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Author Topic: Preferred screen brightness Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 04-08-2019 01:53 PM                     Whereas this was a discussion in an SMPTE meeting some years ago, I'm not able to present that information here. Even with Film projectors of yesteryear and decent lenses, and a matte-white screen, it was certainly possible to exceed the Standard. I also never favored lumping corners in with sides...they are completely different in terms of lighting.  |  IP: Logged Emerson Caitano Film Handler Posts: 1 From: Rio de Janeiro Registered: Nov 2016 posted 04-08-2019 02:40 PM                     I prefer to work with 21 FT, similar to IMAX  |  IP: Logged Harold Hallikainen Jedi Master Film Handler Posts: 906 From: Denver, CO, USA Registered: Aug 2009 posted 04-08-2019 02:45 PM                        The SMPTE standard does not "lump in corners with side." There is a separate specification for corners and sides. However, for theaters, the tolerance on corners is open. It is specified for sides. On preferring higher luminance than the movie was created for, it seems like it may be preferable to some individuals, but not the movie creator. The movie creator may have wanted to do 21 fL for peak, but there's no standard for that (but I guess IMAX uses that throughout). The HDR draft from DCI allows for a peak white of over 140 fL though it is not necessary to use that. It's up to the creator. Harold  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 04-08-2019 04:37 PM                     You're getting into semantics. For review rooms it states "sides and corners" with a single percentage reading applied to both. Though it is "at least" type number (can be higher) the realities are, if the corners are included, that is where the darkest area will be, presuming even light distribution. I'd have to check but I think the Theatre Luminance limits used to be similarly worded as the Review Room Luminance limits, if one went back far enough.  |  IP: Logged Bobby Henderson "Ask me about Trajan." Posts: 10973 From: Lawton, OK, USA Registered: Apr 2001 posted 04-08-2019 08:50 PM                     How does foot lambert levels convert over into nits? The reason I ask is because of LED boards and how their brightness levels are rated. For example, Samsung's new LED signage & cinema screen products list one or two nit levels in the product specs. The boards for The Wall claim nit levels of 1600 (peak) and 500 (max). The boards in the Onyx product line are 400 nits. Both products are for indoor-only use. FYI, outdoor LED boards must be much brighter to compete with ambient sunlight. The Daktronics LED displays our company sells can have max brightness levels up to 12,000 nits.  |  IP: Logged Harold Hallikainen Jedi Master Film Handler Posts: 906 From: Denver, CO, USA Registered: Aug 2009 posted 04-08-2019 09:04 PM                        A nit is 1 candella per square meter. 1 fL is 3.4262591 nit. Multiply fL by 3.4262591 to get nit. Harold  |  IP: Logged Marcel Birgelen Film God Posts: 3357 From: Maastricht, Limburg, Netherlands Registered: Feb 2012 posted 04-09-2019 05:39 AM                     As a reference, Dolby Vision content can be mastered to up to 10k nits per pixel, there is currently no projection technology that comes close to this though. Some top of the bill OLED screens are seemingly capable of producing up to 8k nits, but I'm sure you're going to burn them out rather quickly if you keep pushing them at those extremes.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 04-09-2019 08:09 AM                     Note: Checking some documents...S196 (film) lumps sides/corners as a single specification in review rooms and specifies just sides for theatres. 431-1 (D-Cinema) does indeed separate them out in separate categories but to the same effect (same specification for both in review rooms and "not specified" for Theater when it comes to corners. In short, the result is very similar but I think the 431-1 is more clear in its presentation (chart). S196 is more brief in its presentation (just text). S196 doesn't put an upper limit on sides/corners like 431-1 does.  |  IP: Logged Harold Hallikainen Jedi Master Film Handler Posts: 906 From: Denver, CO, USA Registered: Aug 2009 posted 04-09-2019 11:46 AM                        Thanks for checking on the standards! Also, it's interesting that for film, "peak white" is 16 fL since it is "gate open" with no film. It is assumed you lose about 2 fL due reflection and attenuation by clear film. Harold  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 04-09-2019 01:24 PM                     It was more sophisticated than that. The goal was to simulate lowest density of processed film. If you were to photograph the sun, lets say and process that...what would the throughput be. I can't say for sure if or who did this but I know that was the goal in matching the two. Unfortunately a great resource from those days is no longer with us (John Pytlak).  |  IP: Logged

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