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Author Topic: Digital 3D Flicker
James R. Hammonds, Jr
Jedi Master Film Handler

Posts: 931
From: Houston, TX, USA
Registered: Nov 2000


 - posted 02-20-2008 08:05 AM      Profile for James R. Hammonds, Jr   Email James R. Hammonds, Jr   Send New Private Message       Edit/Delete Post 
I noticed a strange strobe-like flicker during the 3D portions of Hannah Montana the other day, but only in the 3D portions.
The 2D portions look fine.
If you take off the glasses, it looks as if the two images are shaking back and forth.
Does anyone know what causes this?
I've only recently come back into the business after a few years out and know next to nothing about the digital machines.

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Frank Angel
Film God

Posts: 5230
From: Brooklyn NY USA
Registered: Dec 1999


 - posted 02-20-2008 10:58 AM      Profile for Frank Angel   Author's Homepage   Email Frank Angel   Send New Private Message       Edit/Delete Post 
Nothing to know, James....they are designed to be foolproof and perfect so that any idiot can work them. If anything goes wrong, you need to call in that $250-an-hour service tech to fix it. And besides, you must be mistaken....only film has a shaking image, not digital. [Wink]

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Stu Jamieson
Jedi Master Film Handler

Posts: 524
From: Buccan, Qld, Australia
Registered: Jan 2008


 - posted 02-20-2008 02:29 PM      Profile for Stu Jamieson   Email Stu Jamieson   Send New Private Message       Edit/Delete Post 
Is it a twin projector 3D setup? If so, it sounds like the convergence between the projectors is off kilter causing image separation.

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Mike Renlund
Film Handler

Posts: 70
From: San Francisco
Registered: Feb 2008


 - posted 02-20-2008 03:53 PM      Profile for Mike Renlund   Email Mike Renlund   Send New Private Message       Edit/Delete Post 
That, or if its Real D, maybe the z screen isn't working correctly.

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James R. Hammonds, Jr
Jedi Master Film Handler

Posts: 931
From: Houston, TX, USA
Registered: Nov 2000


 - posted 02-20-2008 05:34 PM      Profile for James R. Hammonds, Jr   Email James R. Hammonds, Jr   Send New Private Message       Edit/Delete Post 
Sorry, I forgot to post specifics in my original post.
I wasn't given a detailed rundown of the equipment and I haven't looked at a manual yet, but I'll do the best I can.
The projector is a Christie DLP and it is Real D.
It does have the screen that goes in front of the lens which I assume is the Z Screen Mike mentioned.
I don't know much beyond that.

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Mark J. Marshall
Film God

Posts: 3188
From: New Castle, DE, USA
Registered: Aug 2002


 - posted 02-20-2008 05:37 PM      Profile for Mark J. Marshall     Send New Private Message       Edit/Delete Post 
There's an off chance that you've noticed that the eyes on a single projector system are in fact not in sync.

But then you aren't supposed to be able to see that, so I don't know.

I'm interested to see where this thread goes.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12550
From: Annapolis, MD
Registered: Dec 1999


 - posted 02-20-2008 07:14 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
Convergence on the projectors should not cause a flicker but it would cause eye strain.

It sounds more like a sync problem or perhaps the system was put into a 48Hz mode instead of the "triple-flash" that is the most common. At 144Hz, you shouldn't see any flashing.

Steve

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Ken Lackner
Phenomenal Film Handler

Posts: 1891
From: Atlanta, GA, USA
Registered: Sep 2001


 - posted 02-20-2008 08:53 PM      Profile for Ken Lackner   Email Ken Lackner   Send New Private Message       Edit/Delete Post 
I agree with Steve. Sounds like it is not set for tripple flash. However, it is rather odd that this would just start occuring, and therefore this begs the question, has this problem always happened on all 3D shows in that house?

In any case, it is best to have a qualified service technician take a look, as there is not much you can do about it if that indeed is the problem.

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Ken Lackner
Phenomenal Film Handler

Posts: 1891
From: Atlanta, GA, USA
Registered: Sep 2001


 - posted 02-21-2008 07:48 PM      Profile for Ken Lackner   Email Ken Lackner   Send New Private Message       Edit/Delete Post 
For poops and grins, I tried a little experiment this morning. I copied the Flat 3D format and saved it as a new format (so I wouldn't eff something up on the real format). Then I went into the 3D settings and changed the frame rate ratio from 6:2 (tripple flash) to 1:1. I ran Hannah in this format. Sho 'nuff, this created exactly the conditions James describes. Very noticeable flicker with glasses on, and a rapidly weaving (for lack of a better term) image with glasses off. This is because the projector is alternating between the two images slowly enough that the brain can perceive the changes, whereas with tripple flash, the alternation occurs so rapidly, your brain perceives it as a single image. (I hope I explained that clearly enough.)

So, if something is set incorrectly in your projector, and it was not like that for previous 3D features, or previous showings of Hannah, I am very curious as to what caused it. My first instinct was to suggest that the wrong format on the projector was selected, because 2D formats would not have tripple flash applied. But if you try to play 3D content in a 2D projector format, the colors will not look right. Since you did not report strange colors (which, IMHO, is more severe of a problem), I am assuming that did not occur. So I wouldn't think the problem was just having the wrong format selected on your projector.

Please keep us updated.

[Confused] [Confused]

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Tim Reed
Better Projection Pays

Posts: 5244
From: Northampton, PA
Registered: Sep 1999


 - posted 02-22-2008 11:50 AM      Profile for Tim Reed   Author's Homepage     Send New Private Message       Edit/Delete Post 
Yes, you have to have it set for 6:2. At nearly anything less than that, you can see flicker with the naked eye.
quote: Frank Angel
you need to call in that $250-an-hour service tech to fix it
Humm, I don't get anywhere near that much! Who has these jobs?

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Darryl Spicer
Film God

Posts: 3250
From: Lexington, KY, USA
Registered: Dec 2000


 - posted 02-22-2008 02:50 PM      Profile for Darryl Spicer     Send New Private Message       Edit/Delete Post 
If this is something that has worked fine on other 3-D features but just started giving problems with the Hannah feature then it could be an issue with the server or how the program is set up. There were specifics for setting up the program on the Hannah show because they switched to a different file format for the 3-D. Not sure if you are using the Doremi server but a program patch was available for the server when they Sent out the original keys. If you are an Access/it client then they were supposed to take care of that for you. Make sure that you have the 48 fps setting within the program set up.

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