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Author Topic: Auditorium Dimmer with LEDs Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 03-07-2017 10:28 AM                     Cree makes reliable dimming LED replacements Juno has a line of dimming LED potlights that get warmer as they dim and they are controlled by a 0-10v ddc control signal (max of 4 per control circuit and they follow sq law curve But they are not cheap  |  IP: Logged Justin Hamaker Film God Posts: 2253 From: Lakeport, CA USA Registered: Jan 2004 posted 03-07-2017 04:45 PM                        For everyone: Out of curiosity, do your auditoriums dim to 100%? We dim ours down to <5%,but want some light for safety purposes.  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 03-07-2017 05:35 PM                     0-100% Only during end credits we allow a little light. Of course we do have separate emergency lights, but they are very dim. - Carsten  |  IP: Logged Frank Cox Film God Posts: 2234 From: Melville Saskatchewan Canada Registered: Apr 2011 posted 03-07-2017 05:48 PM                        I dim my lights down to really dim, but not completely off. The fire inspector would not allow me to have the lights off completely.  |  IP: Logged Frank Angel Film God Posts: 5305 From: Brooklyn NY USA Registered: Dec 1999 posted 03-07-2017 06:17 PM                        In all our theatres we have three settings -- House level (about 85% -- we found it makes incandescent last MUCH longer than if we burn them full light output. Attraction Reel level (down to about 40%) Show level (as low as we can go but keeping the filaments still at a glow before they would go out) We have 6 rows of house lights each with between 60 to 100 as the they get progressively wider; from what I have seen of LEDs that are "dimmable," they do go out as noted, down to a low percentage, but that point is not fixed. If you got 10 of them together and dimmed them, they wouldn't all go out at the same time, so what I am batting around is the idea that perhaps the random nature of 500-600 of them jumping off randomly and not at the same time, that might actually give the effect of a smooth dim. Problem is, you would need to buy 600 LEDs test the theory. And then to complicate it more, we don't want them out -- we need there to be a glow which would probably be harder to get accurate and repeatable with that cut off point being so arbitrary from one LED to the next.  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 03-07-2017 06:48 PM                        I have never really thought much about auditorium lighting, but, thinking about it now, the typical cinema has at least five different lighting circuits in the auditorium: - "stage lights" or "screen lights" (or "curtain warmers")--light up the blank screen or curtain; these are often colored lamps; these are always at 0% during screenings - "ceiling lights"--typically PAR-type lamps in recessed fixtures or sometimes chandeliers; these are usually at 0% or just barely glowing during a screening and often come up to mid-level during trailers and credits - "wall sconces"--sometimes have two circuits, one of which dims to 0% during screenings and one of which either has very small lamps or otherwise is always on, but very dim--these are often at mid-level during trailers and credits - "aisle lights"--these are usually part of the seats or LED- or Christmas-light bulbs embedded in the floor along the aisles--these sometimes dim and sometimes do not, but are never very bright - "exit signs"--these always stay lit and, depending upon the placement, can cast an annoying red/orange glow on the edge(s) of the screen  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 03-07-2017 08:17 PM                     The only reason to have overhead lights "ghosting" is if you don't have your aisle areas sufficiently lit via other means (lamps in the seat standards, runway lights...etc.). There needs to be sufficient light such that people may enter/leave with what lighting is left during the show. I'd say that if one needs to leave the overheads on for any of the reason above, that it would almost be better to have separate lamps that are permanently on at the desired level (size the lamp, LED, preferably such that whatever requirements are met). Then let the overheads dim fully out. It is doubtful that anyone is going to get a completely uniform dimming action such that when those lamps are at 5-10% they will appear uniform. Not until such time that the industries abandon using incandescent dimmers to run lamps that are going into incandescent sockets. It makes no sense to me to not move away from traditional dimming/fixtures in favor of a purpose built LED system, particularly for plain old overheads (PARs). I think MIT has the right idea here with their ALFs...they just need to make it a dim to zero or smart enough that if the voltage drops below a threshold to automatically drop the lamp out.  |  IP: Logged Stephan Shelley Jedi Master Film Handler Posts: 854 From: castro valley, CA, usa Registered: Nov 2014 posted 03-08-2017 06:10 PM                     First off there are minimum required light levels and normally aisle lights and exit signs do not make these requirements. If someone gets injured while exiting in the dark the theatre can be liable. The Grand Lake has three color circuits in its lighting setup. Was originally for red, blue and yellow. My boss does not like blue so we have doubled up on the yellow. The reds are used as running lights and stay at a fixed level. The yellows go up and fully down with luxtrol dimmers. We have put in the cree bulbs with a colored rubber sock over them to get the color. Going down if smooth. but coming up from off they do tend to blink up and then come up the rest of the way. The red running we had to dim them down as they were much brighter at the preset we were using for incandescent. We have a couple that started blinking on and off. If you have incandescent on the same circuit the will end up being very low.  |  IP: Logged Manny Montes Master Film Handler Posts: 270 From: United States Registered: Feb 2010 posted 03-09-2017 01:02 AM                     We're required by city ordinance to leave a certain amount of light on, I forgot exactly what it is but its a certain measurement in lux measured from the floor. I explained to the fire inspector that its silly because the light reflecting off the screen along with aisle lighting would easily meet the level but it is measured with all lights off besides the overheads in a dark auditorium.  |  IP: Logged Frank Cox Film God Posts: 2234 From: Melville Saskatchewan Canada Registered: Apr 2011 posted 03-09-2017 11:51 AM                        I can see the point of not including the light reflected from the screen, since that light could go out during a show. And if the movie quits, that's exactly when a bunch of people will start getting up and moving around. "What's going on?" "Might as well get some more popcorn", etc.  |  IP: Logged Justin Hamaker Film God Posts: 2253 From: Lakeport, CA USA Registered: Jan 2004 posted 03-09-2017 06:43 PM                        The other issue with using reflected light from the screen is this can vary widely depending on the lighting during certain scenes. If you have a movie with dark lighting, it will be very difficult for people coming in from outside to see, and it will also be difficult for many older people who don't have sharp eyesight.  |  IP: Logged Frank Angel Film God Posts: 5305 From: Brooklyn NY USA Registered: Dec 1999 posted 03-11-2017 03:23 PM                        In NYC theatres are required to have lighting that allows patrons to clearly see all paths to the exits at all times and of course the exits must have exit lights as well. To my knowledge, the ordinance does not stipulated how you light the isle -- runner strips along the isles, isle down lights in the seat stanchion, overheads at a low level. I had seen the ordinance years ago and I don't think they gave a measurement in lumens or any other light measurement as to what that level is supposed to be; that certainly may have have gotten more specific over the years. In our big theatre we use both seat stanchion isle lights and house lights at a glow level. The small theatres just use seat stanchion lights. In cinemas, as opposed to other type of theatres or concert halls, the trick is to adequately meet requirements designed for safety yet not have that light degrade the screen image. I also found that there needs to be a way for that isle and foot step lights not to degrade the experience of the patrons well. I have now been in more than one cinema where the isle runner lights are placed in such a way that they will easily catch the eye of many patrons, especially those seated close to the isle. The effect of these little pinpoints of light constantly in the the corner of ones eye is about a thousand times more distracting than someone with an open cellphone screen. Now fiber optic isle and step lighting is available that is much less obtrusive than the multiple LED light strips. But even those should be of a brightness just enough to fulfill safety requirements and always with consideration of screen intrusion as well as patron distraction potential.  |  IP: Logged

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