, of course, the projector lamp is too small. I keep trying to explain: if we use a 3000 watt lamp to light a screen for a movie, why would anyone think something 12 times smaller would look just as good?

Since the ad company is not going to buy better projectors, this cycle could go on for a long time.

The fire code of your area will specify the amount of light required for safety in your 'enclosed area' situation. Most architechtural firms have a 'code compliance' expert on staff or available to them. This is a great place to start looking for information. Asking the local fire inspector, generally, is not a good idea as it sends a message of insecurity which the inspector will feel compelled to correct.

The lighting you should have in place for walking during a performance should be adequate during the slide show with only minimal additional 'house light'. The code will require some level of lighting so that the audience can find and safely use the exits without house lights and without light reflected from the image on the screen. These lights may be "EXIT" panels over the doors and walk lights on the aisles. Either runway lights or lamps in the end caps of the chairs should be present to make exiting safe in an emergency.

With regard to the 'brightness' of the slide projector image, the size of the film image is larger than that in the motion picture projector. Almost 3 times more area than the image size of the 1:85 projector mask. The lens of the motion picture projector is very "fast" having an F 1.9 or so light passing capability. Some slide projectors for home use have F 3.5 lenses. Check the F of the lens in your slide projector. You can get more powerful lamps for the slide projector. At the Temple Theatre we have a Xenon slide projector with an ORC 500 lamp. This machine with an F1.2 lens produces a credible image of 23' height in the auditorium lighted for moving pictures.

Another issue is the amount of 'house light' which is being directed toward the screen. Careful control of the spill from ceiling fixtures can minimize the 'wash out' of images on the screen. This control of spilling light is also helpful in assisting the audience to leave during the credits. Especially during credits with outtakes, some of the audience will stay while the others will bolt for the doors making this a particularly dangerous situation for the audience and could foster complaints from those who wish to enjoy the outtakes.

KEN

 |  IP: Logged

 |  IP: Logged

Thanks for the readout on the Canadian code. Could you tell me all of what the code says about that light level? I think there is something in there about where the level is measured, like at the floor or 4 feet above the floor and is that the absolute minimum or is that the average reading?

If you wanted to use lights in the end stands of the chairs, could they be as here in the US? We can have an average of 4 foot candles of light at the floor level in aisles and walkways. That means a 15 watt frosted lamp located 21 inches above the floor and spaced at 8 foot intervals from opposing sides of the aisle. These are often called 'walk lights' as well as aisle lights.

 |  IP: Logged

Thanks for the data. It appears that the isles in Canada must be brighter than here in the USA. At least in Michigan.

 |  IP: Logged

During intermissions and between shows, we run the house lights at walk-in level. I think that is very close to what Gordon said. About 8 foot-candles. It is a comfortable level, not too dim and not too bright.

The LED projectors we use for ads provide enough foot-lamberts on the screen where our customers don't complain about the auditorium being "too dark."

There are some advertizing firms that will install and maintain the projectors and will pay a pre-determined percentage of what they charge the clients to post the ads on your screen. It may not be much, but it is something.

If you find a company that will do that for you, it is best that you have a technician on site so those technicians from the the advertizing company do not screw up you sound racks or sound systems with their audio interface.

Most of those I have seen will admit they don't know Shit from Shinola when it comes to the high-tech theatre sound systems, and will welcome the assistance and directions from the theatre technicians.

Of course, you will find a couple who "know it all." I tangled buttholes with one like that, and I kicked him out of the booth. His boss dropped in to finish the installation and to un-screw what his technican screwed up. When he was done, he apologized like there was no tomorrow.

 |  IP: Logged

Removing the slide projectors is not an option! They do generate serious $$, and no one (especially now) are going to give that up.