Film-Tech Forum ARCHIVE: 3D

This is topic 3D - 2D flexibility in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Lennart Gabrielsson (Member # 6474) on 10-13-2011, 03:37 PM:

Hi we are currently configuring our remaining screens (170 of 240) for digital cinema. Our current digital installations have until now only been showing 3D. We will now start showing 2D and 3D and runs in to the problem of changing lamps due to the big difference in light demand.
We are aiming for 3D in 9fL at 80% of the lamp max power and 2D at 14 fL.
Has anyone a good setup for switching between 2D and 3D without having to change the lamp?

Posted by Steve Guttag (Member # 268) on 10-13-2011, 09:34 PM:

Lennart,

The truth of the matter is...no...there is no good way to use the same lamp between 2D and 3D...particularly if one has side movable masking (Scope is bigger than flat)...the difference in the light requirements are just too large. A xenon lamp that has been running at 90-100% to handle 3D will not run stably down at 50-60% for 2D.

That said, most folks are indeed having one lamp do for both.

Your target numbers are off. 9fL is too high for 3D...the movies are not timed for that high and you will find that the blacks turn to gray. They are timed with the presumption of a nominal 4.5fL +/- 1fL. If you have a silver screen, you should go much higher than 14fL for 2D...that 14fL figure only applies if you also have 12fL at the sides of the screen...which a high-gain screen will not achieve. You'll want the light in the lower 20s.

-Steve

Posted by Carsten Kurz (Member # 5396) on 10-15-2011, 07:35 AM:

Lennart - what projector, what bulb, what 3D system, what screen do you use?

- Carsten

Posted by Lennart Gabrielsson (Member # 6474) on 10-15-2011, 05:20 PM:

We are using Barco, Christie and NEC in different sizes all with MasterImage or RealD on silver screens.

Posted by Olivier Lemaire (Member # 5579) on 10-16-2011, 12:36 PM:

dual projectors settings?

This way you can have shinny 2D and 3D. Master Image dual glasses costs far more than the usual rotative block.

Posted by Mark Gulbrandsen (Member # 72) on 10-16-2011, 05:49 PM:

If you are going to do just an occasional week or two long show in 2-D get your self a sheet of Rosco Neutral Density Gel. It is optically and neutrally perfect and one sheet gives you a dozen or so filters to use up. For longer use contact Century Precision Optics and buy an appropriately sized glass ND filter. You can easily base your filter requirements by taking a simple light reading with the Master Image lowered all the way below the light path. These filters are made every 1/4 stop generally up to 2 stops... sometimes more. This is a very elegant dolution that has worked well. You can even set up an extra pair of Macro buttons and make it color corrected. Oh and be sure to remove the filter before you go back to 3-D... you don't want to have your on screen image looking like you're at an AMC.