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

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » Periscopic projection (Page 1)

This topic comprises 4 pages: 1  2  3  4

Author Topic: Periscopic projection Peter Schoell Film Handler Posts: 47 From: Paynesville, MN, USA Registered: Jul 2001 posted 05-30-2003 10:54 PM                     I know film has been projected through periscopes with 2 parallel mirrors.Can this be done with 2 mirrors that are at right angles to each other? I'm looking to build an auditorium in which the film path would travel in a "U" shaped path. Because the mirrors aren't parallel, will I be able to hold focus across the screen? BTW, George Bush assures me periscopic is a word.  |  IP: Logged Tim Reed Better Projection Pays Posts: 5246 From: Northampton, PA Registered: Sep 1999 posted 05-31-2003 12:14 AM                       If you're talking about a vertical distance, you won't have to worry about focus... the second mirror rotated top-to-bottom about the light path will flip the image. If you can, turn the projector in the direction of the screen, and then use the periscope to get the beam around to where you need it. Not sure about horizontal periscopes, if that's what you're asking, but I would think you'd have the same situation - only with the image flipping sidewise.  |  IP: Logged Tom Kroening Expert Film Handler Posts: 214 From: Janesville, WI USA Registered: Oct 1999 posted 05-31-2003 01:10 AM                     From what I've heard these parascopes are more trouble than they are worth. I would think image stability would be a problem as well as getting a sharp focus. I'm sure it could be done but isn't there any other option?  |  IP: Logged Per Hauberg Jedi Master Film Handler Posts: 883 From: Malling, Denmark Registered: Jul 2000 posted 05-31-2003 05:29 AM                        Do i remember it right: was it between 30 and 40 % loss of light in one set of mirrors ?? Per  |  IP: Logged Kevin Baglow Expert Film Handler Posts: 135 From: Yeppoon Qld, Australia Registered: Dec 2000 posted 05-31-2003 06:22 AM                        Some one north of here has been doing it for about 10 years. They are finally coming to there sensers and building the projection in the right place. they said the horizantal lines in the picture became bowed.  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 05-31-2003 08:09 AM                        There are many downsides to using mirrors. You must use optical-quality front-surface mirrors. Unless kept perfectly clean, the picture contrast will be adversely affected. Any vibration of the mirrors is magnified, and will appear as unsteadiness. There is a light loss at each mirror surface, which will depend upon the type of mirror and how clean it is.  |  IP: Logged David Stambaugh Film God Posts: 4021 From: Eugene, Oregon Registered: Jan 2002 posted 05-31-2003 12:09 PM                        Moyer's old Valley River Twin here in Eugene used mirrors. I only went there once. It's probably safe to say they were not paying a whole lot of attention to little things like cleanliness or alignment of those mirrors. What a horrible theatre - skanky in all respects. Luckily the place was eventually demolished and replaced with a Red Lobster restaurant.  |  IP: Logged Greg Mueller Phenomenal Film Handler Posts: 1687 From: Port Gamble, WA Registered: Jun 99 posted 05-31-2003 12:40 PM                        Astronomical first surface mirrors have coatings that will get to about 96% efficiency. "Periscopic" appears in "Websters Encyclopedic Unabridged Dictionary of the English Language" Copyright 1996 page 1442  |  IP: Logged Joe Beres Jedi Master Film Handler Posts: 606 From: Minneapolis, MN, USA Registered: Nov 2000 posted 05-31-2003 01:15 PM                     I have seen a few theaters that projected film off of mirrors, and the presentation was always subpar. Why is it necessary? Can you tell us more? There are some ingenious perople here that could possibly come up with some other viable suggestions, If you really need to do it, I think you would definitely want to invest in some first surface mirrors and some very sturdy mounts. It would be a big investment though.  |  IP: Logged Greg Pauley Expert Film Handler Posts: 173 From: Huntington, WV, USA Registered: Jun 2000 posted 05-31-2003 01:47 PM                        I have two auditoriums using mirrors since the mid seventies in small houses. These two auditoriums were built under a balcony and there was no option to raise the booth higher to get the proper angle to miss people’s heads without the mirrors. We really haven’t had that much problems with them over the years except for the light loss which causes you to run a larger bulb size. I don’t have any problem with image stability since the mirrors are mounted to the wall and ceiling in a very sturdy mount. I would never use mirrors unless there wasn’t any other option, but I wouldn’t be afraid to use them again if I had too.  |  IP: Logged Stephen Furley Film God Posts: 3059 From: Coulsdon, Croydon, England Registered: May 2002 posted 05-31-2003 03:04 PM                     Two of London's main railway stations had 'news theatres' built in the '30s. The one at Victoria closed about twenty years ago, the one at Waterloo some time earlier. In their later days after the newsreels finished they ran cartoons. Originally they had slide lanterns to project train times and announcments on a small screen alongside the main one. One of these, Waterloo I think, had the projection box built above the auditorium, with rear projection via mirrors, but it was later changed to a more conventional set-up, so I assume it didn't work too well. Bernard, if you read this, do you know any more about these places? Both have now been demolished, and I never went to the Waterloo one. I was taken to the Victoria one when I was quite young, and I remember seeing a Laurel and Hardy film. I had never heard of L&H at that time. The following day it was anounced in the papers that Stan Laurel had died. Was anything similar to this built at any of the American stations? I went to the Victoria one on its last night, I think it was still Academy ratio only, until it closed, if I remember correctly. They were still using the original projectors, but wouldn't let anyone up to the box to see them until an original nitrate print of a newsreel from its opening year which they ran a couple of times had been removed. I had to leave to get somewhere else before this was done, so I didn't get to see them. The place was quite interesting architectually, but was demolished very soon after closure as part of a shopping development above the station. The plainer Waterloo one remained, unused, for many years after closure.  |  IP: Logged Mark Lensenmayer Phenomenal Film Handler Posts: 1605 From: Upper Arlington, OH Registered: Sep 1999 posted 05-31-2003 03:58 PM                     Two 70's vintage AMC theatres here used periscopes. They did this so they did not have to put in a second level for a projection booth. The projectors sat level with the back of the theatre, then went up about 5 feet to clear the heads of the audience. I believe they stopped that practice by the '80's. These were the early AMC shoebox style theatres. They were both 6-plexes and seemed HUGE at the time.  |  IP: Logged Tim Reed Better Projection Pays Posts: 5246 From: Northampton, PA Registered: Sep 1999 posted 05-31-2003 07:47 PM                       TransLux used to have mirrors -- they were rear-projection, too; albeit their mirrors were in the lens barrels. And Plitt in Houston used to use a periscope arrangement to get over the corridor. Every time someone opened the door to the auditorium, the picture on the screen would go <wobbbbbobobobllllle!> I've seen them in a bunch of drive-in twin-splits. No, mirrors are never a good idea.  |  IP: Logged Peter Schoell Film Handler Posts: 47 From: Paynesville, MN, USA Registered: Jul 2001 posted 05-31-2003 08:59 PM                     Wow! Thanks for all the input. I have 2 reasons for putting in a screen with a periscope. 1) One of my theatres has a small store front as part of the building. I've had it rented about 5 times in the last 7 years and collected about $300.00 total! So I figure I can put in a small screen ( 14 feet) and about 40 seats, even if I only sell 300 seats a month that's $1200.00, also I don't have the empty store space, which is kind of an eyesore. 2) Also in this town is a drive-in that has 5 screens, an 85, 50, and 3 30ft screens. Since the movie companies will alow a drie-in to stack movies, and since they won't allow us to play the same movie at the same time, this means the drive-in can tie up 10 movies at a time. The movie companies usally give me first choice, but in the summer, when we have so many tittles opening each week and then having to hold them for 3 weeks, I sometimes have to pass because my three screens are full. The drive-in will take the film and hold it until labor day, this is what happened with Jurrasic Park 3 a couple of years ago. I ended up playing J3 after Labor Day for 1 pitiful week. I also end up terminating films before i'd like just so I can open something else and pay those first week percents, which are more than driv-ins get charged, but that's another topic. The room I'm planning will have about 40 high back rockers, small risers, probaly 6 inch, and center surround. I plan to put the projector in the basment under the auditorium, and run the periscope up the back wall. I'm sure the manager will be overjoyed when she finds out she'll have to run upstairs to rethead 3 rooms then down to the basment to rethread the fourth. As all employers know, employees are always looking for new challenges. OK that's another topic too.  |  IP: Logged Richard Fowler Film God Posts: 2392 From: Ft. Lauderdale, FL, USA Registered: Jun 2001 posted 06-01-2003 04:49 AM                     Your will find your mirror in the auditorium will be quite large. A simple trick is to scale out your projection throw with some graph paper and fold the paper at the distance points for the mirrors to give you a general of the size required. The smaller mirror should be front surface glass and the second mirror should be optical mylar on a frame due to the larger size. These mylar mirrors are available from Hudson Photographic in New York or Vutec in Florida. Another option is to do what Hoyts in Argentina and SK in Sweden have done...build a tunnel / chamber to allow projector and lamphouse on a custom mount to travel up a lift to the auditorium after threading. The Platter and sound stay in the basement. The chamber would take the space of about two seats. I have personally done this for an 8-70 installation to move back the projector to a thread position and send it up a tunnel 14 feet for projection. Richard Fowler Kinoton America Inc. A little jet lagged this morning..........  |  IP: Logged

All times are Central (GMT -6:00)

This topic comprises 4 pages: 1  2  3  4

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.