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Author Topic: Scope going off bottom of screen Antonio Marcheselli Phenomenal Film Handler Posts: 1260 From: Florence, Italy Registered: Mar 2000 posted 12-09-2003 02:01 PM                        Uhm, no, it wasn't what I mean. If I center the lamphouse and the len's holder with the center of the lamphouse, I'm sure that my projector is internally aligned, right? My question is: When I thread 35PA I can move its position using the frame knob. If I project the image without aperture plate how can I be sure that the 35PA is perfectly in frame, since I have to use it to center the entire projector on the screen? While I was writing I found the answer by myself: put the align'o'tron in the previously centered len's holder and frame the PA35 until the center of it is on the laser. Right? And what about if I don't have align'o'tron? Frame PA35 by eye don't seems to me the best solution.  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 12-09-2003 02:09 PM                        Do you have a lens jig for doing "string" alignment? On many aperture plates, the horizontal center line of the desired image area is also the horizontal centerline of the plate itself.  |  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 02:29 PM                        You don't frame it by eye looking at the trap, you look at the 35PA image projected on the screen and wall. The outline of the trap acts as an aperture. You know the trap outline in centred, so you just have to centre the framing based on the trap outline as it is projected. If somebody can take a picture of 35PA being projected without an aperture I think Antonio would understand what we're talking about.  |  IP: Logged Antonio Marcheselli Phenomenal Film Handler Posts: 1260 From: Florence, Italy Registered: Mar 2000 posted 12-09-2003 04:54 PM                        Trap is the gate? I understand, but what about when your window is not big enough to project the trap shadow on the back wall? and what about when the 35PA is projected on the ceiling? How can I center the 35PA if half of them is projected on the ceiling? Again, I can reply by myself: put a piece of something (paper?) in front of the projector to project the whole image. I didn't know that the gate outline is reliable to make this adjustments. Did I miss something? Bye A  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 12-09-2003 05:50 PM                     If you have aligned the guides and lateral guide roller to the intermittent sprocket (another issue) then the window of the trap is accurate  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 12-09-2003 06:19 PM                    But that's horizontal and I would think the 35PA/RP40 image would be the most accurate there. It's the vertical position I wonder about since the test film will be naturally affected by framing adjustment. You have to start somewhere so I guess a position halfway between gate or trap components is as good as any.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 12-09-2003 06:29 PM                     Using the trap as a apperture and adjust the framer to centre the 35PA image in that window (I often put a card on the porthole and focus it on that) and that wil be the centre to align the lens mount to and then file to  |  IP: Logged Richard Greco Phenomenal Film Handler Posts: 1180 From: Plant City, FL Registered: Nov 2003 posted 12-12-2003 09:33 PM                     Hey guys, Foud out the problem. It seems that the aperature plates were changed before I got there. I looked at the plate for the projector in question and it said it belonged to projector 1. I go to projector 1 and sure enough, there is an aperature plate that is filled in on the bottom. It works now, but it seems to be too narrow. Any ideas on that?  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 12-15-2003 03:41 PM                        The bottom line is show as much of the image area specified by standard SMPTE 195 as possible, measured using the SMPTE 35-PA (RP40) test film: http://www.kodak.com/US/en/motion/newsletters/pytlak/spring2001.shtml You need the correct focal length lens and aperture plate for each format, to just overshoot the black screen masking that defines the actual image area by a little bit. If people mixed up your aperture plates, lenses, and masking stops, you should ask that a service engineer look at what you have and make the necessary recommendations.  |  IP: Logged Randy Stankey Film God Posts: 6539 From: Erie, Pennsylvania Registered: Jun 99 posted 12-15-2003 04:40 PM                     Richard, Bonus for you! You solved a projection problem and you didn't have to use tools and adjust machines to do it! What do you mean by "...seems to narrow..."? If the rectangle of light coming out of the projector matches up with the edges of the screen/masking it's likely you're OK. (Or at least as OK as you're going to be, anyway.) What some theater builders do to save money is to make a "One-size-fits-all" screen. The sides or top of the screen masking are stationary and don't change when you go from FLAT to SCOPE. (Or vice versa.) The problem is that you end up cutting off some of the sides of the picture when you show a SCOPE movie and you end up cutting off some of the top/bottom of the picture when you are in FLAT. It's a sucky way to do things but you're going to have to live with it and make the best of it. There's not a lot you can do to change things at this point. The easiest way to tell is that when you go from FLAT to SCOPE the picture seems to stay the exact same size. If you're watching a SCOPE movie, when you see credits on the screen they'll probably go right to the edge of the picture, even though you know they're not supposed to. If you're watching a FLAT movie and you are in a closeup shot, it'll look like some of the tops of people's heads are being cut off and parts of their chins are chopped off. Now, if the picture doesn't fit the screen exactly (or nearly exact) they there is another problem. If the aperture plates have been swapped around on the projectors I can't imagine why the same person or persons couldn't have moved lenses around too! If this is the case it could be hard to figure out which lens goes where unless you're up for a fair bit of "trial and error".  |  IP: Logged Richard Greco Phenomenal Film Handler Posts: 1180 From: Plant City, FL Registered: Nov 2003 posted 12-15-2003 05:33 PM                     What I mean Randy is when the picture seems to narrow, I noticed that the plate was filed wrong on the soundtrack side. It was filed at an angle.  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 12-16-2003 09:11 AM                        quote: What I mean Randy is when the picture seems to narrow, I noticed that the plate was filed wrong on the soundtrack side. It was filed at an angle. Your theatre may have some "keystone distortion" (projection beam at an angle to the center of the screen), and the aperture was filed to give parallel image edges on the screen.  |  IP: Logged Richard Greco Phenomenal Film Handler Posts: 1180 From: Plant City, FL Registered: Nov 2003 posted 12-16-2003 10:00 AM                     I did notice that on the port window it is angled to the right. However John, The angle from the plate is really noticeable on the screen. So for right now, I am using another plate that is more open on the soundtrack side and doesn't block the view of the left side of the screen. Any ideas on how to file it so it will fit?  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 12-16-2003 10:05 AM                        You file it to produce an image on the screen that just overshoots your black masking a bit, with projected image area measured with the SMPTE 35-PA (RP40) test film. Again, your service engineer would be the best person to give advice on your particular situation.  |  IP: Logged

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