[mythtv-users] OT: 3D TV

Andre Newman mythtv-list at dinkum.org.uk
Mon Jan 11 18:34:09 UTC 2010


On 11 Jan 2010, at 18:20, Ronald Frazier wrote:

> On Mon, Jan 11, 2010 at 1:09 PM, Johnny <jarpublic at gmail.com> wrote:
>> Both of them only
>> let each eye see half the frames, but polarization reduces the
>> brightness further on the frames the eye does see.
> 
> I'm not sure about the polarizing tech they use for these films, but
> as a photographer I know that a polarizing filter typically reduces
> brightness by about 2 stops, which means only about 1/4 of the light
> gets through.

The cinemas that convert to 3D usually have to upgrade their screen to a higher gain (brighter) screen that scatters light a lot less than a regular one, that way more of the light retains it's correct polarisation. The projector lamp is upgraded too, I don't remember the wattage but 3 phase power is required!

The actual 3D bit is very simple, an LC panel that swings into place in front of the lens and plugs in to a spare IO port on the projector pedestal. Great fun ensues when the projectionist forgets to swing the panel into place :-)

As LCD projectors are already using polarisers as part of their function, many many years ago I modded a pair of NTSC LCD projectors by rotating the polarisers on one. Not very good separation though, the modern circular polarisation technique is much better.

Andre



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