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Author Topic: Yellow splotches on the screen? Mark J. Marshall Film God Posts: 3188 From: New Castle, DE, USA Registered: Aug 2002 posted 11-18-2011 09:14 PM                    I'm sitting in a DLP equipped theater right now. Not sure what projectors they're using. There are splotches of yellowish color across the bottom of the screen. They are not on the surface of the screen. They're being projected. What could cause that?  |  IP: Logged James Westbrook Phenomenal Film Handler Posts: 1133 From: Lubbock, Texas, Usa Registered: Mar 2006 posted 11-18-2011 09:20 PM                     Do the splotches look like pixels?  |  IP: Logged Mark J. Marshall Film God Posts: 3188 From: New Castle, DE, USA Registered: Aug 2002 posted 11-18-2011 11:29 PM                    Nope. Big yellowish smears across the screen. Image on porthole is over under... Implying Sony projector.  |  IP: Logged Paul Mayer Oh get out of it Melvin, before it pulls you under! Posts: 3836 From: Albuquerque, NM Registered: Feb 2000 posted 11-19-2011 12:37 AM                        Not necessarily. RealD's XLS double-barreled lens is indeed for Sony's, but RealD also makes the XL and XLW units that will fit onto NEC's (and I assume other projectors) - they too produce a over-under double image on the port glass, with the top image being larger than the bottom one on the glass. As for yellow at the bottom of the image, not sure. Sounds like the bottom of the blue imager is being masked or cropped by something...  |  IP: Logged Robert Grandrath Film Handler Posts: 5 From: san jose ca usa Registered: Aug 2011 posted 11-19-2011 12:40 AM                     Perhaps a misalignment of the integrator rod? I had this happen with a BARCO series one. The yellow is just the edge of the "shadow" caused by the misalignment.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 11-19-2011 12:50 PM                     I don't know Sony, but as Robert said, I saw this yellowish border when the intergrator rod or the cold mirror were not aligned on a Barco. They were not splotches though.  |  IP: Logged Mark J. Marshall Film God Posts: 3188 From: New Castle, DE, USA Registered: Aug 2002 posted 11-19-2011 03:43 PM                    Ok, I grabbed some images from my phone. This is not the first time I've seen this phenomenon. The snipe at the beginning claimed that we were watching Sony 4K. The images on the porthole were the same size. This was a Regal theater if that helps. Anyway, first the blank screen. They had the work lights on while they were seating in this theater due to the size of the crowd. No splotches on the screen. Next, here's a shot from the Sprint ad. Some of the yellow splotches are circled. Here's another ad with arrows pointing to the same spots. Note the huge arch on the left. And a few lines and spots on the right and across the middle. There were a few others higher up in the middle of the image too, but they were hard to see on with my camera phone. Finally one more ad: I've seen a damaged reflector on a 35mm projector show yellowish spots on the screen like that, but the damage was the result of a bulb explosion and the discoloration was very easy to see. This was a bit more subtle. Any thoughts?  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 11-19-2011 10:32 PM                     wonder if these are fingerprints on the polarizers breaking up the light spectrum since I heard that the polarizers can now be swung out of the way for 2D showings and returned to their stops for 3D showing... Was it like this also during the feature, or just during their "first look" video presentations?  |  IP: Logged Paul Mayer Oh get out of it Melvin, before it pulls you under! Posts: 3836 From: Albuquerque, NM Registered: Feb 2000 posted 11-19-2011 10:36 PM                        Given that they ran the 4K Sony CineAlta snipe, and this was at a Regal, and the images on the port glass were the same size, yes it was a Sony using the RealD XLS double-lens. As for the splotches, eww! I've only read about this and not seen it with my own eyes, but that looks like the description of a blue SXRD imager or optics that has been over-heated or cracked. Or it could be that the blue optics are just very dirty. Or any combination of these things.  |  IP: Logged Mark J. Marshall Film God Posts: 3188 From: New Castle, DE, USA Registered: Aug 2002 posted 11-20-2011 06:46 AM                    Thanks for the info, guys. I've not worked on these before, nor do I know much about them. But is there any reason why the blue imager would be more prone to those things than any other color? I've seen it in a couple of auditoriums in this area. I'd like to be able to tell the managers what the problem is since they would likely not have a clue where to start looking. Sorry the images from my phone were so crappy. They really don't show off the problem all that well. You can see it in the pictures, but trust me the yellow is ugly as hell seeing it in person. It's not a slight yellow tint like in the pictures I posted. It's not a bright solid yellow either in the way that a stuck pixel is a bright solid color that never changes. But it is a "really-hard-to-miss" yellow tint. Anything black and white really shows it off. If you've been a projectionist trained to look for problems your whole life your eyes will be drawn right to it.  |  IP: Logged Dominic Espinosa Phenomenal Film Handler Posts: 1172 From: Boulder Creek, CA. Registered: Jan 2004 posted 11-20-2011 11:20 AM                     Paul hit it on the head. The blue imagery in the prd. Sony says that spectrum is stronger. My guess is proximity to the light source. Its the coating on the prism that gets toasty. Although there could be fingerprints on it accelerating its decay. Usually it presents as an even area, not splotches.  |  IP: Logged Mark J. Marshall Film God Posts: 3188 From: New Castle, DE, USA Registered: Aug 2002 posted 11-22-2011 02:52 PM                    So would damage / dirt on a different color imager produce different colored artifacts on the screen?  |  IP: Logged Paul Mayer Oh get out of it Melvin, before it pulls you under! Posts: 3836 From: Albuquerque, NM Registered: Feb 2000 posted 11-22-2011 04:44 PM                        Using additive (not subtractive) color mixing as in the prism optics of a digital projector - R+G = Yellow G+B = Cyan B+R = Magenta So, a blue channel blockage will yield a yellow image, a red channel blockage will yield a cyan image, and a green channel blockage will yield a magenta image.  |  IP: Logged Ron Funderburg Jedi Master Film Handler Posts: 814 From: Chickasha, Oklahoma, USA Registered: Nov 2007 posted 11-22-2011 04:59 PM                        Paul if a specific color on the prism has damage or is being fed improperly wouldn't the color problem be picture wide? That is to say all over.  |  IP: Logged Mark J. Marshall Film God Posts: 3188 From: New Castle, DE, USA Registered: Aug 2002 posted 11-22-2011 06:34 PM                    Great, Paul. Makes perfect sense. Now the only question I have left is why do I keep seeing yellow? Why is it the blue imager that is always the problem around here? Does it get the hottest for some reason? Is it the one that's easiest to touch by accident? Or is it all just a coincidence?  |  IP: Logged

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