Film-Tech Forum ARCHIVE: Is 6 fL the new de-facto 3D standard already?

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Posted by Antti Nayha (Member # 4980) on 07-18-2012, 09:28 AM:

I was just going through Disney’s projection docs, and it looks like their 3D light level spec has been raised from 4.5 footlamberts to 6.0. That’s what they’ve put in their documents at least since John Carter last winter (I couldn’t find a doc for Cars 2), I’ve just been slow to notice since I didn’t run JC.

Apparently Disney is not one of the studios who distribute several DCP's graded for different light levels? I may be poorly informed about this, since around here we only ever get one 3D version - most of the time with no instructions regarding light levels, save for the ones you may find on the web.

I heard that Marvel ran into problems last year when Thor was graded for 4.5 fL, because too many auditoriums just couldn't reach that in projection. This is why they decided to grade Captain America for 3.5 fL. I guess it's usually better to err towards a lower light level when grading, even if some venues are going to project your film brighter than that. Lowest common denominator, and all that.

But now, just a couple of months later, Disney has decided to raise their spec to 6 fL. Where exactly is the logic in that? [Confused]

Don't get me wrong, I'm all for higher light levels for 3D. But the lack of standards is frustrating - not to mention never receiving the higher-graded DCP’s, even when your auditorium could easily do 9 fL or more...

Posted by Monte L Fullmer (Member # 2797) on 07-18-2012, 12:48 PM:

The 6FL isn't for all of the digital units out there.

If you shoot 6FL in a projector set for 4.5, the pict will look dull and lifeless.

6FL is color timed for the brighter image since it has more contrast than the standard 4.5FL

Posted by Antti Nayha (Member # 4980) on 07-18-2012, 01:53 PM:

Yeah, I know... but is Disney still distributing 4.5 fL versions in addition to the 6 fL ones? As you can see at the link above, their tech sheets only mention 6 fL now. And as far as I know, they have never mentioned multiple DCP versions for different light levels.

As a sidenote, I happen to think that any image projected at 4.5 fL will look dull and lifeless.

Posted by Joris Springer (Member # 4175) on 07-18-2012, 05:20 PM:

However, as long as you get 4.5FL you will still be compliant to the DCI standard and that is what matters to them right?

And well, if you want to live by their documents that demand a lamp that still has a lifespan of 500 hours left then you don't want to play that in a theater that has a 6K or higher lamp in the projector.

Seriously, when do they make up their minds?

Posted by Mike Blakesley (Member # 26) on 07-18-2012, 08:23 PM:

All those documents are just feel-good stuff. Nobody reads them, but it makes the studio feel good that they've written them.

As for the 6fl thing....any studio would be crazy to master to "only" 6fl, considering they would obsolete about 97% of all the digital screens in the world in the process. I haven't looked at the paperwork but I assume the distributor either knows hardly anyone reads those things and just wrote that for the few places that have the 6fl projection OR they goofed. Probably the latter.

Posted by Monte L Fullmer (Member # 2797) on 07-19-2012, 03:27 AM:

I have four houses w/ 6FL capability. Someimes you get two seperate drives for each format, but lately, a 1TB drive that contains all three files will arrive.

Posted by Antti Nayha (Member # 4980) on 07-19-2012, 04:02 AM:

quote: Joris Springer
However, as long as you get 4.5FL you will still be compliant to the DCI standard and that is what matters to them right?

The DCI spec has no word on 3D light levels, which is part of the problem I guess. Anyway, even the new Disney spec states an "acceptable range" of 4.5–6.5 fL. (When the spec was 4.5 fL, the acceptable range used to be 3.5–5.5; sometimes 4.5–5.5.)

Don’t worry, I’m not living by their documents. Even though we don’t get the high-brightness DCP’s, I’m still projecting all 3D at up to 6–7 fL if possible, because it just looks so much better.

Monte: Do you get the different grades for Disney films, too? And what’s the third file (in addition to 4.5 and 6 fL)?

Posted by Monte L Fullmer (Member # 2797) on 07-19-2012, 12:43 PM:

quote: Antti Nayha
And what’s the third file (in addition to 4.5 and 6 fL)?

The standard 2D file.

Why we have the lower FL on 3D is so that it hides the ghosting of the dual image.

