Film-Tech Forum ARCHIVE: Unusual projection problem

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Posted by Thomas Pitt (Member # 4322) on 03-29-2018, 02:14 PM:

I went to see Ready Player One today, but the auditorium seemed to have a strange issue with its projector. The bottom half of the screen was fine, but the top half had a 'double vision' effect, as if the image was being projected twice but out of alignment. It's a bit like when you see a 3D movie without glasses, but odd that it was only affecting the upper half of the screen.

The problem persisted through the trailers and even when the system went into 3D mode (with scope lens) for the actual movie. The 3D effect still worked, but after a while the double-vision became very distracting. I was told they were having some issues with the projector and couldn't fix it, not even by restarting the system - so everyone went out to get a refund.

Any ideas what could have caused this?

Posted by Ken Lackner (Member # 1002) on 03-29-2018, 03:11 PM:

Do you know what type of 3D system the auditorium uses? This sounds like a misalignment of a Real D XL. If that is the case, the theater should contact their service technician to fix the issue. If the theater doesn't use Real D, it is still almost certainly an optical issue, not an electronic one, and rebooting the projector would not fix it.

Posted by Carsten Kurz (Member # 5396) on 03-29-2018, 03:40 PM:

Whenever you see something like that, you should inquire right away what kind of projection and 3D system they use.

- Carsten

Posted by Monte L Fullmer (Member # 2797) on 03-29-2018, 07:33 PM:

Wonder if the location uses Sony Twin Lens and one of the RealD polarizer panels went out of alignment....

Posted by Randy Stankey (Member # 64) on 03-30-2018, 07:43 AM:

Isn’t it possible to infer the type of 3-D system by looking at the glasses?

For instance, holding two pairs up together and turning them to see which way the polarization of each lens goes?

Dolby should be a gimme. Right?

Posted by Thomas Pitt (Member # 4322) on 03-30-2018, 03:09 PM:

It is indeed a Real-D system (I have not seen Dolby at any UK theaters yet). It looked like there was a Z-Screen in front of the projector but again, can't be sure. The double image affected both the 2D adverts/trailers and the actual 3D movie.

Posted by Frank Cox (Member # 6258) on 03-30-2018, 03:44 PM:

If it's a Z-screen then the problem is likely a ghost image that's being reflected between the Z-screen and the port glass. I had that issue; the fix was to tilt the Z-screen vertically such that the ghost image is projected on the ceiling instead of the screen.

Posted by Jason Metcalfe (Member # 5739) on 04-03-2018, 08:39 AM:

Could also be incorrectly configured ghostbusting, like someone calibrated it from a single point in the room