What I REALLY want to see is a picture of the IMAX projector. Nothing too fancy... just something like, "The film goes in here, through this doohicky, around this thingamabob then comes out here. (Or whatever.)

Is there some kind of patent/trade secret thing that prevents people from showing that?
 

Click Here

(remember to click on the red oval SDDS icon)

with the left and right channels on the walls. interesting

In this case, it seems like there was absolutely no communication whatsoever -- don't just look at the SDDS -- that diagram was used throughout the movie sound article. Not only doesn't it show the additional screen channels for SDDS; it also seems to believe that Dolby Stereo has only two channels and has completely left out the left and right surrounds. But I suppose we can't expect all illustrators to be experts on motion picture sound.

------------------
Tao Yue
MIT '04: Course VI-2, Electrical Engineering and Computer Science
Projectionist, MIT Lecture Series Committee
 

"The Rolling Loop -- A New Concept of Film Transport", by P. R.(Ron) W. Jones, SMPTE Journal, January 1968, pages 21-23

"Film Dynamics of a Rolling-Loop Film-Transport System", by William C. Shaw, SMPTE Journal, September 1970, pages 778-782

"New Large-Screen and Multi-Image Motion-Picture System", by William C. Shaw, SMPTE Journal, September 1970, pages 782-787

Technical achievements like this make you proud to be a member of the SMPTE.

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

other things he explains on the site can be somewhat more complex. a question was submitted concerning what makes super glue so super ( http://www.howstuffworks.com/question695.htm ). he went into the main chemical makeup and how it reacts to make polymer bonds and what not. i mean, its basic chemisty but if you know nothing about chemistry in the first place, then its a good thing to get a brief explanation.

ok, time to get some chow.
 

I don't think that there are patents/whatever preventing people from showing the IMAX projector. Direct your 56k modem to the "VIDEOS" section of this site and click on OMNI THEATER. Be sure to download the big 139 meg Quicktime and you will see the IMAX (actually OMNIMAX) projector in all its glory.
 

If it's just a few articles, I can send them to you. I have some issues, but only back to 1945 (SMPE!).
 

John Walsh is correct that the SMPTE is in the process of putting articles on their website. For now, they have put indices and more recent articles and presentations "on-line". You can join the SMPTE and subscribe to their library service at:
http://www.smpte.org/membership/

The SMPTE "members only" library is at:
http://www.smpte.org/members_only/

You can work with your local library to get copies of articles published in the SMPTE Journal. Libraries that subscribe to the SMPTE Journal would include film schools (e.g., UCLA, USC) and science/engineering schools that teach film or television technology (e.g., Rochester Institute of Technology).

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion
 

- Only a few very old water cooled Imax/Omnimax systems use 12kW lamps. Since around 1985 or so all have been 15kW. There are a fair number of 4 and 4.5 kW air cooled ones as well, and one or two 7kw (maybe, if they are still running and have never upped to 15kW) aircooled "classic" machines.
There are 2 Imax "Solido" 3-D single case 2-strip cameras with a fixed interocular, dictated by the lens diameters when it was designed. With 1000ft magazines it's probably in the 240 pound range. There can also be a 3D rig with 2 "standard" MK1 Imax cameras at 90 degrees with a 45 degree mirror. This thing weighs a bit more, and has a gyro stabilized mount available that probably weighs as much again. The first 3D Imax film, made for Expo86 in Vancouver, used this one. Imax doesn't seem to want to admit to this movie, it isn't on their film list and I can't even remember the name. Transitions? It had the teddy bear scene, and the robot arm breaking an egg in your lap. The twin rig was used on The Last Buffalo and also Imagine - if that's the one with the little people - as the freedom to mess with interocular was needed for that effect. There was also a 3D rig with the cameras about 6 feet apart for some weird forced shots.
There are many problems with the mirror rig - it takes a LONG time to set up using reticles projected from the cameras onto a screen for alignment. This needs a large dark area, obviously... Plus, the amount of cabling and electronics is a nightmare.

