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Author Topic: Screen Gains and contrast Doug Woods Film Handler Posts: 2 From: Halifax, Nova Scotia, Canada Registered: Nov 2013 posted 01-30-2014 05:17 AM                        Hey there, not sure if this is the place to ask this question, however... I'm setting up a DI (digital intermediate) colour correction studio with a Christie Solaria One and I would like to get opinions on the best screen gain to achieve the best contrast. The throw is 25 ft to a 105 inch wide screen. I will be replacing the screen with a little larger one when I determine the most suitable materials. I currently have a 1.1 gain screen and the blacks feel a little washed out especially compared to the LED LCD monitors. I can achieve total darkness, except for my computer interface monitor. If anyone has experience with this I'd love to hear it. Thanks Doug  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 01-30-2014 06:05 AM                     The Solaria one is brightness, not contrast optimized. Black levels on all current cinema DLPs are not optimal, with the 1.2" models being the best in that respect and the S2k models being the worst. A gain screen will make it even worse. If you have enough brightness for your screen size, you may go with a matt grey screen surface (negative gain), and if possible you should use the lens in it's tele position, that is, place the projector the farthest away from the screen. - Carsten  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 01-30-2014 11:23 AM                     Christie offers high contrast lenses as well as a high contrast kit. I'm know Barco does not and I don't think NEC does either, but I'm not 100% sure on NEC. Go with the CP2215, get the kit and the high contrast lens. You will find the image is vastly superior to the typical result. I try and use high contrast lenses whenever I can, but on occasion where I've got light to spare I'll put the high contrast kit in as well. I've never done it in a CP2210/2215, but I believe that is an option.  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 01-30-2014 11:44 AM                     Well it seems that even the 'tuned' postproduction versions of the Christies and Barcos only achieve something like a 10-15% improvement in contrast/black level (at something like 50% less light efficiency). http://www.barco.com/en/Specsheets/32b82c40-301e-4c30-a650-fa1db2244d0c/DP2K-P.pdf That is near to nothing. And I wouldn't even start to think about a 4k: http://www.barco.com/en/Specsheets/9c7e0fc6-b4f3-4efc-bd34-4de6d1a38287/DP4K-P.pdf - Carsten  |  IP: Logged Alan Gouger Jedi Master Film Handler Posts: 501 From: Bradenton, FL, USA Registered: Jul 2000 posted 01-30-2014 12:16 PM                        Brad what is the Christie "contrast kit" comprised of. Nice to see them offer this. I took a Barco 4kP HC lens and replaced the factory iris with a more aggressive cats eye iris along with an aggressive iris in the light pipe just after the lamp house. I achieved 4000:1 maintaining uniformity. Most of the increase comes from the iris in the lens. The trade off is light loss, 40 to 50% but the increase in PQ is visually noticeable. If a laser retro ever becomes available those numbers may increase due to the nature of laser and its tight beam. I measured a Sony SRX515 over 8500:1 out of box, Minolta meter, impressive. PQ is vastly improved over the SRX320.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-30-2014 02:34 PM                     So you measured, with a 14fL center, on a checkerboard pattern, .001647fL or thereabouts? Forget the checkerboard pattern...you measure that with full on and then full off? What is the accuracy of your meter?  |  IP: Logged Alan Gouger Jedi Master Film Handler Posts: 501 From: Bradenton, FL, USA Registered: Jul 2000 posted 01-30-2014 04:20 PM                        Im using both a Photo Research "Cinebrate" for readings off the screen and Minolta T-10 for readings back at the projector.Yes full on/off is used. My clients have private screening rooms with complete light control to take advantage of any extra contrast.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 01-30-2014 06:26 PM                     If you want higher contrast, you should get a Sony 515. Contrast ratio is waay higher than DLP.  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 01-30-2014 06:42 PM                     And the new SRX-R510 is no more expensive even at 4k than the Solaria One. However, it lacks the necessary interfaces for a grading suite (2k/4k xyz only through DCP, only HDMI 1080p for external sources). The SRX-T615 would be better suited, but is waay more expensive (for no apparent reason ;-) - Carsten BTW - Marco, did you read my private message?  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-30-2014 06:51 PM                     I'm confused...you are using an incident meter to measure contrast ratio off of a screen? I guess you are holding the meter up to the screen, measuring full on and then measuring full black. The Cinebrate tops out at 1000:1 contrast ratio...and that is if you hit the center at 50fL. And it is all BS anyway...put up an alternating checkerboard pattern and see what you have.  |  IP: Logged Doug Woods Film Handler Posts: 2 From: Halifax, Nova Scotia, Canada Registered: Nov 2013 posted 01-30-2014 08:25 PM                        WOW, what an active forum. I love it. Thanks for all the suggestions. So I'm looking into the contrast kit for my projector as I have plenty of light to spare with the .3 ND filter and bulb at 59% to achieve a 14 fl reading. 2 important questions. 1 Do you know if screen manufacturers supply sample pieces, swatches, to test the various screen gains before you commit to a screen? 2 How do I embellish my "film handler" handle in my profile.  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 01-30-2014 08:46 PM                     You should be able to get sample pieces from the screen people, I have definitely seen them. Ask! The member rating/description is based on post count, I don't know how many posts are required for each level. Probably Brad can override that and even put oddball ones in if he wants, not sure about that though.  |  IP: Logged Alan Gouger Jedi Master Film Handler Posts: 501 From: Bradenton, FL, USA Registered: Jul 2000 posted 01-30-2014 08:58 PM                        The meter is place facing the lens close enough to get a solid reading between full on and off. Checker board is used to measure ANSI contras not on/off.  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 01-30-2014 09:01 PM                     quote: Alan Gouger Im using both a Photo Research "Cinebrate" for readings off the screen and Minolta T-10 for readings back at the projector. I guess Alans 'off the screen' means 'pointing the Cinebrate to the screen', reading screen luminance, while 'back at the projector' means he is holding the T-10 at the screen level pointing 'back towards the projector' reading incident light level on the screen surface. I first got it exactly the other way round... - Carsten  |  IP: Logged Alan Gouger Jedi Master Film Handler Posts: 501 From: Bradenton, FL, USA Registered: Jul 2000 posted 01-30-2014 09:09 PM                        Yes the PR takes its reading off the screen. The T-10 faces the projector usually a foot from the lens. You need enough light at 0ire to excite the meter. For best accuracy using an illuminance meter measurements between full on/off should be taken from the same distance to the lens.  |  IP: Logged

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