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Author Topic: Barco light sensor Jay Glaus Expert Film Handler Posts: 123 From: Pittsburgh, PA USA Registered: Dec 2010 posted 04-26-2015 06:07 PM                        I was touching up the alignment on my 32B today, and noticed something strange. I was watching the alignment chart on communicator, and as the bulb is on, it will be reading 10.50 Ft/L, and without really touching anything will plummet to 8.00 within a second. Then, eventually, it will come back up. I know sometimes the arc can wander and you can have a slight flicker, but I would have to believe a sudden drop of slightly over 2 Ft/L would be noticeable to the eye. The other thing I thought was strange, was a few times it plummeted, no matter what adjustment you made, it really didn't change it until it decided to come back up. I honestly do not believe the brightness is changing as much as it is the number on the sensor. The bulb is fairly new, and i cannot really see any flicker. I ended up aligning the bulb off my eye, because the number on communicator began to bounce so rapidly, it basically became useless. I tried closing and reopening communicator too, and rebooted the machine once. I'm sure the alignment isn't great, but it will get me through the night. I don't have a light meter, but I know somebody who does. He's going to bring it out in a day, and we are going to try to align the bulb using an external light meter. I even tried making a new calibration file for the light sensor, on the assumption that i was getting 10 ft/l on the screen. Even though the calibration file would be incorrect, I wanted to see if it would still bounce with a new file, and it did. I believe the light sensor in that 32 is going. Does anyone else agree? Thanks, Jay  |  IP: Logged Tim Sherman Expert Film Handler Posts: 125 From: North Ridgeville, OH, USA Registered: Aug 2000 posted 04-26-2015 06:36 PM                        Before you blame the CLO sensor, First make sure you are not in CLO mode when doing a lamp alignment. It should be in normal mode Second did anyone ever check the orientation of the magnet in the lamp house. There is a info-t on the 32B, some of them had magnets reversed when they were manufactured and that can cause an unstable arc.  |  IP: Logged Jay Glaus Expert Film Handler Posts: 123 From: Pittsburgh, PA USA Registered: Dec 2010 posted 04-26-2015 07:07 PM                        Hi Tim, No, I'm not in CLO. In fact, I actually don't use CLO. maybe i'm old school from the days of film but I like to know right about where the bulb is ,and be the one to take it up if needed. That way I know if I have one darkening bad. As for the magnet… Yes, ours was in backwards. We changed it shortly after the info-t came out a while back.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 04-27-2015 01:15 AM                     Which version are you using? I've seen this with 1.13,but it may have been a lamp/ballast/sensor issue, it was the only machine I've seen with 1.13 so I can't be sure it was a software issue.  |  IP: Logged Jay Glaus Expert Film Handler Posts: 123 From: Pittsburgh, PA USA Registered: Dec 2010 posted 04-27-2015 02:10 AM                        Honestly I believe my 32 is still running 1.12, I need to update it. But I'll double check when I'm out there tomorrow. My communicator is 4.9.14. My alignment by eye was better than I thought it would be. I'll be interested to hit it with the light meter Tuesday. I did go around the front of the booth during projection, and stared straight down the lens to see how well I centered the bulb, and it looked pretty good for now. I have a new problem though. Theres a big pesky black spot on the front of my laptop screen that won't seem to go away no matter what I clean it with  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 04-28-2015 05:24 PM                     Here is a topic from last year on the 32B stabilizing magnet issue. Barco 32B Magnet I had 4, 32B units with reversed magnets installed in the module. Bought a compass to check polarity and to help correct the polarity. -Monte  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 04-28-2015 10:54 PM                     Beware of Barco 8/10 projectors, the CLO sensor is nutty. Light level reported depends on what's projected: black reads lowest and white reads highest. I haven't figured out why or how this happens. The lamp power will vary with scene brightness changes if it's run in CLO mode, I think maybe recent software locks out power changes some time after a macro is executed though.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 04-29-2015 01:06 AM                     Wow, really! Thanks for the heads up.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 04-29-2015 06:52 AM                     I wonder if they are trying some primitive form of contrast ratio improvement. That said, it is normal for CLO to be locked out 5 minutes after a macro change (historically...I haven't verified this on an S series).  |  IP: Logged Pete Naples Phenomenal Film Handler Posts: 1565 From: Dunfermline, Scotland Registered: Feb 2001 posted 04-29-2015 08:01 AM                     I wonder if the CLO sensor is located after the DMDs? I too have observed this behaviour. On a B or C you can happily line up the lamp with content playing, try it that way on a 8 or 10 and see how far you get!  |  IP: Logged Tim Sherman Expert Film Handler Posts: 125 From: North Ridgeville, OH, USA Registered: Aug 2000 posted 04-29-2015 10:38 AM                        Clo sensor is attached to the folding mirror before the Prism and the DMDs  |  IP: Logged Pete Naples Phenomenal Film Handler Posts: 1565 From: Dunfermline, Scotland Registered: Feb 2001 posted 04-30-2015 04:07 PM                     That's true for B & C but is it for S? I don't follow why the CLO reading jumps all over the place with content.  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 04-30-2015 04:53 PM                     Probably some light-spill or back-reflection. Just why didn't they catch this issue in time? Having a functioning light sensor/CLO is not the most exotic feature. - Carsten  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 05-01-2015 03:17 PM                     It's a shame, the light calibration has always been very accurate on a Barco. Something Christie don't have. If I service a projector with an old lamp and I calibrate the light, if the light level is - say - 12fL, on a Barco I can dial 14fL on the macro: when the lamp gets changed the CLO will adjust to reach 14fL. Same the other way round, when I find that the lamp installed is too powerful and I recommend for a smaller one: the projector will adjust to the correct level when that is done (within a reasonable accuracy). This cannot be done on a Christie.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 05-02-2015 01:57 AM                     That is not entirely correct. Christie uses a "target number". It is just not referenced to any particular fL reading. When I install a Christie projector, I set up any desired light loc calibrations I may need and name them appropriately. That is, if I want a 14fL Flat and a 14fL scope...I'll manually set the light to 14fL and then label the setting something like FLAT14fL and set the lightloc to that number. Likewise for the Scope format (and on down the line for any/all lens zoom or anamorphic settings). So while the Christie will not read out in fL (you can "calibrate" its sensor for ONE format, that is indeed inaccurate) you can set up as many suitable lightloc calibrations that are as accurate as your light meter. The projector will keep the lamp at that level to the best of its ability (and potentially to the lamp's detriment if allowed to go over 100%) For sure though, Barco has everyone beat on the lamp calibration thing and they let you have it read out in fL with reasonable accuracy (not taking into account the optical items after the sensor...i.e. screen, port glass). THE most worthless sensor is NEC's. It too is just a number but it has no basis on anything, including brightness. Setting for the highest number often doesn't mean the brightest or most even picture. That said, NEC will, like Christie allow you to "mark" your desired setting, save it, recall it and use "Feedback" to account for lamp aging. From what I can tell in my limited tests, it seems to lock onto your settings pretty well. What Christie really beats the others on is lamp alignment. What a pleasure that thing is...it gets you 95-100% there and it does it pretty darn fast on the series 2 projectors. Barco's automatic lamp adjustments (if you buy the rather expensive upgrade) is horrendously slow (15 minutes or so) and is hit/miss at best on the alignment and seemingly never gets it 100%. That said, Barco is the clear winner on manual alignment...the lamp adjustments combined with the "green dots" makes it rather quick and accurate. NEC is the clear loser there with the most sloppy lamp adjustment that seemed to copy Christie's old "H" series lamp adjustments...with all of their failings.  |  IP: Logged

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