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Author Topic: Soft Vertical Lines on Matte White Screen
Adrian Hauser
Film Handler

Posts: 44
From: Sydney
Registered: Mar 2008


 - posted 08-24-2011 09:18 PM      Profile for Adrian Hauser   Author's Homepage   Email Adrian Hauser   Send New Private Message       Edit/Delete Post 
HI All,
We have just installed a new Matte White Screen (Harkness MW Super) in our theatre.
When projecting a white test pattern I can see soft vertical lines running in the screen. (They are not hard creases but soft 1" think looking lines. )The lines appear brighter than the projected white plane. I can only see a couple of these lines at any time and they only appear at the point of reflection between my position in the room and the projector.

The screen has been hanging now for two weeks.
The lines do not change when I zoom the lens on the projector or push the focus on the lens. THe lines do not dissappear when I remove the post glass.
Projector DP2kP.

Could it just be 'soft' fold marks in the screen. or could it be something line an "end of roll" screen? Or something else.

Thanks,
ADrian

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Jerome Holmes
Film Handler

Posts: 35
From: San Jose, Ca
Registered: Nov 2008


 - posted 08-24-2011 10:35 PM      Profile for Jerome Holmes   Email Jerome Holmes   Send New Private Message       Edit/Delete Post 
This sounds like the seams for the screen. Each screen isn't really a solid piece, but composed of long strips fused together at their edges. I usually think its dimmer than other parts of the screen, but its possible that this area on your screen is devoid of perforations, resulting in more area to reflect light back (uneven with the distribution of perforations on the rest of the screen).

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Adrian Hauser
Film Handler

Posts: 44
From: Sydney
Registered: Mar 2008


 - posted 08-24-2011 11:44 PM      Profile for Adrian Hauser   Author's Homepage   Email Adrian Hauser   Send New Private Message       Edit/Delete Post 
Thanks Jerome,

We have a non perf screen.

Looking at our 5m in width screen (screening room) I could say that these vertical 'soft' lines appear in groups of 2s. The are 2 lines are about 15 cm apart occurring every 70 cm.

The more I look at it it looks like a soft fold mark.

Adrian

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Brian Guckian
Jedi Master Film Handler

Posts: 594
From: Dublin, Ireland
Registered: Apr 2003


 - posted 08-26-2011 06:56 AM      Profile for Brian Guckian   Email Brian Guckian   Send New Private Message       Edit/Delete Post 
I'm just wondering if your surface has sagged very slightly. Is the tension OK?

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Adrian Hauser
Film Handler

Posts: 44
From: Sydney
Registered: Mar 2008


 - posted 08-29-2011 03:37 AM      Profile for Adrian Hauser   Author's Homepage   Email Adrian Hauser   Send New Private Message       Edit/Delete Post 
Hi Brian,
We re-tensioned the screen last Friday. The lines are still there.

Hmmmm
Anyone?

Adrian

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Frank Angel
Film God

Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999


 - posted 08-29-2011 05:37 AM      Profile for Frank Angel   Author's Homepage   Email Frank Angel   Send New Private Message       Edit/Delete Post 
Time to talk to Harkness & tell them of the problem. I thought Harkness was famous for NOT having visible seams. And if it is not seams, then whatever it is, they need to make it better. Also, when you say "soft folds," was this screen shipped folded? I thought Harkness shipped their screens on rolls.

If you have determined it is not the projector (zooming and changing focus) then it has to be the screen or some weird reflections from other light sources. I would turn every light in the hall off, including booth lights and see if you detect any light spill on the screen from any other source. Walk up close to the screen and see if you can created a shadow of any kind. Also, what is behind the screen? Any possibility that light hitting it from the rear could be causing this light pattern?

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Alan Plester
Expert Film Handler

Posts: 209
From: great yarmouth england
Registered: Apr 2001


 - posted 08-29-2011 05:43 AM      Profile for Alan Plester   Email Alan Plester   Send New Private Message       Edit/Delete Post 
Sounds like the screen joins to me, we had the same trouble with one of our screens for years, drives you mad, we changed eventually.

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Frank Angel
Film God

Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999


 - posted 08-29-2011 07:08 AM      Profile for Frank Angel   Author's Homepage   Email Frank Angel   Send New Private Message       Edit/Delete Post 
I agree. But he's lucky; it's brand new. He should yell and scream to get Harkness to make good on their guarantee.

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Brian Guckian
Jedi Master Film Handler

Posts: 594
From: Dublin, Ireland
Registered: Apr 2003


 - posted 08-29-2011 08:15 AM      Profile for Brian Guckian   Email Brian Guckian   Send New Private Message       Edit/Delete Post 
Re. seams, note that Adrian reported that the lines are occurring every 70cm. Are seams that close together in this type of screen? I always thought they were spaced much further apart.

As Frank mentions, it would be good to know if the screen was shipped folded or rolled.

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Phil Ranucci
Expert Film Handler

Posts: 236
From: Carpinteria,CA, United States
Registered: May 2006


 - posted 08-29-2011 01:59 PM      Profile for Phil Ranucci   Email Phil Ranucci   Send New Private Message       Edit/Delete Post 
What's your screen frame made out of? We have one screen frame made on unisstrut that the installers didn't paint the joints so there is a reflection. Any chance the screen is being pushed out at the vertical braces?

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Adrian Hauser
Film Handler

Posts: 44
From: Sydney
Registered: Mar 2008


 - posted 09-02-2011 05:37 PM      Profile for Adrian Hauser   Author's Homepage   Email Adrian Hauser   Send New Private Message       Edit/Delete Post 
I recall the screen arriving in a folded package. Definitely not a Rolled package.
I'll contact harkness.

I will also attempt to take a photo for reference.

Thanks,

ADrian Hauser

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Adrian Hauser
Film Handler

Posts: 44
From: Sydney
Registered: Mar 2008


 - posted 09-16-2011 08:06 AM      Profile for Adrian Hauser   Author's Homepage   Email Adrian Hauser   Send New Private Message       Edit/Delete Post 
We have reordered a Matte Preview screen as a replacement.
It seems the problem was a manufacturing issue possibly from the calendering process.

Regards ,
Adrian

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