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» Film-Tech Forum ARCHIVE   » Operations   » Digital Cinema Forum   » Dolby 3D dual projector setups? (Page 1)

 
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Author Topic: Dolby 3D dual projector setups?
Carsten Kurz
Film God

Posts: 4340
From: Cologne, NRW, Germany
Registered: Aug 2009


 - posted 01-08-2010 04:43 AM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
I heard that recently two large screens in germany have been equipped with dual-projector Dolby 3D systems (Kinoton installations).

http://www.dcinematoday.com/dc/PR.aspx?newsID=1652

Someone mentioned to me that these projectors still contain Dolby wheels.
Is anyone familiar with this kind of installation, is it 'officially' Dolby approved? Why would they still use filter wheels inside instead of static 'Infitec/Dolby' filters in front of the lens? The only reason I could imagine would be that with filter wheels, both projectors could still be used as single 3D machines temporarily on smaller screens without reinstalls.
However my source mentioned that these would not contain standard Dolby wheels but special versions. Still I would think that static filters offer slightly more light - at least if these wheels still have segments and need blanking times.

Has anyone heard of Dolby providing static filters for projectors at all? Are they that much different from Infitec Filters?

- Carsten

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Demetris Thoupis
Phenomenal Film Handler

Posts: 1240
From: Aradippou, Larnaca, Cyprus
Registered: Apr 2001


 - posted 01-08-2010 05:12 AM      Profile for Demetris Thoupis   Email Demetris Thoupis   Send New Private Message       Edit/Delete Post 
There are two ways to implement a two projector setup. In both cases the desired result is to increase the light output on big screens.

One case is to use both projectors showing both eyes. In this case you are mentioning, most probably both projectors are flashing both eye images inside them and thus using the dolby filter wheel prior the light engine. The other case is where each projector shows one eye only thus having projector 1 showing left eye, and projector 2 showing right eye. That is where you use a static filter but I am not sure in Dolbys' case if its inserted prior the light engine or in front as I have never done such a setup myself. Most probably Mark or Gordon or Julio or Steve can inform us better.

Demetris

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Mark Lensenmayer
Phenomenal Film Handler

Posts: 1605
From: Upper Arlington, OH
Registered: Sep 1999


 - posted 01-08-2010 07:32 AM      Profile for Mark Lensenmayer   Email Mark Lensenmayer   Send New Private Message       Edit/Delete Post 
They ran 4-Barco projectors (2 for each eye) using Dolby 3D at the Empire Leicester Square theatre for the premiere in London. Don't know if they are still using them or not.

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Carsten Kurz
Film God

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From: Cologne, NRW, Germany
Registered: Aug 2009


 - posted 01-08-2010 08:11 AM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
Yes, 4 DLP+Dolby 3D for the AVATAR premiere there.
But only for the premiere I heard, afterwards they stayed with a 2 projector setup.

- Carsten

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Chase Taylor
Expert Film Handler

Posts: 175
From: Troy, Alabama, USA
Registered: Mar 2001


 - posted 01-08-2010 10:06 AM      Profile for Chase Taylor   Author's Homepage   Email Chase Taylor   Send New Private Message       Edit/Delete Post 
I believe but could be wrong but when using a BARCO DP-3000 in a dual projector set up the color wheel that goes into each projector is one filter that spins so basically the wheel is not split into two filters just one and each projector has the filter for one eye and the other projector has the filter for the other eye.

Someone please correct me if I'm wrong but I think this what I remember how it's done with those.

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Pete Naples
Phenomenal Film Handler

Posts: 1565
From: Dunfermline, Scotland
Registered: Feb 2001


 - posted 01-08-2010 12:35 PM      Profile for Pete Naples   Email Pete Naples   Send New Private Message       Edit/Delete Post 
That is my understanding too Chase, a static filter wouldn't stand up to the heat.

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Demetris Thoupis
Phenomenal Film Handler

Posts: 1240
From: Aradippou, Larnaca, Cyprus
Registered: Apr 2001


 - posted 01-08-2010 12:40 PM      Profile for Demetris Thoupis   Email Demetris Thoupis   Send New Private Message       Edit/Delete Post 
rotating filter with single eye filter

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99


 - posted 01-08-2010 03:14 PM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
I am pretty sure dual projector uses the exact same filters. You have two controllers and one just has to phase them both correctly.
Mark

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Kevin Fairchild
Expert Film Handler

Posts: 125
From: Kennewick, WA, USA
Registered: Oct 2008


 - posted 01-08-2010 06:39 PM      Profile for Kevin Fairchild   Email Kevin Fairchild   Send New Private Message       Edit/Delete Post 
Dolby has the Large Screen 3D installation instructions on dolbesecure.com

It says that there are two seperate filters.
Cat # 932 is the left eye filter.
Cat # 933 is the right eye filter.

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Sam D. Chavez
Film God

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From: Martinez, CA USA
Registered: Aug 2003


 - posted 01-08-2010 08:33 PM      Profile for Sam D. Chavez   Author's Homepage     Send New Private Message       Edit/Delete Post 
Kevin is correct.

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Demetris Thoupis
Phenomenal Film Handler

Posts: 1240
From: Aradippou, Larnaca, Cyprus
Registered: Apr 2001


 - posted 01-09-2010 01:40 AM      Profile for Demetris Thoupis   Email Demetris Thoupis   Send New Private Message       Edit/Delete Post 
After reading thoroughly via the Dolby Extranet, it says that they are static filters although they implement colour wheel like the standard solution so they are placed again prior the light engine. The BIG difference is that the images are not flashed at all as they are shown without any gaps as each projector shows one eye only so the brightness is much higher.
Demetris

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Kris Verhanneman
Expert Film Handler

Posts: 182
From: Belgium
Registered: Dec 2009


 - posted 01-09-2010 06:33 AM      Profile for Kris Verhanneman   Email Kris Verhanneman   Send New Private Message       Edit/Delete Post 
Much higher? How long do we project 'black' between a flash of image? Anybody who can say how much (%) that is?

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Julio Roberto
Jedi Master Film Handler

Posts: 938
From: Madrid, Madrid, Spain
Registered: Oct 2008


 - posted 01-09-2010 07:14 AM      Profile for Julio Roberto     Send New Private Message       Edit/Delete Post 
Aprox. 7%

Per projector.

So in this case, they get a 14% increase in light, compared to fitting both projectors with traditional filters.

Of course, having two projectors already "doubles" the light output to begin with.

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Mark Gulbrandsen
Resident Trollmaster

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From: Music City
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 - posted 01-10-2010 03:22 PM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
I never thought of that aspect. Either would work but one is going to give lots more light.

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Mark Uhde
Film Handler

Posts: 9
From: Kalispell, MT USA
Registered: Jul 2009


 - posted 01-19-2010 12:53 AM      Profile for Mark Uhde   Author's Homepage   Email Mark Uhde   Send New Private Message       Edit/Delete Post 
Sorry Julio, that math is wrong. You can't add the light loss from each projector to get the total. You have to average it. Since each one is, by your numbers, losing about 7% the average is also about 7% of the total.

To demonstrate why you can't add it, imagine a hypothetical 15-projector setup. If you added up the 7% loss in each projector to get total loss, you would be losing 105% of your light [Smile]

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