- The author talks about 48fps as if it's a standard feature. Not. There are almost zero 48fps films and only a few more projectors that can show 48. Ontario Place and Hull are the only ones I'm sure of. The cameras get very snarky if expected to run at 48 for long (it's about the limit for the standard camera) and the projectors like it even less. The film is moving twice as fast, and has to be stopped and accelerated again every frame. The inertial energy is proportional to the square of the velocity...

- 20 minutes to reload? Nonsense. The 3D one maybe, but a decent camera operator can do a 2D mag change in about 5 minutes maximum - with a good cleaning thrown in. We can't count the time to reload the mag, an assistant does that in a dark bag during shooting.

- 3 minute rolls? OK, but there are also 2000' (6 minutes...) magazines and Kodak did supply 2000 foot 65mm neg rolls. These were made for the Stones movie, to cut by half the mag changes. Filming theirive show apparently made the effort worthwhile. There are also 300' mags for shots where weight or size is a problem, they were used in the infamous Catch the Sun skydiving shoot that may have financially saved Imax in the early days.

- There are lots more than 2 cameras of course. Camera #2 was the one used trying to parachute but there were about 8 working ones the last time I looked. 2 of these were reserved for only spaceflight though.

- There are at least 2 very different generations of 2D Imax camera, the solido Imax3D ones, plus as the competition's 15/70 models) which we shouldn't call Imax of course).

Plus, it didn't even really tell us how it works!

I have a bunch of photos somewhere, if I get ambitious I will try to find one that shows the front end of a projector. If anyone (Gord?) can scan a threading diagram from a manual that would be excellent!

I am pretty sure that Sony Lincoln Square (NYC) is 48fps-capable.

I mentioned the 12k because the Detroit Science Center just re-opened with a new 15k lamphouse that almost doesn't fit in their doghouse. I forgot about the 4k and had absolutely no idea there was a 7k classic!

I can't think of where 48fps capable systems might be other than Hull and OP - ?
 

"Momentum" was the 48fps IMAX film at EXPO 92 in Seville.
CLICK HERE

The NFB and Giant-Screen Filmmaking http://www.nfb.ca/E/4/2/imax.html

The above image is an animated gif, so Joe needs to turn on his animations.

As the film enters the projector at the input sprocket, a burst of air "encourages" the film to form a loop in the rotor gap. The gap is actually a "pocket" in the rotor, so that it also acts as a shutter.

As the loop approaches the aperture block, it increases in size to 15 perfs (1 frame).

As it reaches the aperture block, the cam pins retract and return, "catching" the tail of the loop and decelerating the film. This aligns the perfs with the registration pins as the loop rolls across the face of the field lens, where it is sucked into place against the registration pins and projected.

A flicker shutter passes across the light field and the same frame is projected again (the same effect as the bow-tie shutter in a 35mm projector).

After the next frame is rolled across the field lens, the loop gradually diminishes in size as it exits the projector via the output sprocket.

The film is not moved in an intermittent movement, but is looped and rolled by the rotor through the projector. Imax calls this a "rolling loop". Iwerks calls this a "lateral loop" because it is a horizontally moving loop (and Imax used "rolling loop" first).

Incredibly over-simplified, but there it is.

For GT-3D, take two rotors, stack them on top of each other, and lock them together with a 11.25-degree offset. The right eye projects while the flicker shutter passes the left eye.

For SR-3D, take two projectors and interlock them with a PLC.

Gord: Now that makes more sense than what I was seeing. I was seeing the cam pins as a "holdback" so the loop could enlarge, but now I can see it catching the tail of the loop to allow the film to align with the registration pins on the aperture block. If I pull back the stator and turn the rotor by hand, I see the registration pins are holding back rather than the cam pins.

Wow ... that's two days in a row I learned something new!

 

Contrary to the previous mis-information, Iwerks has both 24 and 48 fps projectors and refers to it's 1570 projector as a "rolling loop" projector, which it is. Iwerks also has several 870 and 1570 cameras in both 2D and 3D configurations as well as underwater housings, helicopter mounts, etc.

