Film-Tech Forum ARCHIVE: Auditorium cleaning light

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Posted by Frank Cox (Member # 6258) on 07-10-2019, 02:14 PM:

I have a 500w halogen light high on the back wall of my auditorium that I use while cleaning. Last night it came on much less brightly than it usually does, then went out altogether a few minutes later. Bulbs in that thing don't last long -- I only use it for ten or twenty minutes a night and it seems I'm changing the bulb every year or so.

Anyway, I went to change the bulb and discovered that it had got so hot the part where the bulb meets the base has welded itself together. Shucks.

This is either the second or third time that I've had this happen over the years. Every time I have just replaced the fixture with another of the same thing, but they sure aren't up to much.

This time I'm going to try a super-bright LED instead and see if that works any better. I walked around town this morning to see what's available here and nobody has anything like what I want so I'm going to order this:

SOLLA 100W LED Flood Light

Hopefully this will last longer than those halogen lights. Maybe it won't get so hot.

I guess I'll be doing the cleaning in the dark for a week or so until it gets here. If it turns out to be good I think I'll get a second one for a spare.

What do you guys use for cleaning lights?

Posted by Scott Norwood (Member # 30) on 07-10-2019, 03:45 PM:

I have seen this done a few different ways.

The standard multiplex approach is to use fluorescent tube fixtures above the seating area. These are bright and rarely require replacement, but the fixtures would look terrible in an historic auditorium. They really only work if you have a drop ceiling like the ones used in many offices.

In older buildings, the usual option is to have a large bare bulb in the ceiling (I've seen 1000w mogul-base incandescents used for this), or else a second set of (bright) bulbs (or higher dimmer setting) in the chandelier(s). Replacing the bulbs is not fun, though.

I have also seen fixtures like the one in in your link (the halogen version, though) mounted on the back wall or ceiling. These are unsightly, but seem to work well enough. I don't know about the bulb change intervals.

The worst arrangement that I have seen was a theatre that used metal-halide lighting (or something similar), which required a warm-up time measured in minutes, and which would not hot-restrike.

I suppose that all of this is to say that there isn't really a good option--only less-bad ones.

The only LEDs that I have seen used for this purpose are in a multi-use venue that uses them for house lighting.

Posted by Sam D. Chavez (Member # 1841) on 07-10-2019, 03:53 PM:

I would go bigger or get a couple. Does not sound very bright.

Posted by Bill Brandenstein (Member # 7758) on 07-10-2019, 04:59 PM:

Our facility where I work has spent six figures this year converting a great many halogen ceiling and spot bulbs to LEDs. Visually speaking, this has been wildly successful. The technology has matured to a point where brightness and quality are really impressive. You may find that this fixture, though spec'd to replace a 550W halogen, is considerably brighter than what you're used to. I look forward to reading your updates!

Posted by Randy Stankey (Member # 64) on 07-10-2019, 08:07 PM:

Halogen lamps need to get hot in order to work their best.

The heat allows metal vapor inside the glass envelope to reach equilibrium. If the lamp never gets hot enough it won't last as long as it should. It will still work. You just won't get the most out of it.

Stage lights are a good example. Halogen lamps inside stage light fixtures will last longer if they are turned on and left on for a longer time. Lights that are flashed on and off won't last as long. Some stage lighting control consoles have a "preheat" setting where lights are powered just enough to make the filaments glow slightly. That is supposed to allow them to stay warm so they come on quicker and last longer.

I would say that, in your case, a halogen light isn't the best choice if you want longevity. If you're only turning the light on for a short time a few times a day the lamp might be on long enough to get hot enough.

That might be one reason why you aren't getting the life out of your lamps that you think you should.

I think your idea about LED lights is a good one.

If you can find one that fits your needs I think you should go for it. [Smile]

Posted by Leo Enticknap (Member # 534) on 07-10-2019, 11:09 PM:

Shameless plug alert: our auditorium lighting fixture is designed to be a walkin/house light and a cleaning light in one unit. It does need low voltage DC and 0-10v for control, and so isn't a plug and play replacement if you don't have those services already in your ceiling, plus an appropriate dimmer. But it's very cost effective to install as part of a new build or major renovation.

Posted by Frank Cox (Member # 6258) on 07-10-2019, 11:29 PM:

One problem with a lot of light fixtures is that they are ceiling mounted. Which makes sense of course, but then they are too high for me to reach when a bulb needs to be changed. And having to pay an electrician for a service call to change a light bulb isn't something that I want to do.

Ceiling mounted in an 8-foot ceiling is one thing; ceiling mounted in a 16 or 20 foot ceiling is something altogether different.

I had the regular auditorium lights moved a couple of years ago for just that reason. They were originally mounted on the ceiling; now they're mounted on the walls at a height that I can reach from a reasonable ladder, but still out of reach of customers of course.

It's still a nuisance to drag a ladder into the auditorium to change a light bulb, but at least I can actually do it now.

