He took a look at it and found there to be 15 ft lamberts on the scope image...a little under, but not too much. Still, it looked very dark so we decided to take a look at the others.
We found them all running in range from 16 to 22 ft lamberts, hence my thinking the new one was so dark.
But here's my question...is 16 ft lamberts really enough? Are we selling ourselves short by lowering the bar to accomodate theatres that simply can't (or won't) get anywhere near the correct luminence on screen?
The 22 screen was a bit bright and has been dropped a little (this would explain everyone touring the booth commenting on how lovely and bright the images were), but it actually looks great at 18/19/20 ft lamberts and pretty darn ordinary at 16.
Unfortunately, the lightmeter was worth $4000 so it's not like we will be buying one to check on them but I was truly surprised at just how ordinary an image at 16 ft lamberts looks.
I know the prints are made to run at 16, but do the producers actually think it to be enough or are they just putting up with a standard because they believe it untouchable to achieve a brighter image?
I'm curious...what do you guys think?
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"If you think THIS is fantastic...wait until you see the full effect with the HIMP projected at 19 ft lamberts!"
- Chief Inspector Clouseau (who, little as it was known, used to dabble in the booth from time to time).
I agree that image quality usually improves at higher screen luminance. Highlights sparkle, colors are more saturated, there is more detail in the dark shadows, and the prints even appear to be sharper.
But shutter flicker becomes more noticable at higher luminance -- with a two blade shutter at 24fps (48 interruptions per second), flicker starts to become very noticable at about 25 footlamberts. A higher frame rate could be used (e.g., Todd-AO 30fps, ShowScan 60fps), or a less efficient 3-blade shutter could be installed (72 interruptions per second at 24fps) to reduce shutter flicker. But the current standard is 24fps, and most theatres would be unwilling to double lamp power to compensate for the less efficient 3-blade shutter.
SMPTE 196M does allow a range of 12 to 22 footlamberts for theatres. At 22 footlamberts, perceived flicker with a two-blade shutter is still at an acceptable level. So why not use 22 footlamberts as the aim, since pictures will look "better"? The answer is that although the pictures may look "better", they won't reflect what the director and cinematographer intended as they made color timing decisions in the lab screening room at 16 footlamberts. You may see detail in the shadows that they did not want you to see. The more saturated colors may not reflect the pastel look they were seeking. Or scenes that were slightly underexposed would have "smoky" shadows as more light was visible in the shadows.
Dim screens below 12 footlamberts definitely produce INFERIOR images. But although screen luminance much higher than 16 footlamberts may often look "better", it may not reflect what the director and cinematographer intended.
You might ask why not raise the aim above 16 footlamberts, so movies are timed at a higher level, say 22 footlamberts? The problem is that most theatres are already below 16 footlamberts, and would then be even farther away from the aim.
Lowering the aim below 16 footlamberts is unacceptable, because of the many known disadvantages of low screen luminance, and the adverse effect making "thin" prints has on image quality.
So for now, the aim is 16 footlamberts, and theatres should try be be as close to it as possible, within the allowed range of 12 to 22 footlamberts. If you have 22 footlamberts, you are still within standard, and will have very good looking images. But the director and cinematographer may not want your audience seeing the villain lurking in the shadows, or colors that are brighter and more saturated.
Screen Luminance Article
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John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion
On a little screen the same is not the case 9fL looks horrible with whites turning into greys. Another factor in all of this is color temperture...some lamphouse manufacturers have high color temp reflectors (near or at 6000K)...this will be a bluer light and appear brighter (TV manufacturers do this too, by the way). 5400K is the standard for Xenon and films really do look better at 5400 than 6000K if they are timed that way...flesh tones practically jump out at you.
I recently set up a theatre and they have smaller screens (all 12 feet tall) and for scope we get 22fL...there is no objectionable flicker (single bladed shutters) and the pictures have a lot of "snap" to them...very sharp (good lenses too). The flat pictures are between 14 and 18fL (some have vertical masking, sorry the physical size of the theatre on four screens prohibited side movable, damn it). 14fL looks ok unless you compare it to a brighter picture (which the audience doesn't get to do).
One issue with bright (22fL) pictures is that the blacks start to turn other colors (grey or green mostly) as the lower limit of the film, as exposed, is reached. Also your masking better be jet black (velour or better!) because plain old Duevityne (sp?) will not hide any aperture shaddow well at that brightness.
I recently set up a lab...to answer your question, they have 16fL +/- .5fL anywhere on the screen and are filterd to 5400K. They can project 16mm, S-16mm and 35mm...the lamphouse is readjusted for 16fL in all modes. One of the tricks for obtaining balanced light between the formats (in theatres as well) is to use stop down rings on the more light efficient formats. For instance, if you have over 22fL on Scope but about 19 fL on Flat, try stopping down the Scope lens to f/2.4...the balance will be better an the focus will improve for the stopped down lens!
Steve
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"Old projectionists never die, they just changeover!"
quote:
Take IMAX for instance, they are lucky to get double digit brightness...many are at or around 8fL (2-D).
Huh? We average 24 fL (center) in 2D with a 15K lamp. Does the silver screen for 3D have that much effect?
Yup, and sometimes it isn't what the actors wanted either! Screen a print of the original Terminator movie over 20 fl and you'll see an awful lot more of Arnold than he wanted you to see! Same goes for Sharon Stone in Basic Instinct (of which was airbrushed out for the video transfer). I see this sort of thing all the time in a well lit auditorium, but the one that really takes the cake is the Terminator example. I understand this movie is being reissued. Wonder if they will digitally alter those scenes?
