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Author Topic: Aperature problems? Mike Lauber Film Handler Posts: 19 From: Fond du Lac, WI, USA Registered: Nov 2002 posted 02-09-2003 01:50 PM                     Hello there. A couple of the screens at my theatre are beginning to have problems where the picture doesn't fill the entire screen or spills over onto the curtains. Some fill it perfectly vertically, but don't fill it horizontally. Some don't fill it properly vertically. Also, on some screens it will fill the screen just fine with a scope lens/aperature, but not with flat, or vice versa. The curtains stop in a fixed location in each theatre for flat and scope films, so I doubt they are the problem. These problems are too small for most people to notice presently, but I would like to correct the problems before they get worse. How can I fix these problems? Mike  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 02-09-2003 02:20 PM                     If the apertures were cut properly from day one, there are other factors that need to be looked at such as is the floor sagging, is the projector moving about the projection booth, is your masking rigging set properly, is your lamp properly aligned, and is the lens holders in the projectors worn out allowing the lens to flop around? These are just a few, but not all, things to look at. Edit...Tim, does that look better? Making new apertures will not solve your problem until you find out "what is changing" in your enviroment. [ 02-09-2003, 07:19 PM: Message edited by: Paul G. Thompson ]  |  IP: Logged Tim Reed Better Projection Pays Posts: 5246 From: Northampton, PA Registered: Sep 1999 posted 02-09-2003 03:24 PM                       Hi, Mike! Paul is right, you should look to find out what has changed. Make sure no one has swapped aperture plates from one house to another - that's fairly common. Also, make sure the same lenses are being used in the same projectors everytime. And, if you have turrets, the adjustments on them can slip and cause the lens to shift from the ideal position. Any of these conditions can cause over spill or aperture edges to show on the screen. Since we were just talking about spelling on another post, and as a point in fact, please note they're apertures, not aperatures. Paul, you should know better - start banging those erasers. Mr. Reed, 3rd period English teacher  |  IP: Logged Mike Lauber Film Handler Posts: 19 From: Fond du Lac, WI, USA Registered: Nov 2002 posted 02-09-2003 05:12 PM                     I don't believe it's the projectors moving, because on most of them, the picture is still fine vertically, and too narrow on BOTH sides of the screen, so it couldn't have just shifted one way or the other. What exactly is the masking on the projectors? How do I adjust it? Is it possible for the aperture plate to become slightly warped? I've been thinking of simply filing down the aperture plates. Mike  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 02-09-2003 05:27 PM                     Mike, when you go from flat to scope, does the side curtains open, or does the top masking come down from the ceiling? Do you have masking motors, or do you go down into the auditorium and pull a rope on a pulley? I have seen rope stretch as well as the set stop points on masking motors drift. Still, *most* of the time it is turret related. It would also help to know what kind of projectors you are running, and if you have turrets or if you swap the lenses out to change formats.  |  IP: Logged Mike Lauber Film Handler Posts: 19 From: Fond du Lac, WI, USA Registered: Nov 2002 posted 02-09-2003 05:42 PM                     We pull curtains on the sides. Rope streching is one strong possibility I suppose. We do not have turrets on any of our projectors. I change the lenses manually. I'm about to go to work right now, so I'll check exactly which projectors are having problems and post again later. Thanks. Mike  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 02-09-2003 06:28 PM                        I'm betting that someone accidentally swapped aperture plates between projectors or is doing something like using Academy plates for scope prints. (scope plates are taller than Academy plates) Is this theatre a newly constructed house (built in the last few years) or an older theatre? With new installations, it seems fairly common for the building and masking to "settle" over the first few years and that may be part of what you are seeing as well.  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 02-09-2003 06:49 PM                     Tim, I blame the keyboard. So, "Pbpthbpthbthp!" Tim, I tried to use "white-out" on the monitor...but that didn't work....  |  IP: Logged Tim Reed Better Projection Pays Posts: 5246 From: Northampton, PA Registered: Sep 1999 posted 02-09-2003 09:22 PM                       Ummm-hum. When all else fails... blame the equipment!  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 02-09-2003 10:24 PM                     Well, it works when you blame the dog...  |  IP: Logged Rick Long Jedi Master Film Handler Posts: 759 From: Toronto, Ontario, Canada Registered: Nov 1999 posted 02-09-2003 10:42 PM                     "The curtains stop in a fixed location in each theatre for flat and scope films, so I doubt they are the problem." How do you know they are still stopping at the same place as when the apertures were first filed? Ropes can strech, and limit switches can drift due to mechanical wear. They worked well once. Last thing I would touch is an aperture file and NEVER without RP-40.  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 02-10-2003 01:41 AM                     Jeeze, Rick. I thought I read WD-40 instead RP-40. I guess I fit the typical projectionist...Blind in one eye and can't see out the other..  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 02-10-2003 09:08 AM                        You can order test films directly from the SMPTE. Theatre equipment dealers often carry them in stock too, and may sell short lengths of 35-PA for loops to verify projected image area (Never use a loop of 35-PA for anything else, like evaluation of resolution or steadiness --- only a full length in good condition should be used for that.) http://www.smpte.org/smpte_store/test_materials/ I agree the most likely cause was that someone switched plates among theatres, or the screen masking stops got out of adjustment. If the theatres were set up properly in the first place, there should be NO need to file apertures.  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 02-10-2003 02:21 PM                     John said: quote: I agree the most likely cause was that someone switched plates among theatres, or the screen masking stops got out of adjustment. If the theatres were set up properly in the first place, there should be NO need to file apertures. This happened to me last night. The aperature plate was in upside down. The reason was it was not cut for that particular house. I found the orginal aperature, put it in, and problem solved. To eliminate the "switcharoo" situation, I just put all the aperature plates that were adrift in the booth in my pocket. Right now, they are sitting on my desk.  |  IP: Logged Andrew Duggan Expert Film Handler Posts: 127 From: Albany, NY, USA Registered: Jun 2002 posted 02-10-2003 02:40 PM                        Mike, if the problem does turn out to just be that the apertures were cut for different houses, once you have them sorted out, get yourself a pointed diamond file, or something similar, and *lightly* etch the correct theater number (and correct aspect, if it's not already printed on there) onto the plate. Just be sure not to damage or bend it!  |  IP: Logged

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