Posted by Gordon McLeod (Member # 33) on 07-11-2019, 08:48 AM:

We have been using 2x4 led layin panels in most of new theatres and as a retrofit
The light from above tends to not have shadows that make cleaning and seat repair more difficult

Posted by Leo Enticknap (Member # 534) on 07-11-2019, 09:19 AM:

quote: Frank Cox
One problem with a lot of light fixtures is that they are ceiling mounted. Which makes sense of course, but then they are too high for me to reach when a bulb needs to be changed.

Agreed, and in the pre-LED days, this was a major problem. When I worked at the Egyptian, probably around a third of the auditorium lights were out, and were never going to come back on again until the next major refurb, for the simple reason that whatever genius architect was responsible for the 1998-99 renovation failed to take into account that light bulbs do not last forever - the Phoebus cartel won that battle!

The result is a number of light fittings in that place that simply can't be reached without some suicidally dangerous climbing. And so, of course, when they went out, they stayed out.

LEDs have solved a lot of that problem. Sorry again if this sounds like a sales pitch, but our Architectural Lighting Fixture ("architectural," as in, it should be considered a part of the fabric of the building) is designed for 50,000 hours of continuous operation at full power (which, in a regular movie theater setting, it would never be called upon to do), is an LED luminaire that is literally designed to last the life of the building - or at least, between major refurbs when access to the ceiling would be needed anyways.

Posted by Marcel Birgelen (Member # 6801) on 07-14-2019, 12:59 AM:

For what it's worth, our screening room uses two 30W LED floodlights of the Philips brand as cleaning lights.

For the size of the room, that's more than sufficient. Even one would be sufficient, but it helps to have some light from different angles while cleaning.

You need to be careful about many of the Chinese LED crap out there, because it's often badly designed and doesn't come close to what's advertised.

Posted by Buck Wilson (Member # 5885) on 07-14-2019, 07:58 AM:

quote: Sam D. Chavez
I would go bigger or get a couple. Does not sound very bright.

A 500 watt halogen puts out roughly 7000 lumens so the light he linked is brighter than he has currently(or had technically lol)

But if in doubt, MORE LIGHT! I love LED. You can really have an extraordinary amount of light for next to nothing. I have a hundred or so houseplants and I give most of them light via a track light setup with about 25 r30 flood spots. With a standard 65w incandescent flood in each it'd be over 1,600 watts and there's no way I'd be able to have it all on the same track let alone timer/circuit, etc. Not to mention just the lights alone would be $75/mo to power.

LED... 225 watts total, $10/mo.

Posted by Frank Cox (Member # 6258) on 07-15-2019, 04:15 PM:

Just finished installing my snazzy new light. It's pretty much the same as what I had before in terms of the amount of light that you get out of it.

The halogen light mounted onto the electrical box but this one has a wider bracket that screws to the wall. Then there's a couple of bolts that go through the bracket adjust the angle of the light, and about three feet of cord to go back into the box.

It still gets hot when it's running but nowhere near as hot as the halogen did.

I can't say anything about longevity yet, but so far it's just exactly what I wanted. And it's only 100 watts.

Posted by Terry Monohan (Member # 8285) on 07-17-2019, 09:28 AM:

I have had to track people down so many times to turn off the extra bright vapor cleaning lamps inside one of the XD spaces at the Century/Cinemark 9 in downtown San Francisco.

It was bad enough to sit thru all the boring pre show paid ads with bright white light from the cleaning ceiling bulbs not going off but when the trailers hit that is when I made the move to do something about It.

The few lame people in their seats just sat there and did nothing. Took about 10 minutes for a candy type person to shut them off. No dimmer just a cut off switch I guess. The audience would have just sat in their seats while the main movie was on I think If I did not look for someone.

This has gone on at least 4 times in the last year at this cinema. I think most theatres have a hidden wall switch that the clean up crew turns on and off. I will have to look for It next time this happens at a Century Theatre.

Just as bad as left on cleaning lights new cinema builders keep on placing the side wall white lights next to the screen and all the light shines onto the right and left sides of the screen during the trailers.

No more side wall color lights these days, just bright white light. Do any of these movie theatre design lighting people even care about all the stray light leaking onto the screen. If they only put the first fixtures way back from the screen.

I have got many theatre managers that know of this stray light problem to go in and put in smaller light bulbs close to the screen. Now with LED's this is hard to do If they are not dimmable.

Posted by Justin Hamaker (Member # 2165) on 07-17-2019, 02:51 PM:

We use a large LED on the building at our drive-in and it's pretty bright. I can't say how it will be inside since it's an outdoor space. However, I also have a CAT 10w LED work light and it illuminates spaces pretty well. I have to imagine a 1000w LED is going to work just as well as your halogen light.

Posted by James Wyrembelski (Member # 9037) on 07-17-2019, 04:18 PM:

We have 4 LED flood lamps in each corner of the auditorium.

Its not as ideal as having the lights directly overhead, but gets the job done.