The linear speed of the 15 perf, 70mm film at 24fps is 337.5 feet per minute and 675 ft/min at 48fps (Like at Disney's Soarin'). That's about 3.8 and 7.6 miles per hour.

Think about it.... the projector is stopping and projecting and accelerating the film at those rates while projecting a rock-solid image without damage to the film!

A typical 24fps, 40 minute 1570 print is 2.5 miles long and costs about $20,000.

A standard 35mm feature runs about 1.0 mph and the print costs about $1500-$2000.

YIKES!!!!!

>>> Phil

Brad, is it possible to put Adam's illustration and explanation available for download in "manuals" or "pictures" along with a representative full size three frame segment of the film itself and image of the head?

Jerry, one frame is exactly the size of the shuttered rotor gap. The edges of the shutters on the gap match the frame lines. The loop is not a full frame in size until it rolls onto the field lens and then it immediately begins to reduce as it registers and exits the field lens.

As the film passes the input sprocket and enters between the rotor gap and the input stator (the guide on the non-rotor side of the film), a jet of air pushes the film against the stator while the input sprocket feeds film into the loop. (This causes a loop form into the rotor gap rather than a wad of film at nearly 6 feet per second. [There is a reason why we call them film "crashes"]) The air lasts just long enough for the loop to take shape, then the loop enlarges without any further assistance (other than being fed by the input sprocket) as it travels along the rotor.

Also, I have slowed down the animation on the graphic above. You may have to refresh.

Brad, if you want to post it for reference, at least let me do a better looking one on my good computer at home. I may also do one later today for the loop being formed.

 

With a service contract, I would say that if there is anything endangering the print or significantly hindering the presentation, don't run the show. Without a service contract, I guess it depends on how much money your boss wants to spend/lose.

In the 35mm world, I've had projectors temporarily held together with duct tape, baling wire and vice grips to keep the show on the screen. And I think just about everyone's spun a platter or two by hand for an hour to make it to the end of a show.

If it comes down to the show *can't* go on, the I try to look for another option before cancelling. Switching auditoriums, cancelling a slower movie, swapping prints with a slower complex in the same circuit. Whether or not you like the manager on duty can have an effect, too.

 

Look above or look below. Either way, make sure you refresh.

Also, keep in mind that the rotor is moving just one frame per gap. On a GT, there are 5 or 6 frames between the input sprocket and the aperture block, depending on how you count it. I think it's the same on an SR, but it's been a while.

Don't get me wrong, you've got a good illustration for the mechanically inclined, I just wonder if it can be made to show the concept to the lay public by adding just a little more detail. Bravo for taking on the project in any event.

this is a search engine for the US patent database http://www.uspto.gov/patft/index.html
for the older stuff you need to down load a special TIFF viewer. The one netscape and IE wants you to download isn't free but if you click on the patent offices help button there is a link to a free one
 

The loop being formed on the input side of the aperture, and the loop collapsing on the output side makeup the film-speed difference between the constant speed spockets and the stopped (projected) frame.
So the film actually "slides" along the rotor at various speeds between the constant speed sprockets and the frame stopped on the register pins.

Iwerks "Linear Loop" technology is very different than the "Rolling Loop" technology and has it's own patents and Academy Award. Iwerks 1570 projector is the Rolling Loop technology and the Linear Loop is used in the 435, 835, 570, 870, and 1070 formats.

>>> Phil

Use the animation as a "general idea" sort of thing. Here are the patents Gordon mentioned above. These are in .pdf format and you need Adobe Acrobat Reader to view these, but if you've visited the manual warehouse, you already knew that.

3,600,073 Rolling Loop Film Transport Mechanism [18 pages, 1256 KB] August 17, 1971: A rolling loop mechanism for transporting photographic film through a motion picture apparatus.

3,794,415 Rolling Loop Transport Mechanism [7 pages, 395 KB] February 26, 1974: A mechanism for transporting photographic film past an aperture in a projector, camera or other motion picture machine.

