my profile | my password | search | faq & rules | forum home

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » Rolling loop VistaVision? (Page 2)

This topic comprises 3 pages: 1  2  3

Author Topic: Rolling loop VistaVision? Adam Martin I'm not even gonna point out the irony. Posts: 3686 From: Dallas, TX Registered: Nov 2000 posted 02-04-2004 01:33 PM                     I think Bob was having problems uploading the image.  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 02-04-2004 07:32 PM                    Is there Quicktime (or other format) of a rolling loop somewhere?  |  IP: Logged Adam Martin I'm not even gonna point out the irony. Posts: 3686 From: Dallas, TX Registered: Nov 2000 posted 02-04-2004 08:40 PM                     I posted an animated gif in the Imax Basics thread a couple of years ago.  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 02-07-2004 03:33 PM                     The Jones prototype was made of whatever was found in his shop that day and a bit of Meccano for luck. The one presumably in the disappeared picture was much nicer, with purpose-made parts. As I recall there was also one that could be used as a camera, also 4-35. Either of the two mentioned might have done that though, not necessarily a third model. I think Ron's even had a sort of framing system, that would rotate the entire mechanism relative to the aperture and lens mount with about 6 perfs worth of image actually available. Tough luck if you got 2 perfs out of frame? More amusing were the early 15-70 prototypes, one with a chain system instead of a solid rotor. Bill Shaw said although it never got close to 24fps the chain unit made the most impressive noises of them all.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 02-07-2004 09:42 PM                     "More amusing were the early 15-70 prototypes, one with a chain system instead of a solid rotor. Bill Shaw said although it never got close to 24fps the chain unit made the most impressive noises of them all." Well considering Bill was one of the engineers at CCm bicycles for years no wonder  |  IP: Logged Dick Vaughan Phenomenal Film Handler Posts: 1032 From: Bradford, West Yorkshire, UK Registered: Jul 2000 posted 02-09-2004 02:47 AM                        Hi Dave The silver knob at bottom left of the mechanism is the framing adjustment. You can see the cog meshing with I think a section of chain on the rotor mount. We actually had this version on display outside the booth in Bradford for over a year in the mid to late 80's. The engineering drawing shop at the Science Museum made plans for us as of course none existed back in Oakville. Unfortunately these have gone missing in the shake up in London.  |  IP: Logged System Notices Forum Watchdog / Soup Nazi Posts: 215 Registered: Apr 2004 posted 12-31-2005 03:47 AM                 It has been 691 days since the last post.  |  IP: Logged Paul Trimboli Master Film Handler Posts: 274 From: Perth Western Australia Registered: Dec 2002 posted 12-31-2005 03:47 AM                     Sorry to bring this old thread back up but I have a question. Are you sure the above picture of the Ron Jones rolling loop is not for 8 perf? Its my understanding that between the rotor gaps represents one frame shown twice. So there should be 4 perf opening, flicker shutter 4 perfs wide, 4 perf opening and then the next rotor gap comes in to disengage the frame and the process starts over. Look at that picture using the sprocket as a scale it does not look like 4 perfs spacing in the rotor, although the flicker shutter look about right?  |  IP: Logged Christopher Seo Jedi Master Film Handler Posts: 530 From: Los Angeles, CA Registered: Jun 99 posted 12-31-2005 11:51 AM                     Paul, The actual width of the shutter opening does not depend on the size of the film, but on the size of the rotor. If a rotor of length x cm represents the projection of one frame of film (i.e., we know that x centimeters' worth of rotor will pass the aperture block during the projection of one frame), then the two portions of open-shutter space in the rotor will each be of length x*E/2 where E represents the light efficiency in percent. Disclaimer: I haven't threaded an IMAX projector in four years, much less a 4-perf one!  |  IP: Logged Paul Trimboli Master Film Handler Posts: 274 From: Perth Western Australia Registered: Dec 2002 posted 01-02-2006 06:10 AM                     Thanks Christopher! There is going to be limitation due to travel ghost of just how large the opening can be (meaning you can't have a projector 100% light efficent), any idea on they work that out?  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 01-02-2006 10:26 AM                     Travel ghost on a rolling loop is virtually impossible aslong as the pocket for the loop to form in is holds one frame  |  IP: Logged Christopher Seo Jedi Master Film Handler Posts: 530 From: Los Angeles, CA Registered: Jun 99 posted 01-02-2006 08:00 PM                     Right, the film transport function (i.e. the pockets) is so tightly integrated with the shutter function (i.e. the openings) in the rotors that they are sort of mutually exclusive... you couldn't really produce travel ghost if you tried. The light efficiency still depends on how fast the frame-change can be accomplished, as with conventional movements, only you can't "cheat" on a rolling loop by introducing some travel ghost to improve the light efficiency like you can on regular projectors where the shutter is an entirely separate piece. It's got me thinking though... what if ya backed the pockets with glass? As the film gets peeled off the field flattener it'll go way out of focus, so maybe it won't be very noticeable... but I assume if that idea worked it would have been implemented.  |  IP: Logged David Kilderry Master Film Handler Posts: 355 From: Melbourne Australia Registered: Sep 1999 posted 01-03-2006 05:13 AM                        Not a bad effort for an Australian projectionist/engineer fooling around in his Brisbane backyard workshop! Ron Jones apparently spent several years in the 1960's working on the rolling loop before presenting a paper on the subject. Ron was a self-trained engineer and cinema technician, who rebuilt and repaired projection equipment. He ran tests with the rolling loop mechanism at the Eldorado Cinemas in Brisbane; today this cinema still operates and has been enlarged to an 8-plex.  |  IP: Logged Dick Vaughan Phenomenal Film Handler Posts: 1032 From: Bradford, West Yorkshire, UK Registered: Jul 2000 posted 01-04-2006 09:21 AM                        quote: Paul Trimboli Are you sure the above picture of the Ron Jones rolling loop is not for 8 perf? Absolutely certain. Look at the top sprocket with the cross marked on it for frame alignment. You can count the teeth between the lines. As i said we had custody of that piece of equipment for quite a while here at the Museum.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 01-04-2006 10:50 PM                     Ok, A little closer look......  |  IP: Logged

All times are Central (GMT -6:00)

This topic comprises 3 pages: 1  2  3

Printer-friendly view of this topic

Hop To: Select a Forum: Category: Operations -------------------- Digital Cinema Forum Film Handlers' Forum Large Format Forum Ground Level Feature Info, Trailer Attachments & REAL Credit Offsets Category: Community -------------------- Film-Yak Film Handlers' Movie Reviews The Afterlife Bob Maar's Joke-A-Thon Category: Classified -------------------- Equipment and Supplies Wanted/For Sale Help Wanted/Seeking Employment Category: System -------------------- Software Beta Testing Forum

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.