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Author Topic: Scope going off bottom of screen John Hawkinson Film God Posts: 2273 From: Cambridge, MA, USA Registered: Feb 2002 posted 12-08-2003 09:34 PM                     You want a sledge hammer because you want to lightly tap the pedestal base in small steps. If you use a crowbar or a screwdriver, you're prying, which isn't desirable here. You just want to inch it over. --jhawk  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 12-08-2003 10:12 PM                     Antonio: There is no "zero point" for framing my projectors -- actually, there is (kind-of) but it is not marked. To find the zero point, I ran some RP-40 with the pinhole aperture plate in position and used the hole in the plate as the target for the diamond on the test film. It is important to align the centre of the lens to the centre of the gate/aperture and not just the film. -- Manny.  |  IP: Logged Richard Greco Phenomenal Film Handler Posts: 1180 From: Plant City, FL Registered: Nov 2003 posted 12-08-2003 11:39 PM                     The thing is, if I adjust the projector vertically, then the picture will be on the top curtain off screen. I am getting Stuck on You in that theatre Thursday, I'll see how that fares out. Could it be maybe the movie in the auditorium? I have Haunted Mansion in there right now.  |  IP: Logged Darryl Spicer Film God Posts: 3250 From: Lexington, KY, USA Registered: Dec 2000 posted 12-08-2003 11:50 PM                    What does your other screens look like. Do they have problems with the Scope image. It could be possable that the plate is the wrong one for that house.  |  IP: Logged Richard Greco Phenomenal Film Handler Posts: 1180 From: Plant City, FL Registered: Nov 2003 posted 12-08-2003 11:52 PM                     Darryl, all of the other screens (aside from the 3rd, which only does flat) play scope fairly well. I did notice that this screen seemed to be curved more on the left than the right.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 12-09-2003 12:11 AM                     Pinhole plates often are punched uncentred I use the 35PA and adjust the framer to produce an equal location setting at the extreme edges of the projected trap  |  IP: Logged Antonio Marcheselli Phenomenal Film Handler Posts: 1260 From: Florence, Italy Registered: Mar 2000 posted 12-09-2003 03:22 AM                        Manny I agree, but then you said that you align the (aligned) projector using the scope image without aperture plate... How can be sure that the frame setting is correct? You said that you set the frame using the pinhole aperture plate, ok (if the hole is in the center). Gordon, If Pinhole aperture plate has not always the pin in the center of the plate, how can a aperture plate be made? Since I adjust the plate basing on RP40, how can be sure that RP40 is in perfect frame? I still don't know if I'm clear! ask if necessary!! Bye A  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 12-09-2003 08:46 AM                     Gordon: Ordinarily, I would defer to your deeper level of experience with a variety of equipment. I am sure that you have seen many a funky-looking pinhole plate so I'm not going to disagree on that point. In my case, however, these pinhole plates look just fine to me. Sure, they *could* be off-centre by a millimeter or so -- I never measured -- but I'm not really interested in splitting hairs over that. I'm using the same pinhole plate for each projector and I think that gives me a better shot at consistency than just "eyeballing it." -- Manny.  |  IP: Logged Randy Stankey Film God Posts: 6539 From: Erie, Pennsylvania Registered: Jun 99 posted 12-09-2003 10:14 AM                     quote: Antonio Marcheselli: How can be sure that the frame setting is correct? I don't know how others think about this but, for the problem at hand, I don't think exact centering of the frame is called for. I think that all Richard needs to do is get the picture back on the screen then log the problem so that the tech. can look at it later. (Political factors aside.) Therefore, in this case, it would be sufficient to pull the aperture plate to see whether the image is generally where it's supposed to be. From that point, minor, temporary adjustments can be made to keep the show on the screen. (Literally! ) Dialing the projector up or down is something that can easily be "undone". If the projector is bumped laterally, there should be no problem bumping it back if it must. I don't think most techs would get bent out of shape for things like that. They probably WOULD if other adjustments were made without his/her permission! What's got me concerned is that Richard gives me the impression that somebody in management has "cheaped out" and has bought only one lens for some of the projectors. Do you have two lenses and two aperture plates for each projector? Don't worry about whether the masking moves on the screen. (Either manual or motorized.) Some companies "cheap out" and make a "One size fits all" screen. It's not the best thing to do but, if this is what has been done, you'll have to live with it. What I think is happening is that somebody has come along and switched lenses and aperture plates between projectors. I think there may have been some lenses damaged (lost?), which is why some houses only seem to play one format. Before going around and moving/adjusting any projectors, what *I* would do is make an inventory of lenses & aperture plates for each projector. If there is any clue that plates and lenses have been swapped around I would ensure that they are all back in the places they are supposed to be before going any further.  |  IP: Logged Antonio Marcheselli Phenomenal Film Handler Posts: 1260 From: Florence, Italy Registered: Mar 2000 posted 12-09-2003 12:11 PM                        Randy, Yes, I was Off topic, my questions were about centering the projector! Bye A  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 12-09-2003 12:38 PM                     Antonio said "Gordon, If Pinhole aperture plate has not always the pin in the center of the plate, how can a aperture plate be made? Since I adjust the plate basing on RP40, how can be sure that RP40 is in perfect frame? I still don't know if I'm clear! ask if necessary" The 35PA is shot in a pin registered camera and it is the reference to the recomended practice 40 All one has to do is open the pin hole up with a dremel tool and file to the correct dimensions for the format desired I have seen punched out plates all over the map for location  |  IP: Logged Daryl C. W. O'Shea Film God Posts: 3977 From: Midland Ontario Canada (where Panavision & IMAX lenses come from) Registered: Jun 2002 posted 12-09-2003 12:50 PM                        quote: how can be sure that RP40 is in perfect frame? Like Gord said above, which is the same thing I do, pull the aperture plate out, thread up the 35PA and frame it so that the same location lines are showing at the top and bottom of your projected picture. Of course your projected picture is probably going to be low and high on the wall or on the floor and ceiling since you've got no aperture in. That's fine... just frame it until the same location lines are projected at the top and bottom edges of the picture. Use your scope lens for this... you'll keep the picture on the wall and off the floor and ceiling. Once you've got the mechanism framed don't touch the framing for the rest of this. You can now align the projector to the screen and then cut and file your plates to fit the screen.  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 12-09-2003 01:01 PM                    quote: You want a sledge hammer because you want to lightly tap the pedestal base in small steps. If you use a crowbar or a screwdriver, you're prying, which isn't desirable here. You just want to inch it over. I make tiny corrections with my bases all the time (re separate discussion about lens mount misalignment) using a crow / pry bar. I have no problem making millimeter changes. This is with a conventional base (later Ballantyne) with leveling screws in use not a console with with long leveling screw legs.  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 12-09-2003 01:02 PM                        The center of the aperture opening (or pinhole) should be on the exact optical centerline of the lamphouse and lens. It's that simple. With cast iron bases, gently prying it into place is less risky than hitting the brittle metal with a sledge hammer. Use a piece of wood to spread the stress of the prybar and not damage the base.  |  IP: Logged Daryl C. W. O'Shea Film God Posts: 3977 From: Midland Ontario Canada (where Panavision & IMAX lenses come from) Registered: Jun 2002 posted 12-09-2003 01:11 PM                        I too have used a crowbar for years to make small adjustments of the base on a screen with a 300' throw. Never had a problem. In fact using a crowbar allows for more precise movement than any sort of mallet.  |  IP: Logged

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