As far as the argument goes, my vote is to run as bright as possible before shutter flicker becomes an annoyance. Sure the filmmakers may time their prints for 16fl, but DAMN films sure do look good when projected brighter! Perhaps the most impressive recent film is Moulin Rogue. I screened this film in a large auditorium (putting out pathetic light) and thought it looked "ok". Then I saw it in a small auditorium with tons of light and my eyes were just glued to the screen!
The labs used to make special prints for drive-ins, wouldn't it be nice if they could make special prints timed at 22fl for theaters that have the power?
If you are a 3-D house then yes, the silver screen will have a 2X-3X effect on the brightness BUT you are only getting that in the center, the silver IMAX 3-D screens hot spot just like all silver screens not heavily curved. When I referred to 2-D IMAX, I was referring to Matte-White or very low gain white screens....It has been my finding that they are in the single digit luminance.
Steve
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"Old projectionists never die, they just changeover!"
I've noticed by the odd seating patterns in my theater that the larger screens (both Imax and conventional) seem to overwhelm folks who aren't ready for them. It may be that the size of the screen also has a certain effect on how one perceives brightness on that screen.
I recall a 35mm installation in Tulsa where the four big auditoriums had screens that were only perforated in front of the speakers. The rest of the screen was solid. Of course, the screens came folded, so I don't know if they were just cheap screens or if they were trying to accomplish something with brightness.
I just checked with one of my IMAX buddies...he said in his 3-D IMAX, they had between 24-28 fL in the middle with both 15K lamps (3-D mode) buring. That typical IMAX 2-D theatre are 8-12fL. Furthermore, some 2-D prints are specific to the theatre format...that is Fantasia 2000 was struck for 2-D and 3-D theatres (presumed timed differently) so the brightness looks proper.
Steve
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"Old projectionists never die, they just changeover!"
One of the things I really like about the SR system is that the PLC remembers where the lamps are supposed to be for 2D and 3D modes and will motor the lamps into the correct position so that you get 24fL regardless. Alas, the classic and GT aren't smart enough PLCs for that. My current GT gets 26fL in 2D and 16fL on each eye in 3D. Well, it did until someone else said it was too bright. 
Say, someone should make a smarter lamphouse that will adjust the lamp position automatically for flat and scope. Then again, big chains don't really care about what's on the screen anyway ... just so long as there's people in line at the snack bar. 
I suspect someone got a clue and figured out that perfs only cause problems in areas other than directly in front of the speakers. For example, I just sat through AI at one of the Muvico palaces where there was a specular 3 feet down from the top of the screen caused by a frame member that hadn't been blackened. Other than that, the film presentation was near perfect.
I curse perforated screens every time I run into this type of problem.
Christie has had their SLC console adjust the lamp between flat and scope for some time!
Steve
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"Old projectionists never die, they just changeover!"
Here are some links:
http://www.christieinc.com/reference.htm
http://www.christieinc.com/ultrafocus.htm
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John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion
Ideally, NO screen should have perf holes in it. What I find strange is that for years no company or sound technician has figured out that by limiting the thickness of the screen in small circles - say an inch in diameter or so - tweeter drivers could be glued to the back of the screen in these areas and provide a better sound than those trying to push sound through the screen.
Digital cinema in small auditoriums probably has it's own set of problems with perfs. If the lines of perfs don't exactly match the lines of the pixels a disturbing pattern might appear. If blended colors aren't used and a set of perfs happens to nearly match the pitch of the pixels, color shifts could occur.
Perhaps someone else knows if the AMC sucker screens used perfs only over the speakers?
Harkness Hall developed their line of MP (Mini-Perf) screens with smaller 0.5 millimetre perfs specifically to reduce the serious moire issue with digital pixels. As expected, there is more attenuation of the high audio frequencies.
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John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion
As for the Torus screens at AMC, all of the ones I saw had the speakers mounted above and below the screen.
If the screen, audience and projector are not in alignment, it may be difficult to obtain 16fl w/even screen brightness. We had a few screens at my old theater where this was true. I had to compromise because of this. 16 fl w/o even screen brightness, or 12fl with even brightness. I was not authorized to realign lamphouse and cut new plates. All I could do was report the problem. Even then, part of the problem was theater design architecture, and correcting that part of the problem was impossible.
Also keep in mind that if you bring the bulb too far forward in the lamphouse to increase screen brightness, then you can risk overheating and damaging the film and reflector mirror.
Some people also think that adjusting the current tap switch on the Christie SLC consoles will increase screen brightness. Not true. Forward and aft bulb adjustments for screen brightness only. Currrent tap switch used to ensure proper bulb current and to stabalize bulb as it ages. Remember that on the SLC lamphouses, that you cannot rotate bulb. Also, when making up, down, left and right adjustments on the Christie, then these adjustments will be the same for both flat and scope.
The information in my last post was given to me by Devon at Christie, as well as our Area Tech.
I did not notice any increase or decrease in screen brightness using the current tap switch on the Christie SLC.
Our Area Tech also informed me that bulb rotation on the Christie SLC console is not possible due to its design.
I was also informed about problems with Christies current tap switch, that the contacts are prone to burning/melting, and that the tap-switch was being set at the factory at the highest possible level, and being left alone. I was told that the bad tap switch design is another problem that Christie is looking into.