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Author
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Topic: Barco R6 Performer Convergence Drift
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Frank Angel
Film God
Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999
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posted 08-11-2010 08:00 PM
The park venue this summer forewent the use of our usual 35mm film and opted to go with video only, using our spanking new (well, three yr old) dual Barco R6 Performers 3 chip DLP projectors in stacked configuration. I was not at the site this year so I gave a call to find out how the Barcos worked out.
He gave a litany of problems, mostly with the source material-- artsy fartsy crap that had been taken from DVDs and "authored" by the musicians who were commissioned to write and perform a score to the film (eveyone thinks they are video editing experts). These guys evidently screwed up the aspect ratio -- they tried to make an anamorphic source fit into 16:9 and had actors' faces and heads sliced off by the edge of the frame; then they complained it was the projector.
But aside from that, there was a serious issue with the Barcos not being able to holding their convergence. Because it is an outdoor venue, naturally they have to align the two projectors the night before, getting the two grids to fall perfectly on top of each other. After that painstaking task, the crew would go home for the night.
Come the next day, the day of the show, the audience arrives around 6pm, sun sets, projectors are fired up, they hit the screen and the images are off by 5 and 6 inches, and in both axes. They couldn't do anything but to just kill one of the projectors. This happened EVERY night.
A call to Barco revealed that in stacked operation, the projectors CAN'T maintain convergence. They were told that heat, lens age(?) and warm up and cool down will combine to make convergence unstable. (Yah, the Barco tech said as the lens age, they change -- this sounds like gobbledygook to me, but that's what the PD said he was told.
Anyway, has anyone ever heard of this problem? Is this a problem with all projectors when they are used for dual operation, or particular to this Barco model? If this is true, then why bother selling a $400 stack lock-down frame? If you have to align the units every time you fire them up, you might as well just sit them on a table.
Bottom line -- this makes these units pretty useless for stacked operation at this venue because there is no way they can ever be aligned prior to the audience arriving. The audience must be let into the park when the sun is still out, and of course you can't see a damn thing if the sun hasn't set....and I mean SET. So unless they want to wait until it gets dark and do the alignment process with a stagehand at the screen with a talkie-walkie, painstakingly relaying information back to the booth with the audience sitting there watching, you are pretty much screwed.
I am thinking the only way around this would be for them to align the projectors very early in the am -- 3am or 4am and just leave the projectors running all day long -- not terribly practical, burning the lamps for 16 hours for a 2 hour show and calling in a crew to pull in the screen for the alignment, then pull it up again; at least a 5 man crew/4 hour call.
They asked me for my advice on what to do. You all know what I told them, right?
RUN FILM DAMNIT! That's what we have two Century SAWs for. And they'll freakin stay aligned all summer long too!
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Frank Angel
Film God
Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999
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posted 08-13-2010 05:29 PM
Hey guys -- no, it's the alignment of between the images of the two projectors, not the convergence of the DLP chips within that goes wacky. And yes, they DO power them down at night by actually killing the AC power at the distribution panel, so the projectors are not getting any "stay alive" voltage. Whether or not this is the culprit, it will be easy to determine.
Then there is the possibility that the units need to have the bulbs shut down but the circutry kept in the standby mode. That can be easily checked as well. But other than that, I can't see why physically anything should change so drastically. The lenses are moved mechanically (as far as I know) so once they are shifted to the correct position, there is no reason why they should change. Same with the zoom.
The projectors themselves are mounted in Barco's locking frame so in theory, you should be able to move them around in it and it will keep them aligned.
I am agreeing with you guys though, for them to go so far out after being aligned perfectly, there has to be some parameter or more what could possibly revert to a default if the AC mains are disconnected. We shall see.
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Frank Angel
Film God
Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999
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posted 08-15-2010 11:12 AM
Mark, my understanding is that they DID leave the power on and the problem remained. They called Barco and were told it could be an "aging" problem, which sounds to me like our guy who spoke to the Barco tech didn't understand him (highly unlikely as he is a top draw lighting designer/technician and now production manager and he can certainly understand most things technical), or the Barco rep didn't understand -- yes, lenses can drift because of heat, but when we do the alignment, they stay converged throught a 2 hour run thur, so that would be pretty much ruled out. I would think it is more likely something to do with the motors returning (or not) to the memorized postion.
And I agree, for this to be happening, that two relatively expensive projectors which in theory are designed for stacked operation, can't hold alignment is unacceptable.
I highly doubt that it's any of the physical support structure because if anything moved there, both projectors would move together -- they are mechanically locked firmly to the Barco stack rig. If the lenses were an issue due to weight, then one would expect to see vertical displacement, which is not the case. The one time I saw this misalignment it was on the horizontal plane -- I can't be sure if there wasn't any vertical displacement as well since as soon as the image hit the screen, the problem was immediately apparant and one of the projectors was killed. It seemed to me it was definately horizontal error.
Problem with tweeking before the show -- before the show is daylight. The audience is let into the park around 6pm -- WAY to light for you to see anything on the screen. At 7:30pm there is a first live act, by the time that is over, it is still barely dark enough to see a decent picture. The screen has to be dropped by motorized truss, set in place, anchored and around 8:45pm it is dark enough to play the movie. So the audience has been in their seats for over an hour. The only way to tweek the convergence would be to do it in front of them. And the tweeking isn't simple -- it involves a stagehand at the screen with a walkie-talkie talking the projectionist thru because you need to be right up to the screen if you expect to get near perfect pixal-to-pixal overlap, and it's time comsuming. For an audience to have to sit thru that is unacceptable.
The venue had it's last show this weekend so this problem will have to be resolved next year.
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