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This topic comprises 2 pages: 1 2
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Author
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Topic: NEC 2000C Moire Pattern - Possible Causes?
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Jim Cassedy
Phenomenal Film Handler
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Posts: 1661
From: San Francisco, CA
Registered: Dec 2006
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posted 01-04-2015 04:22 PM
I'm doing a preview later tonight at one of the screening rooms where I sometimes work. "The other guy" just informed me that the bulb on their NEC 2000C projector was recently changed, by a professional service tech and that ever since then, hs's noticed a slight moire pattern on screen that he's never seen before. (And I've worked there many times and if the moire was there previously, I know I would have seen it.)
The otherprojectionguy sez that nothing else was changed or adjusted (other than the normal bulb-change-alignment) when the new bulb went in.
I said I'd go down early & takalook, but quite frankly, I'm not sure exactly what I'm looking for. Does anybody have any ideas?
It's an NEC 2000C- - and I beleive they have a 2K bulb inside, since it's only a screening room with a screen around 12-15ft wide, if I recall.
He sez he's seen it on both flat and scope. The projectorthingy is equipped with Dolby 3D, which hasn't been used since the bulb change. (and the wheel should be well outta the light path & probably OK)
I'm heading down there shortly, so if anybody has any ideas, please chime in!
THANKS! -Jim C-
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Jim Cassedy
Phenomenal Film Handler
![](http://www.film-tech.com/ubbmembers/4115a.jpg)
Posts: 1661
From: San Francisco, CA
Registered: Dec 2006
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posted 01-05-2015 12:33 AM
So, Mark- There's never been a moire pattern at this location before.
I did notice that the projector has been moved very slightly from its' previous position, and that might have been enough to cause the moire to appear, from what you are telling me.
I didn't see your message till I got home, but in the course of checking things, I did move the lens focus & zoom slightly and that seemed to clear up 98% of the moire. When I first got there, you could see it all over the screen, especially if you put up a peak or 50% white field.
After 'fiddling' with the lens settings a bit the moire is now confined to one small spot in the lower left hand corner on a 'white screen' and it's totally invisible during actual content.
I'll go back later this week when I have time & play with the projector position & check the level, but my time was limited today.
As I mentioned to you once before, I still really want to go to the "NEC Projector School" for some advanced operator training or something like that.
Barco & Christie Tech's are a dime-a-dozen here in SF, but NEC techs, not so much so. And I regularly deal with over half-a-dozen NEC's, so it would be worth my time.
I don't care what the school costs- - that's not a problem. I'm still trying to find a hole in my schedule big enough for me to attend, and I'm still unsure exactly how to get into one.
Thanks for the moire advice
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Jim Cassedy
Phenomenal Film Handler
![](http://www.film-tech.com/ubbmembers/4115a.jpg)
Posts: 1661
From: San Francisco, CA
Registered: Dec 2006
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posted 01-05-2015 10:39 AM
quote: Carsten Kurz It may be that the moire has not been noticed before.
Oh ho ho ho! Not very likely. Not only would I have noticed it on one of the many occasions I've worked that room, but one day last summer I spent 18hrs in that room working with a group of optical engineers who were contracted by a consortium of several of the large theater chains to evaluate different types of 3D glasses provided by several manufacturers.
The day before the test a complete alignment& re-bulbing of the projector was done. On the day of the test they hauled in two huge road cases of scientific equipment, and spent the first several hours just calibrating everything. They also had two of those incredibly expensive (around $12,000 us)screen meter-things that they used to establish 'basline' data for their tests, and also to take readings every two hours to certify that the light levels were not 'drifting' any during the course of the day which would have affected their test results if they didn't factor those corrections (if any) into the data they were collecting.
95% of the work they were doing involved 'shooting white light' on the screen.
Believe me- - if there had been a moire or ANYTHING wrong with the system that day, they would have stopped everything.
I had to sign a non-disclosure agreement, so I couldn't take any pictures and exactly what they were doing and who they were specifically doing it for is still proprietary information. It will eventually be released in some form, and they promised they'd let me know when that happens. A professional photographer took a sh_tload of photos of the set up that day, as part documenting the way they collected the data.
I hope I can share those once the info is published.
(It was a long, but easy day for me. - I got paid a wholebuncha money to basically just stay out of their way all day. Nice!)
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