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Author Topic: 5/70? 8/70? 15/70? Richard Greco Phenomenal Film Handler Posts: 1180 From: Plant City, FL Registered: Nov 2003 posted 01-15-2005 01:41 AM                     Can someone explain these numbers to a 35mm guy? I know the 70 means 70 mm, but what do the rest mean?  |  IP: Logged Paul Mayer Oh get out of it Melvin, before it pulls you under! Posts: 3836 From: Albuquerque, NM Registered: Feb 2000 posted 01-15-2005 02:18 AM                        The number of perfs defining that dimension of the film frame. So 570 is five perfs high, 870 is eight perfs high, 1570 is 15 perfs wide (1570 runs horizontally).  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 01-15-2005 02:57 AM                     quote: Paul Mayer 870 is eight perfs high, 1570 is 15 perfs wide (1570 runs horizontally). or...5/70 is your usual 70MM, 8/70 is the vertical film run SuperScreen, and the 15/70 is the IMAX/OmniMax presentation. Here's some pics of 5/70 and 15/70 IMAX. The 5/70 is from "Dr. Dolittle" and the 15/70 is from that Space Shuttle show (forget the title). the 5/70 the 15/70 Sound for the 5/70 is on the magnetic tracks containing the standard six channels, whereas the 8/70 and the 15/70 uses a digital sound dubber that runs in sync with the film. -thx Monte  |  IP: Logged Dick Vaughan Phenomenal Film Handler Posts: 1032 From: Bradford, West Yorkshire, UK Registered: Jul 2000 posted 01-15-2005 04:45 AM                        5 /70 prints can also carry DTS code in place of the mag tracks and have in the past had digital soundtracks (CDS) 8/70 and 15/70 can also be synchronised with 35mm mag tracks, 1/2" 8 track,multi CD ( IMAX DDP) and DTS. And I am sure that Messrs Hill and McLeod can add to this In fact Phil probably synchronised 1570 to Vitaphone discs in his youth  |  IP: Logged Richard Greco Phenomenal Film Handler Posts: 1180 From: Plant City, FL Registered: Nov 2003 posted 01-15-2005 10:58 AM                     Thanks Guys, now I understand.  |  IP: Logged Darryl Spicer Film God Posts: 3250 From: Lexington, KY, USA Registered: Dec 2000 posted 01-15-2005 11:51 AM                    ....and if you notice on the 15/70 example strip the jagged cut on the left side. This is done to reduce the tendancy of the film pulling away from the splice do to the tension caused by the speed at wich the film flows.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 01-15-2005 12:53 PM                     quote: Darryl Spicer This is done to reduce the tendancy of the film pulling away from the splice do to the tension caused by the speed at wich the film flows. Actually it allows the film to flex without making a sharp bend as a straight splice might do. This is very important in a rotor based projector of any gauge where the rolling action of the film might cause a straight splice to bend 90 degrees and cause a resultant pile up in which severe damage may result to the projectors claw mechanism. Mark  |  IP: Logged Adam Martin I'm not even gonna point out the irony. Posts: 3686 From: Dallas, TX Registered: Nov 2000 posted 01-15-2005 01:17 PM                     Claw mechanism? What awful projector uses a claw mechanism?  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 01-15-2005 03:38 PM                     The "claw mechanism" is used in Imax 15/70 projectors (I'm not sure about the new one, but it probably does) and in all the other large format rolling loop systems I've seen. This claw does not do the frame advance, the rolling loop takes care of that. The film is set on stationary registration pins around the projection aperture when the loop rolls past; this changes frames quite rapidly. As well as having a loop formed and dissipated 24 times a second, the film is moving through the projector at 337.5 feet/min. Just laying it onto the registration pins would require the film's mass to be decelerated by the registration pins - and would damage the registration perforations slightly. After repeated passes the accumulated damage would make the screen image quite shaky horizontally. To prevent damage to the registering perforations a "claw arm" engages film perfs a few away ("before" if you look at the projector but "after" in the sense of film time) from the leading registration perfs. The arm is actuated by a cam system so that the pins enter the perforation at the same speed as the film motion, then decelerate relatively gently until the film is almost stationary as the registration pins are engaged. A properly adjusted Imax projector will run a film loop for thousands of passes with no perforation damage.  |  IP: Logged Adam Martin I'm not even gonna point out the irony. Posts: 3686 From: Dallas, TX Registered: Nov 2000 posted 01-15-2005 08:18 PM                     Oh ... you mean the CAM and CAM ARM. I have never heard anyone call it a "claw mechanism", so I read it to mean a claw mechanism that advances the film, such as in an camera. (And let me tell you ... the claw mechanism in an Imax camera is something to behold!)  |  IP: Logged Phil Hill I love my cootie bug Posts: 7595 From: Hollywood, CA USA Registered: Mar 2000 posted 01-16-2005 07:48 PM                  Adam: I cannot believe it! You are soo naive! Dave said it best and eloquently explained what was meant by the term "claw" and its function as it pertains to a rolling-loop projector. I'll have to go and look at my copies, but I believe that it is referred to as the "deceleration cam, arm, and CLAW" in the patent as well. Gosh! For a mod, you sure are a dumbass sometimes! HA! (Am I banned yet?) Hugs, >>> Phil  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 01-17-2005 01:56 PM                        Just a few of the US Patents for the IMAX projection system: U.S. Patent Documents 3494524 Feb., 1970 Jones 3600073 Aug., 1971 Shaw 3794415 Feb., 1974 Jones 3944349 Mar., 1976 Jones 4039256 Aug., 1977 Teeple et al. PAT. NO. Title 1 5,050,985 Film deceleration unit 2 4,997,270 Projected image alignment method and apparatus 3 4,993,828 Camera and method of producing and displaying a 3-D motion picture 4 4,971,435 3-D motion picture projection apparatus 5 4,957,361 Method of producing and displaying a 3-D motion picture 6 4,441,796 Film support element assembly 7 4,406,519 Projection screen assembly 8 4,365,877 Field flattener lens element assembly 9 4,114,996 Inlet guide structure for rolling loop film transport mechanism  |  IP: Logged Phil Hill I love my cootie bug Posts: 7595 From: Hollywood, CA USA Registered: Mar 2000 posted 01-17-2005 03:20 PM                  Oh yes. Thanks John for reminding me. I'd hate to say how many times I was in court and/or gave depositions about those patents. Ummmm, of why we were not infringing. The one that still kills me to this day and I still have nightmares over is: 4,365,877 Field flattener lens element assembly. I could NEVER figure a way around it without using a septum! DAMN!  |  IP: Logged Randy Stankey Film God Posts: 6539 From: Erie, Pennsylvania Registered: Jun 99 posted 03-16-2005 05:28 PM                     quote: Dave Macaulay To prevent damage to the registering perforations a "claw arm" engages film perfs... So, this cam/claw mechanism operates in similar fashion to the claw in a sewing machine that advances the fabric under the needle, except in reverse? (It slows the film down rather than pushing it along.)  |  IP: Logged Thomas Dieter Expert Film Handler Posts: 234 From: Yakima, WA Registered: Jun 2004 posted 03-16-2005 07:43 PM                     WOW, I have to say that all this information that everyone has just posted, just made me want to operate an 870, and a 1570 projector more than ever. I've watched 1570 film being threaded in an OmniMax projector before, and even had the guts to ask to come in and look at the projector(I got denied). I think was it is that facinates me about this film is the fact that it is so large, and the way it is handled is amazing. The zigzag splice? I under stand how it works and all, and it's a great idea. What my question is, does the appature plate cut out the zigzaged area so that the film doesn't look to bleed on one side of the screen, or do you have to take and cut your splice back one tooth? Also to go with that question, would a / spice work too? The drive in theatre that I use to work for had a splicer that was able to make | and / splices. And this should go in another thread and what not, but beings that I've touched on it already, what's the purpose of the / splice?  |  IP: Logged

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