4,114,996 Inlet Guide Structure for Rolling Loop Film Transport Mechanism [6 pages, 433 KB] September 19, 1978: Inlet guide structure is provided having complementary outer and inner guides which are adapted to receive film from a drive sprocket of a rolling loop film transport mechanism and to guide the film inwardly towards a path defined between the stator and the rotor of such a mechanism.

I excel at that. Guess that was why I was a D.M., or maybe I learned it from being a D.M. Anyway, I didn't mean to do that and I know you put a lot of work into the animation and should be proud of it.
 

Doing the animation was a good thing for me anyway. I learned something new and now I have something to use when I get asked "So, tell me ..." for the millionth time.

Now I just need to print out each frame and make an animation flip-book I can carry around. Come to think of it, we're a 3D theater. An anaglyphic flipbook would rule!

 

Ron Jones was a cinema engineer of high standing, dureing the early part of the war (ww2) he designed and made 6, 35mm projectors for the army entertainment corp, I have 2 of these machines (all the others have been destroyed)as built with their short bases so they would fit into trucks,they also had AC arcs.These machines still run perfectly.
Not bad for a man from Brisbane Australia

------------------
ALL PARTS FOR VICTOR AND KALART VICTOR 16MM PROJECTORS.
SERVICE TO 35 AND 16MM
PROJECTION EQUIPMENT.
 

My point about showmanship is more about the "premium" 35MM theatres with stadium seating, digital sound, giant screens etc. We all know that the performance can be quite awful- from sound dropouts, blown channels, maladjusted/flickering/dim light to dirt encrusted prints or a screen decorated with coke and gummi bears. Does anyone ever tell the customers there's a problem? Or, as I expect, quietly deal with the occasional complaint while counting the money?
I was at an AMC show (I only go to the big houses with rear exits because it's easy for me to go in the booth and fix focus or other simple problems) and the operator had to focus severely at startup. I knew the Millennium gate was in to far and would snap into index soon. It did, at the "feature" snipe. I waited to see what happened, as about 200 people sat on their butts. For 10 minutes. I know someone would have complained eventually, of course (hope so anyhow). I went up and focused it. (OK, I turned the sound up a bit too)
This isn't to complain about the operator, AMC, the projector, or anything like that. Just to illustrate that most people don't complain, they will endure a really bad show. BUT they won't be coming back and parting with $11.00 very soon.
"The Show Must Go On" drives people away to the video store.
If told there is a technical problem and the film is dirty, the sound is not 100%, or whatever, I might decide not to go in but I would appreciate that they respect me and want me back, and I would go back. I've only ever seen that kind of notice in changeover houses with a dead machine, letting patrons know there will be breaks between reels.

The crappers have little papers that have the time of the last inspection.
How about ones with "last lamphouse/illumination check" "last A- / B- chain alignment" at the box office window?
 

(hope i did ok, this is my first post, well actually third, but the other two didnt seem to work.)
 

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion
 

Spokane's IMAX has a Classic RLP projector running a 4.5 Kw Bulb, But the light output is much better than that of an SR projector. I am not sure if it is because of the horizontal orientation of the bulb compared to the Vertical orientation used in SR projectors. We have system #9. When the worlds fair was held in Spokane in '74 they used System #3 and the theater was located in a location adjacent to the the present location of the theater. We also have the only print of "Man Belongs to Earth" in existence. Currently we are running Beauty and the Beast on an oversized platter with DTS. And the theater Converted to a Mark II platter system to accomodate Fantasia 2000.
I just thought I would give interested people info.
 

What Dave was saying about the air jets was very understandable. I have one question though: Is the Lack of air pressure at the rotor gaps during ramp up the cause of those Strange scuff marks on the film shortly after the Picture Start frame on the Acad. Leader??? My boss is always talking about how bad it would be to lose air pressure during the show, But I think that vacuum would be more critical. But, I could just imagine how badly the film would be scuffed if the projector was to lose air.
Oh and one more thing, He also says that our machine is capapble of running 48Fps, but I am not sure about that. I can see no marks on the Cam assembly to determine if it truly is capable. Can anyone tell me what to look for???

