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Author Topic: Barco 23B picture shaking after lens replacement Michal Matys Film Handler Posts: 70 From: Prague, Czech Republic Registered: Nov 2014 posted 03-26-2018 09:34 AM                    Hi all, I have recently swapped lens in two Barco 23B projectors. The lens I was using before, was 1.2" 1.45-2.05. New ones are 1.2" 1.25-1.83. New lens is much "longer and bigger" than the previous one, I do not know how this could be related, but after the lens replacement, there is a visible shaking of the picture when displaying test pattern. I have swapped pump with other projector, most of the fans, turned off the exhaust fans with no help. I have also checked the lens holder, the lock nuts for scheimpflung adjustment are tightened, everything seems in order. My question is, did any of you ever experience this? What was usually cause of picture shaking in your Barco projectors? Maybe this is coincidence, but since it is related to two projectors where the same lens was installed, it is strange. Dont know how the lens could affect this tho. Thank you Michal  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 03-26-2018 10:28 AM                     Yes, this is common with Barco B machines. It is the way the lens mount is designed. Make sure your Scheimpflug (I love this word!) is fully tightened - but make sure you know what you are doing if you play around it!! B's lens mount feature an antivibration spring/bearing at the top. Make sure the bearing actually touches the mount and the spring is set for maximum pressure. You will need a headtorch to confirm whether the bearing fully touches the metal. Also try decoupling the extract fan from the chassis - just hold it a few mm away from the chassis with your hands should work but make sure you do it safely, wearing safety equipment at all times. If nothing works, you may need the new "enhanced" stabilising device that replaces the basic bearing at the top of the lens mount. I've also seen a unit requiring a whole new lens mount as the lens was literally wobbling in its socket when fully fitted.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 03-27-2018 06:58 AM                     I've found that using the InVision lenses often will result in an image shake. Depending on the projection angle and outside stimuli (vibrations), you will see a substantial image movement. Barco sells a lens stabilization kit that will substantially address the problem. Why they have not incorporated it into production still escapes me. The current system, as described above merely puts downward pressure on the lens mount but still allows unrestricted lateral vibration as well as pitch variations as the lens moves fore/aft. The improved upper mount applies a linear bearing like the ones on the bottom of the mount that effectively restricts the lens mount from vibrating laterally or pitching. It can only move in/out for focus, as it should.  |  IP: Logged Alan Gouger Jedi Master Film Handler Posts: 501 From: Bradenton, FL, USA Registered: Jul 2000 posted 03-27-2018 10:42 AM                        "Moving Image Technology" offers a nice solution. http://www.movingimagetech.com/product/lens-stabilizer/  |  IP: Logged Jerry Axelsson Expert Film Handler Posts: 107 From: Stockholm, Sweden Registered: May 2005 posted 03-27-2018 11:16 AM                     Instability in the exahust fan of the Barco projector causing the longer lens to move more than the previous one?  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 03-27-2018 11:21 AM                     LOL! You never have this kind of issue wiith any of the NEC's, granted scheimpflug is a lot bigger pain to do on them. Mark  |  IP: Logged Sean McKinnon Phenomenal Film Handler Posts: 1712 From: Peabody Massachusetts Registered: Sep 2000 posted 03-27-2018 02:19 PM                        Your right Mark, you only have the issue where after the projector has warmed up for 20-30 minutes the entire focal plane changes and you have to refocus the image.  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 03-27-2018 02:40 PM                     I would highly question that MiT lens stabilizer. And what exactly happens when formats are changed and a lens rehome is performed? I'll bet damage happens to the lens mount. That is probably only useful for those "premium" ( ) screens with no masking that only have one lens setting and all lens files are removed from all macros.  |  IP: Logged Sean McKinnon Phenomenal Film Handler Posts: 1712 From: Peabody Massachusetts Registered: Sep 2000 posted 03-27-2018 03:07 PM                        There is much debate on whether it causes artifacts or not but you can use resizing to move the image on the chips instead of moving the lens not that it makes the "lens stabilizer" a good idea.  |  IP: Logged Kirk Futrell Film Handler Posts: 95 From: Nashville, TN / U.S.A. Registered: Nov 2008 posted 03-27-2018 03:43 PM                        According to the MiT website : The lens is supported by non-marking nylon transfer balls that allow the lens to continue to rotate and move in and out for focusing and zooming. If installed properly it seems like it shouldn't cause a problem.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 03-27-2018 09:30 PM                     quote: Sean McKinnon Your right Mark, you only have the issue where after the projector has warmed up for 20-30 minutes the entire focal plane changes and you have to refocus the image. Then you're definately doing something wrong! 334 NEC's installed and no issues like that at all. Many S2 NEC are now 7+ years old. The Invision lenses do not work in them! They only work correctly in the 3200 and 3240. Mark  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 03-28-2018 07:33 AM                     Don't forget about the 20% of your light you flush away when using an NEC or the complete lack of lens accuracy with the NEC (repeatability). Then again, Mark, I fail to see when one is seeking help with a product of brand A, you feel the need to bring up brand B. It isn't a solution or help, it is just dickish. Suffice to say, whatever brand product one has or likes, there are the good points and the bad points. What is dumb about the "B" series Barcos is that THEY HAVE THEIR OWN SOLUTION but fail to use it.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 03-28-2018 09:17 AM                     I disagree Steve and the fixes offered for the Barco are childish at best. Where is the manufacturer and why havent they stepped up to address the issue properly themselves? Mark  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 03-28-2018 10:23 AM                     What do you disagree with? Little of what I said is matter of opinion. I agree that Barco should have addressed this issue, especially since they have a proper solution.  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 03-28-2018 01:36 PM                     quote: Kirk Futrell According to the MiT website : The lens is supported by non-marking nylon transfer balls that allow the lens to continue to rotate and move in and out for focusing and zooming. If installed properly it seems like it shouldn't cause a problem. Again, what happens when the lens is rehomed??? Every manufacturer's lens design needs their version of rehoming every once in awhile. Image shift on the DMDs won't stop that.  |  IP: Logged

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