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Author Topic: Preferred screen brightness Kevin Fairchild Expert Film Handler Posts: 125 From: Kennewick, WA, USA Registered: Oct 2008 posted 04-05-2019 11:38 AM                     I know 14fL is spec, but I'm curious what brightness each of you think looks best.  |  IP: Logged Harold Hallikainen Jedi Master Film Handler Posts: 906 From: Denver, CO, USA Registered: Aug 2009 posted 04-05-2019 12:42 PM                        Since the studio mastered it for playback at 14 fL (48 cd/m^2), supposedly that would look best. Lower levels can cause darker scenes or portions of scenes to become invisible. Higher levels can make flicker more visible. Both higher and lower can affect the perceived color. Harold  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 04-05-2019 04:07 PM                     +1 on that.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 04-05-2019 05:38 PM                     +1 too with a * * - as long as 14fL is measured on an AVERAGE on screen. I found that on a high gain screen a centre value of around 23fL gives an average of 14fL (measured on 9 positions). Way too many times just the hotspot is measured, giving a dull picture on those high gain(even worse: silver) screens mounted on flat frames on short throw auditoria.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 04-05-2019 10:45 PM                     Well yeah. You have to follow the whole standard and not just cherry pick the convenient one.  |  IP: Logged Marcel Birgelen Film God Posts: 3357 From: Maastricht, Limburg, Netherlands Registered: Feb 2012 posted 04-06-2019 01:39 AM                     Something that "looks best" is a very subjective thing. I personally might consider a particular movie to be overly dark, unfitting to the tone of the movie, so I may think it "looks best" with a bit more brightness... But, as a tech, a projectionist or exhibitor, that's not really my task. My task would be to present it at the brightness it was intended to be screened. So, like others put it, you should present it at 14fl.  |  IP: Logged Kevin Fairchild Expert Film Handler Posts: 125 From: Kennewick, WA, USA Registered: Oct 2008 posted 04-06-2019 04:19 AM                     Thanks everyone. quote: Marcel Birgelen But, as a tech, a projectionist or exhibitor, that's not really my task. My task would be to present it at the brightness it was intended to be screened. So, like others put it, you should present it at 14fl I understand what you’re saying but I don’t entirely agree. In the case of audio, if I were to present the feature at the intended 7.0 volume, I would be bombarded with complaints that the volume is too loud. As an exhibitor, I believe your loyalty should be towards the customers’ preference, not the creator’s. I’d like to edit my original question: If you had your own screening room for your own personal viewing, where would you set your brightness to? Personally, I like the colors to be slightly on the vivid side so I tend to turn it up a little.  |  IP: Logged Marcel Birgelen Film God Posts: 3357 From: Maastricht, Limburg, Netherlands Registered: Feb 2012 posted 04-06-2019 08:15 AM                     We do have our own screening room. Still, I'm not able to answer your question, since it's highly dependent on the movie itself. I guess that for most movies, the overal brightness is just about fine. So, generally, I don't mess with the brightness, unless it's getting into such extremes, that it starts to irritate. I guess it's the same with the sound. I try to play it at "7.0", but some mixes are so hot, they get turned down a notch, because they're simply unbearable at 7.0. Maybe the director intended to blow my eardrums, but that's where I draw a line. Some mixes, I'd also consider defective. I have helped them a hand in the past, I must admit... (Interstellar, I'm looking at you now) Still, the general rule that you present the stuff it should be presented should apply. Customer complaints can be factored in, but I personally won't factor in the singular customer complaint, I'd rather try to educate them. I did the same back when I worked at a cinema, back when we still had actual film to run . If individual customers came by complaining the movie was too loud, too silent, too dark, too light, too black & white, I'd tell them that we always aim for a presentation the way it was intended to be presented and that, in this case, it was the director's choice it worked out that way. If we had hordes complaining about something being too loud or the other way around, then we generally tried to "fix" it, although even then, we generally tried to inform the public that we turned the volume down or up before the show started.  |  IP: Logged Daniel Schulz Master Film Handler Posts: 387 From: Los Angeles, CA USA Registered: Sep 2003 posted 04-06-2019 11:21 AM                        I like 14fL for regular movies that were graded for 14FL, but I've become very fond of the 21fL that IMAX has settled on. Their new projectors have enough contrast ratio to look really good at that light level, as they can still go dark when the material calls for it. As projectors get better and better I find myself wishing for SMPTE/DCI to revisit the luminescence spec.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 04-06-2019 04:36 PM                     If the projector has enough contrast ratio and it was my personal screening room, I’d set it to 20fL.  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 04-06-2019 04:48 PM                     Yup. You don't like an overly bright setting on e.g. an S2K machine, but with a better contrast, going higher doesn't hurt. - Carsten  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 04-06-2019 09:06 PM                     quote: Steve Guttag Well yeah. You have to follow the whole standard and not just cherry pick the convenient one. In my 20 years in the cinema industry I’ve never encountered anybody following that part of the standard.  |  IP: Logged Frederick Lanoy Film Handler Posts: 88 From: North of France Registered: Aug 2009 posted 04-07-2019 02:53 AM                     One day on a Barco DP4K40LHC (Laser High Contrast), I did a mistake and forgot to assign the correct laser dimming to Flat. So I used the same value for Flat and Scope which means Flat was too bright as it was a scope screen. The movie was "Shape of water" (1.85) and during my test, I notice how good the image looked. I was actually fooled by the High Contrast on the projector (both native and ANSI). When I measured once again the brightness on Flat corrected white (XYZ), I was close to 22 ft/l and it looked great on this specific example. I was almost sad to dim to reach 14 ft/l. Otherwise, target is 14 ft/l unless the content is graded for higher value. In France, we have Eclair Color that needs 30 ft/l. It can look good if the content is good.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 04-07-2019 05:34 AM                     Frederick Was that shown on a high gain/silver screen?  |  IP: Logged Harold Hallikainen Jedi Master Film Handler Posts: 906 From: Denver, CO, USA Registered: Aug 2009 posted 04-08-2019 01:04 PM                        SMPTE 431-1:2006 specifies luminance and chromaticity tolerances for theaters and review rooms. The reference value for the center of the screen is 48 cd/M^2 or 14 fL. For theaters, the tolerance is +/- 10.2 cd/M^2 or +- 3 fL. The reference value for the sides of the screen is 85% of center with a theater allowed 75 to to 90% of center. It's interesting that 100% of center is not allowed. There was considerable discussion of this at ISDCF regarding emissive screens which, I expect, would be pretty even. Further, if headroom is available, it should be possible with digital projectors to adjust the luminance of the sides up to 100% (or adjust the center down so it is the same as the sides). There was considerable discussion as to why the 85% value was there. Is it because that's what projectors were capable of, or is it indeed desired that the sides be dimmer than the center. There was discussion of a visual effect where the side suddenly drops to black (masking), and that a slightly dimmer side was desirable. I do not remember the name of this visual effect. For emissive displayes, it was finally decided that the radiation pattern of the LEDs (beamwidth) resulted in the sides being a bit dimmer than the center, though I have not seen measurements showing that they meet this specification. Further, if you were to measure from a non-center location (such as the left end of a row 2/3 back), the side of the image would be brighter than the center at this location. SMPTE is working on a recommended practice for screen luminance measurement that includes the center of the seating area, the left and right sides of the center, and the left and right sides of the front row. If the theater has a balcony, additional measurements are in the balcony. The goal is documenting the luminance at the ideal location (center of audience) and at several non-ideal locations. How is the image quality at these locations? Should they be within the tolerances specified by ST 431-1? On higher luminance, note that the draft at https://www.dcimovies.com/drafts/DCI-DRAFT-HDR-D-Cinema-Addendum_v09_2018-1116.pdf for high dynamic range puts peak white at 500 cd/M^2, or about 10 times the current peak white. https://www.dcimovies.com/drafts/DCI-DRAFT-Direct-View-Display-D-Cinema-Addendum_v09_2018-1116.pdf is a draft document on emissive screens. They are to support standard dynamic range (48 cd/m^2) and may optionally support HDR (500 cd/m^2). There is considerable discussion of off-axis performance. Finally, DCI release https://www.dcimovies.com/announcements/DCI-Technology-Evolution-Statement_2019-0329.pdf which describes the two above linked documents and also tells about viewer preferences. Harold  |  IP: Logged

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