Thanks!
Tristan
 

I've not used a Classic, but both the GT and the SR have air as soon as the rotor starts turning. I don't see why the Classic would be any different, but apparently it is.

Rotors are very unique in that some will scratch film easily without air and some won't. In Tulsa, the SRs didn't; in Dearborn, the GT didn't; here in Grand Rapids, the SRs do. A lot of factors apply here, including booth humidity and the application of PhotoGard.

Here's a sample of an air jet scratch. It's in the shape of an arrow pointing away from the direction of film travel (picture is upside down); individual marks can be light to the point of be unnoticeable or heavy enough to dig through the emulsion. The rotor side of the film is rubbed against the air jet when the center of the film is bowed as the loop forms. The edges don't scratch because the stators and rotor segment rails don't let the film go anywhere it's not supposed to be.

Losing air pressure during a show will scare the living crap out of you. It will also severely scratch film on the air jets if you have one of those rotors that scratch film when you turn it by hand. When a GT E-stops, it immediately turns off the rotor air; on an SR, the entire system remains powered until the rotor has stopped.

The vacuum isn't as important as the air jets are (regarding scratches). All the aperture vacuum does is suck the film against the registration pins and hold it against the field flattener to be projected. I have not seen film damaged due to lack of vacuum, though I haven't exactly conducted a scientific study. I have seen an SR run without a field flattener, though the picture was all over the place and it made quite a racket. I wouldn't try that one at home.

Somewhere I saw pictures of a GT-HD projector and seem to remember a bit of extra stuff under the hood. I don't know what changes would be necessary on a Classic, though I'm sure Gordon could answer that one. I think his projector has probably seen other frame rates.

Got a few other questions about the system.

Does Imax make a Cue detector system that can be retrofitted to the older projectors so that you can place projector stop cues on the film?? I have seen a projector tail out once - not a pretty sight.
Additionally - My supervisor is considering a DDP II system to replace the DTS and Dubber - Would this be a cost-effective way to improve sound quality? Right now, when using DTS - we cannot add trailers to the film unless DTS has put them on the CD along with the feature soundtrack. We had used a D-TAC system in the Boise Imax, and I was very impressed with the Showlist setup.
My concern is this - On a new system, the D-TAC is tied into the automation of the projector and can control show start and ligts etc..... So how easily is the new system adapted to this old Projector with no automation whatsoever?

One more question:
My boss has asked me to find a way to set up a switch to change between the DTS system and the Dubber. Right now we have to go behind the Rack and change some XLR's and the Tach connection. I was thinking about using a bunch of P&B relays to do the job and have them all tied into a toggle switch. But, I am worried that the relays will introduce some Hum into the system. Any suggestions would be appreciated!!

Thanks
Tristan
 

I haven't used the 15/70 DTS system, so I don't feel qualified to answer that question.

 

Another imax question. On our old projector (relay based) the rotor air pressure gauge reads 0 psi when the projector is running, but when the dowser is opened, then the pressure jumps up to the normal 60psi. My question is: is this normal for this era of projector, and, would running the projector with the dowser closed damage the film?

Thanks
Tristan
 

There is a definate change in sound when the dowser is closed. And there is noticeable marring on the film after the credits, because the dowser is closed at that point. The dowser button on the projector console is not functioning at this point in time, instead we are using the "Dowser Test" toggle on the back of the lamphouse. The problem is supposed to be fixed at next service. I hate to say it but the projector is very problematic. There are a few problems that I have experienced that make starting a show a very nerve-racking time. For instance:
Sometimes at show startup the dowswer will somehow open itself, thus showing Acad. leader on the screen. The only way to shut the dowser is to flip the toggle switch up and then down again. At that point the lamp shuts off for some strange reason. So that causes the need to re-strike the lamp.

