Film-Tech Forum ARCHIVE: "World Trade Centre" in D-Cinema

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Posted by Ben Wales (Member # 92) on 10-04-2006, 04:17 PM:

Today I went to see the 9/11 film at the Empire Theatre in London with their 2k (Digital Cinema) DLP.

There were some dark scenes (under the rubble etc) that appeared to look like it was in Gray scale and lacked true black contrast.

It was quite noticeable and wondered is it also on the 35mm prints or is it just simply a Digital compression issue? [dlp]

Posted by Mark Gulbrandsen (Member # 72) on 10-04-2006, 09:08 PM:

quote: Ben Wales
It was quite noticeable and wondered is it also on the 35mm prints or is it just simply a Digital compression issue? .

The 35mm print I saw had great blacks and yes, it was a dark movie for the most part. D-Cinema cannot and probably will not ever be able to do complete black with the current imageing chip designs. The moving mirrors can only move 15 degrees I believe and there is going to be some light diffusion at the chip and in the optical train, so complete light cutoff to create true black is simply not possible. Also keep in mind that standard D-Cinema light level is 14fl and that cranking the light level up too high will wash out what black level there is even further. Proper screen illumination level with DC is very important. In NTSC video there are also no true blacks so one can almost think of D-C as having that similar set up level of 7.5 units like NTSC has. Its not really whats happenning but thats what the on screen result looks like.

Mark

Posted by Dustin Mitchell (Member # 372) on 10-05-2006, 12:56 AM:

Our digital print of 'World Trade Center' (Christie CP-2000 projector with Doremi server) looked fine. We aren't playing it anymore so I can't go back for another look unfortuntately but I watched it several times-especially some of the darker scenes-and never noticed that problem.

Any idea what brand of projector/server was in use? Screen size?

Posted by Ben Wales (Member # 92) on 10-05-2006, 03:31 AM:

quote: Dustin Mitchell
Any idea what brand of projector/server was in use? Screen size?

I belive they have a NEC (console size) and a Dolby server, the screen is about 55ft wide as it was enlarged recently.

The black levels were correct at the start of the movie with the cert titles and most of the day scenes, it was just the real dark scenes that suffered.

Posted by Caleb Johnstone-Cowan (Member # 3710) on 10-05-2006, 09:41 AM:

It's probably the Christie one mentioned above, all digital cinemas in the UK seem to have that one from the Arts Council who funded the rollout.

Posted by Bobby Henderson (Member # 840) on 10-05-2006, 09:46 AM:

I have a hunch the problem may really be in the lamp configuration of the projector. 55' is pretty large for a standard 4K or 6K digital projector. When screens get into giant size territory a projector model such as a Christie CP2000-X with twin 6K lamps would be more appropriate.

Posted by Mark Gulbrandsen (Member # 72) on 10-05-2006, 07:41 PM:

quote: Bobby Henderson
When screens get into giant size territory a projector model such as a Christie CP2000-X with twin 6K lamps would be more appropriate.

Actually it would be a massive waste! The NEC 2500 is hands down the most efficient of all the D.C. projectors available today. It is capable of ell over 23,000 lumens on up to an 85 foot screen with the reccomended NEC Lamp... not just in tests but in real life! The 2500 is rated for screens fomr 49 feet to 85 feet... Just imagine pixels as large as your house on that 85 foot screen!

It can do with a 4kw lamp what the others typically do with a 6kw lamp. NEC made huge strides in the optical chain of their projectors leaving both Barco and Christie in the dust. In many applications you don't need to use the special DC Lamps... you can use regular cinema xenon lamps. In fact the NEC is approved for all applicable Osram and Christie Lamps. The Christie projector is also but not for as many of the cinema related lamps as the NEC.

Mark

Posted by Bobby Henderson (Member # 840) on 10-05-2006, 08:05 PM:

Here's what I see as a customer:

Every single commercial theater I have visited over the last decade featuring a giant screen with 35mm projection has had an unacceptably DIM picture. Every one of them.

IMAX theaters seem to be the only giant screen theaters anywhere capable of an acceptably bright projected image.

Going by all of what I have read about digital cinema, it seems the DC projectors require more powerful lamp houses to get the same level of projected brightness as their 35mm counterparts. If that is the case, then how in the world is a 4K lamp supposed to properly light a giant sized screen?

Frankly, I think a lot of the people selling hardware and coming up with the technical copy in the brochures are over estimating just what their product can do. There is a long standing practice of simply doing things "good enough." That's certainly the case when it comes to brightness levels in non-70mm giant screen auditoriums.

Posted by Mark Gulbrandsen (Member # 72) on 10-05-2006, 09:28 PM:

quote: Bobby Henderson
Going by all of what I have read about digital cinema, it seems the DC projectors require more powerful lamp houses to get the same level of projected brightness as their 35mm counterparts. If that is the case, then how in the world is a 4K lamp supposed to properly light a giant sized screen?

That is true of both the Christie and Barco. But NEC decided to design their own optical train and it is more up to date and a more efficient design overall. The T.I. optical block that everyone else uses is actually a pretty old design. Yes, the NEC can easily do 23,000 lumens but it can also quite easily exceed that and in reality it can do nearly 30K lumens with the largest lamp it takes and over a very long period of time. You also have to remember that the D.C. spec is 14 fl and not 16. You would find that in an average case of a theater with a 28 to 30 foot wide glo type gain screen that the model 1500 NEC projector and a 3K lamp would work well. The 2500 is really for 49 foot or larger screens runnig 4K or larger lamps. Bobby, there are NEC projectors running in SLC and they do run just as bright as the Barco but with smaller lamps. Also the NEC can maintain the brightness for dfferent formats by preset lamp levels and also automatically adjusts the lamp level over its usable life to maintain the 14fl or what ever preset constant level you want.

The main thing both the Christie and NEC projectors allow the use of the less expensive standard cinema lamps. The special D.C. Lamps required to get maximum efficiency out of a given projector are quite expensive by comparison and have a pretty short life span. Cinema lamps by comparison last much longer and are much less expensive.

Mark

Posted by Jack Ondracek (Member # 1466) on 10-06-2006, 12:23 PM:

quote:
Just imagine pixels as large as your house on that 85 foot screen!

When NEC demoed their projector at the Transit Drive-In, I walked right up to their screen... specifically to look for those "house-sized pixels"... and saw none... not even the oft-described "jaggy lines".

I still have some reservations about picture quality... at least given what they showed us that night, but there's no question that the machine can light up a big screen pretty darn well. I'm hoping to get my hands on a USL meter some time soon. I still think I have a brighter setup here... but it's only conjecture right now.

They were pushing around 7,000 watts through the NEC, and to me, the picture seemed to have a "gray" feel about it. I don't remember how blacks looked, if I even noticed it at the time, whether it's related or has to do with something else.

Posted by Mark Gulbrandsen (Member # 72) on 10-06-2006, 02:35 PM:

quote: Jack Ondracek
the picture seemed to have a "gray" feel about it.

What ever they ran it must have been MPEG and not JPEG 2000(Joe's favorite). The feeling I got watching a comparison between the two at Dolby's screening room was that MPEG had a lifeless flat look to it whilst JPEG 2000 difference approximated the difference between a bad Eastman job and good I.B. Technicolor.

Mark