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Author Topic: Real D glasses John Wilson Film God Posts: 5438 From: Sydney, Australia. Registered: Dec 1999 posted 06-14-2009 07:48 PM                     What sort of glasses are these...that is: what's the name of the polarisation? Will other glasses do the trick or do Real D have some sort of proprietory right to their make-up? Do anyone else but Real-D make them?  |  IP: Logged Mark J. Marshall Film God Posts: 3188 From: New Castle, DE, USA Registered: Aug 2002 posted 06-14-2009 08:17 PM                    They are circular polarized. Other companies make circular polarized glasses, I assume they work as long as they are oriented the same way. They even make clip on versions. The linear versions of the clip ons worked great at Jeff's 3D festival. Look here for one manufacturer.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 06-14-2009 09:37 PM                     Actually I was told that Real-D uses Eliptical Polarization... which is why their glasses don't work on normal circular polarized systems. Mark  |  IP: Logged Mark J. Marshall Film God Posts: 3188 From: New Castle, DE, USA Registered: Aug 2002 posted 06-14-2009 11:38 PM                    What the heck is elliptical polarization?  |  IP: Logged Julio Roberto Jedi Master Film Handler Posts: 938 From: Madrid, Madrid, Spain Registered: Oct 2008 posted 06-15-2009 12:33 AM                    The same thing as circular but the retarder film was rotated with respect to the polarizer film to some odd degree (instead of 45º angle) http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/polclas.html RealD can't hold patents or whatever for the glasses. You can get them made.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 06-15-2009 12:45 AM                     What's a bit fun is to have the glasses on and look at yourself at a mirror. With both eyes open, all looks sorta normal, but you can tell something isn't right. Close one eye and the opposite lens goes black. Take two glasses and put their opposite lenses face to face together and look though it. Looks normally. Rotate one 90* and both goes completely black. After studying that site above, it now makes a bit of sense of the usage of silver screens - to really reflect back that left hand twist of light to go right handed on return and opposite lenses see both twists. ...-Monte  |  IP: Logged John Wilson Film God Posts: 5438 From: Sydney, Australia. Registered: Dec 1999 posted 06-15-2009 02:33 AM                     Thanks guys...great info.  |  IP: Logged Mark J. Marshall Film God Posts: 3188 From: New Castle, DE, USA Registered: Aug 2002 posted 06-15-2009 12:41 PM                    quote: Monte L Fullmer Close one eye and the opposite lens goes black. Which is the opposite of linear glasses. Thanks for the info, Julio. That's an interesting site. Any idea why they chose not to make the elliptical polarization circular?  |  IP: Logged Jack Theakston Master Film Handler Posts: 411 From: New York, USA Registered: Sep 2007 posted 06-15-2009 04:07 PM                     The glasses, from what I understand, are the exact same linear polarizers, just not at the usual 45-degree angles as the usual variety. The circular polarizer is the projector filter.  |  IP: Logged Mark J. Marshall Film God Posts: 3188 From: New Castle, DE, USA Registered: Aug 2002 posted 06-15-2009 08:40 PM                    No, I know that's not true. The glasses are definitely elliptical (I originally thought circular, but I guess I was wrong on that) in nature.  |  IP: Logged Jon P. Inghram Expert Film Handler Posts: 124 From: Wichita, KS USA Registered: Jan 2007 posted 06-16-2009 02:18 PM                     Also, did you know people can "see" polarization of light? http://en.wikipedia.org/wiki/Haidinger's_brush  |  IP: Logged Hillary Charles Jedi Master Film Handler Posts: 748 From: York, PA, USA Registered: Feb 2001 posted 06-16-2009 03:54 PM                     If they were linear, you wouldn't be able to tilt your head without the image ghosting.  |  IP: Logged Jonathan Althaus Master Film Handler Posts: 435 From: Bedford, TX Registered: Dec 2008 posted 06-18-2009 08:41 PM                     If you look at a digital projection (such as preshow) on a silver screen thru the glasses backwards, it has a green tint to the picture. Disclaimer: I know absolutely nothing about digital cinema.  |  IP: Logged Julio Roberto Jedi Master Film Handler Posts: 938 From: Madrid, Madrid, Spain Registered: Oct 2008 posted 06-18-2009 11:47 PM                    quote: Jonathan Althaus If you look at a digital projection (such as preshow) on a silver screen thru the glasses backwards, it has a green tint to the picture. If the factor I'm thinking about is the one at play here, that's probably true only of pre-show projectors that are based on LCD (rather than DLP). LCD based projectors make use of polarized light to work. Thing is, their polarization (linear) orientation doesn't have to (and often does not) follow conventions for 3D (i.e. they can be 90º and 180º instead of 45º and 135º). And one of their 3 color panels, usually the green, has an orientation different from the other 2 (i.e. red and blue). When you put your circular polarized glasses backwards you sort of convert them to linear polarized (not really, but that's the short explanation as light enters the linear film before being rotated by any retarder). I bet that if you rotate them (while backwards) you'll no longer get a "greenish tint" (with that projector) but the tint will gradually change from green to magenta (red+blue) as you rotate them from 0º to 90º. You can fun with polarization like you did when you were in Physics 102 in High School  |  IP: Logged Jonathan Althaus Master Film Handler Posts: 435 From: Bedford, TX Registered: Dec 2008 posted 06-19-2009 11:01 PM                     It went green during Coraline in 3-D, though. I will try the rotation thing tomorrow.  |  IP: Logged

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