And- sometimes in the morning when things are just getting turned on, The "system on" button does not work. It does nothing. The solution is this: I open the MKII reel unit, turn the local disconnect switch off in the bottom the reel unit, and then remove the positive battery cable in the top of the reel unit. I wait a few seconds, replace the terminal, switch the reel unit on via the local disconnect knob, and hope for the best. Usually it takes a repeat of 10 times to get the system to power up. The IMAX techs are stumped by the problem.
I suspect that it is in the E-Stop system somewhere.

Going from SR projectors to the mammoth old beast is a hard change to deal with. Maybe I should quit whining and just deal with it

Let me know if you know of any solutions to the problems
Thx- Tristan
 

My boss must have been blowing smoke, but if you go to BMZ the only print listed is the one at Spokane.
"Man Belongs to Earth" was the premier show for Expo '74 wasn't it??

Tristan

P.S. The question isn't "What Prints does the Ontario Cinesphere have?" The real question is "What prints does the Ontario Cinesphere not have?" I have seen those picures of your film library- very impressive!
 

Tristan - have you tried a good swift kick?

 

Who is your regular IMAX tech? Have you spoken to them about the air pressure oddities?

Since having the SR 's installed here 3 years ago some of the niceties of what air pressure gauges did what when on ole system 34 have fled from my brain. Be thankful you have an external pressure gauge. There are none on SR projectors.
We had a problem 2 years back when the rotor pressure dropped and film got scratched.No alarm. The only air pressure alarm is on the main supply.

We have spoken to the Tech about all the problems listed. The rotor air gauge situation does not seem to be a big concern to him. I am hoping that the problems can be fixed on the next service call.

The SR projectors are equipped with a Rotor air pressure gauge. It is located beneath the projector cover on the left hand side of the projector. Why they decided to put the gauge out of view of the operator is beyond me. I have seen a "Rotor air pressure low" alarm on the system in Boise. The system was installed in '99. I can't imagine that there is an SR projector out there that does not have some sort of warning device to alert the operator of low rotor pressure. Everyone is familiar with the usual beep-beep of the "Air Pressure low" alert that is displayed when the air tank is drained at night. That system will even warn you if you lose 1 of the 3 phases of power supplied to the rectifiers.

-Tristan
 

quote:

---

Fantasia 2000, Beauty and the Beast, Treasure Planet, Lion King, and (likely) Aladdin are all "letterboxed" as 1.66 on the 1.4 Imax screen. Apollo 13 will probably follow suit.

Apollo will probably be edited to a certain extent, both for content and length (print cost). 140 minutes X 330 ft/min X .66 $/ft = $30,492 per print.

It would also weigh in at about 900 pounds. My forklift will pick up 1,000 pounds, but you won't see me trying it anytime soon!

There are several modifications for the QTRU reel unit: original configuration will hold about 60 minutes on a reel; for $20,000, the "Fantasia" upgrade will hold about 90 minutes on a reel using the bottom two reel arms; and for another $20,000, the "Apollo" upgrade will hold about 120 minutes on a reel using the bottom two reel arms and 90 minutes on the middle two reel arms with the top arm holding about 60.

The MK2 reel unit with 60-inch reels can hold 90 minutes of film.

The SR projectors are capable of doing a single changeover during a show. A multiple changeover version of the software has been promised, but I don't think it has become anything of a reality yet. That means that an SR with an unmodified QT can run 120 minutes without interruption, or 300 minutes with a full blown QT package. When it comes to feature-length 3D films, both projectors run simultaneously, so no changeover is possible.

The GT and Classic are single-projector systems and, obviously, cannot do a changeover without a second projector. They are limited by their reel unit.

There is also a question of sound system capacity. Theaters with dubbers have to upgrade to a digital playback source at some point. Only so much 35mm fullcoat will fit on a reel.

With all that said, Waikiki Imax is a GT 3D system (probably with a QTRU and a MK2). Polynesian opened in 1991 and is 2D only, so my guess is that it is a Classic with a MK1. The Bishop Museum will have an SR dome and a QTRU when it opens in 2004.

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