Film-Tech Forum ARCHIVE: Real D glasses

This is topic Real D glasses in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by John Wilson (Member # 269) on 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?

Posted by Mark J. Marshall (Member # 1409) on 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.

Posted by Mark Gulbrandsen (Member # 72) on 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

Posted by Mark J. Marshall (Member # 1409) on 06-14-2009, 11:38 PM:

What the heck is elliptical polarization?

Posted by Julio Roberto (Member # 4976) on 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.

Posted by Monte L Fullmer (Member # 2797) on 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

Posted by John Wilson (Member # 269) on 06-15-2009, 02:33 AM:

Thanks guys...great info. [thumbsup]

Posted by Mark J. Marshall (Member # 1409) on 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?

Posted by Jack Theakston (Member # 4484) on 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.

Posted by Mark J. Marshall (Member # 1409) on 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.

Posted by Jon P. Inghram (Member # 4125) on 06-16-2009, 02:18 PM:

Also, did you know people can "see" polarization of light?

http://en.wikipedia.org/wiki/Haidinger's_brush

Posted by Hillary Charles (Member # 769) on 06-16-2009, 03:54 PM:

If they were linear, you wouldn't be able to tilt your head without the image ghosting.

Posted by Jonathan Althaus (Member # 5042) on 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.

Posted by Julio Roberto (Member # 4976) on 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 [Razz]

Posted by Jonathan Althaus (Member # 5042) on 06-19-2009, 11:01 PM:

It went green during Coraline in 3-D, though. I will try the rotation thing tomorrow.

Posted by Phil Blake (Member # 2012) on 07-02-2009, 07:39 PM:

slightly off topic the real D guys are brilliant with supplying these glasses.
we ordered 10 cartons of them on Monday from USA and they were delivered on Thursday. I was amazed at this superfast service considering we are about a million miles from USA.

Posted by Mark Gulbrandsen (Member # 72) on 07-02-2009, 08:04 PM:

How the heck are you going to use thos ein conjunction with a Kalee 21?

Posted by John Wilson (Member # 269) on 07-02-2009, 08:08 PM:

He puts them on while he changes the carbons on the run.

Posted by Mark Gulbrandsen (Member # 72) on 07-03-2009, 03:52 PM:

Yea, hopefully he's doing that with about 5 pairs of them stacked!

Posted by Ron Curran (Member # 3631) on 07-04-2009, 02:07 AM:

We're showing films in CinemaScope: The modern miracle you see without glasses!

Posted by Phil Blake (Member # 2012) on 07-04-2009, 07:27 AM:

quote: Mark Gulbrandsen
How the heck are you going to use thos ein conjunction with a Kalee 21?

well the man on the phone said they would work just fine ......... [Confused]

we have got a real d installation going in next week NEC projector with a CUBE. still hanging onto the film projectors .

ps the Kalee pic is quite old, must update.