Posted by Antti Nayha (Member # 4980) on 07-20-2012, 05:11 AM:

quote: Monte L Fullmer
The standard 2D file.

Ahh, of course, sorry.

We’re not using those [bs]

passive polarization 3D systems in Finland anyway, so no ghosting problems here no matter how bright you go.

Posted by Frank Angel (Member # 248) on 07-22-2012, 12:13 PM:

Do studios check any of this stuff, anyway? Any theatres ever have a title pulled because they didn't have the right light levels? Does Disney check to make sure the hours left on a bulb in any particular theatre meets their hours left "requirement?" Hardly. Like Mike says, it's all mastabatory nonsense. Just part of the studios' "we want to control everything" culture.

I found this interesting: This document is not an endorsement of dual projector 3-D systems. On the contrary, Walt
Disney Studios Motion Pictures discourages the use of these systems. We believe that one of the most significant benefits and opportunities afforded by digital cinema technology is single
projector 3-D.

Single projector 3-D systems provide constant alignment, light levels, color, and focus for each eye. Dual projector systems create the risk of variation in each of these elements delivered to each eye, which can cause eye strain. Single projector 3-D systems eliminate this risk."

Single projector 3D systems also eliminate half the light level!

So I take it Disney won't play their titles in digital IMAX theatres? Are they are saying digital IMAX 3D sytems produce eye strain?

Posted by Steve Guttag (Member # 268) on 07-22-2012, 02:32 PM:

In terms of the 6fL MaxBright versions...A technician is supposed to sign off and submit a form that states that the light level can be achived (6fL in the center with the lamp set no higher than 75% (new lamp) power to ensure that it can maintain the 6fL for the life of the lamp.

So if the tech cares about his/her reputation, they won't sign off on such a thing...I know I haven't. Then again, I try to design my systems for better brightness anyway.

Posted by Monte L Fullmer (Member # 2797) on 07-22-2012, 02:37 PM:

quote: Frank Angel
Are they are saying digital IMAX 3D sytems produce eye strain?

...and/or, in general since it's not a natural presentation?

Posted by Frank Angel (Member # 248) on 07-22-2012, 05:43 PM:

Well, IMAX dual projection 3D certainly is a lot more "natural" than single projector 3D. IMAX dual projector has both eyes on the screen at the same time; all the others have each eye being temporally staggered which is a lot more unnatural, not to mention straining to see an underlit picture isn't exactly good for the eyes either. Dual projection wins in that catagory hands down.

Then as I have said before, any exhibitor who so desires can easily do dual projection 3D; no one is stopping anyone from installing a second digital projector other than the perhaps the cost. I guess it's all about whether or not an exbibitor is embarrassed enough having to present an image that once had a standard of 16ftL on their screen to one of where the standard was lowered to 4.5ftL, and then saying with a straight face that 4.5ftL looks fine.

I can never understand this reasoning. Here's the benchmark, but we can no longer meet it, so let's just change the benchmark. 16ftL is the standard to meet, not because someone decided it's a nice number, but because that's the brightness necessary for an image on a movie screen where the picture looks natural, detail is all there, etc. If 4.5ftL was the light level where the image looked natural and all the detail was there, then THAT would have been the spec to meet, but it's not. So now along comes 3D and with that system can't even come close to meeting the 16ftL spec. What to do? Change the spec to whatever the system can manage. I think it's folly. Why have specs at all?

Can't get your RTS curve to match the Dolby X-curve? No problem. Just redraw the curve to match what you can get, call it the New Spec and everyone's be happy.

Posted by Steve Guttag (Member # 268) on 07-22-2012, 10:12 PM:

First...for digital it is 14fL, not 16fL. The 16fL was heavily influenced by the flicker of the shutter as being the maximum tolerable with a typical dual-wing (or double speed single wing).

14fL is supposed to represent the same brightness that film has at 16fL when running clear, exposed film...or perhaps just a bit brighter (there is much debate in the tech world as to just what the equivalent brightness is...considering one is depending on the human eye/brain to do the integrating of the double flash of a film projector).

There is a long precedent on changing specs based on achievable results. Drive-Ins have never been able to hit 16fL and if you read the SMPTE spec...it does read like hand waving exercise. That is...the target is this, but since you can't hit it, it is this but you'll be fine if you only hit this.

In truth, standards are suppose to represent what is achievable, not just what is desirable.