Film-Tech Forum ARCHIVE: IMAX GT projector questions

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Posted by Stewart Anderson (Member # 1809) on 04-24-2004, 12:34 AM:

How do you thread the lower rotor? Are the lower and upper rotors separate? How are the field flatter(s) arranged. One lamp or two? Anyone have good pics of a IMAX GT projector (up close to the front of the projector with the hood open)?

Any other interesting info...

Posted by Fabrice Dubourg (Member # 1635) on 04-24-2004, 04:06 AM:

have a look here :

http://www.film-tech.com/pics/imet/imet.html

imax gt

Posted by Steven Privett (Member # 718) on 04-24-2004, 12:47 PM:

c'mon, rip those covers off. We want pictures.

Posted by Robert Stawiarski (Member # 1842) on 04-24-2004, 01:12 PM:

Providing detailed front end pictures or threading instructions is not allowed. As for a couple of your questions... There is one large rotor on the 3D GT with separate segments for left (lower section of the rotor) and right eye (upper section of the rotor), and film rails separate these sections. The 3D GT uses two 15 kW water and air-cooled xenon lamps. The water flows through the anode and cathode of the lamps.

The film rests on registration pins on both sides of the field flattener and the film is held in place against the field lens by a vacuum while the image is projected. The field lens has two separate glass surfaces, each slightly more than twice the width of 15/70 film. This is so that when the field lens is cycled (moved up/down), the film rests against a clean surface. There are four wiper bars in a 3D setup which help to keep the field lens clean.

[ 04-24-2004, 04:53 PM: Message edited by: Robert Stawiarski ]

Posted by Stewart Anderson (Member # 1809) on 04-24-2004, 02:54 PM:

It seems that there would be a lot of stuff in the way when you thread the lower rotor. Do you have to remove the field flattener(s)?

Posted by Robert Stawiarski (Member # 1842) on 04-24-2004, 03:09 PM:

The field flattener has to be in when threading, but is cleaned between shows. It is somewhat cramped when threading left-eye, but like with anything else, it isn't too bad once you get used to it. The operator just has to be careful to not let his hands or fingers touch the field lens when threading because the oil can be visible on screen.

Posted by Brian Michael Weidemann (Member # 2243) on 04-24-2004, 09:19 PM:

During threading the whole aperture block, into which the field-flattener slides, is pulled back. A perfectly cleaned field flattener is put in place, and the block is closed (at that particular stage in threading). Separators also pull back so that film can slide down to lower deck on input and output sides, and then they're closed for upper deck threading. As stated, both decks utilize the same rotor, with slightly offset rail segments from one deck to the next.

On GT's with a shutter installed, there's less working room. Ours has no shutters, so there seems to be plenty of space to work the film in ... of course, it's all skill, baby! [Razz]

Posted by Ben Stephenson (Member # 741) on 07-07-2004, 10:58 AM:

GT projector must save time, You only have one projector to lace. I understand there's the same amount of film but you lace both eye's at the some time (well one just after the other).

Posted by Dick Vaughan (Member # 540) on 07-08-2004, 02:43 AM:

If you are running 2D/3D or 2D/2D back to back then SR projectors give you the advantage of lacing one projector while the other is running. E.G if we are running a 2D show on the right projector then we can lace the left eye of the following 3D show on the other projector.

Posted by Gordon McLeod (Member # 33) on 07-08-2004, 09:12 AM:

Better than 2 SR projectors are two 15K classics [Big Grin]

Posted by Dick Vaughan (Member # 540) on 07-08-2004, 09:21 AM:

Well Gord I can't say I wasn't envious when I was in Quebec.
2 classics,2 Mk1 reel units and a QTRU! Buggerbitch!

Posted by Gordon McLeod (Member # 33) on 07-08-2004, 03:53 PM:

But look at it this way they don't have cinerama and a dp70 so you make up for it

Posted by Mark Gulbrandsen (Member # 72) on 07-12-2004, 07:53 PM:

"Providing detailed front end pictures or threading instructions is not allowed"

Bwahahahahahahahahah!!!!!! Thats hilarious! Not allowed... how could they stop anyone? Anyone can read the many patents which describe in detail and dimensions how it works and is built and anyone can visit the patent office and look in detail at the working model.

I have so very many detailed shots of Imax equipemt that I couldn't even count em all.....

Mark

Posted by Richard Hamilton (Member # 321) on 07-12-2004, 11:22 PM:

Mark,
I was installing a sound system at the ScottishPower Space Theatre in Glasgow Scotland and asked if I could tour the Imax booth there. The director of the place took me to the booth and showed me around, but told the projectionist after the show NOT to open the projector. I wasn't allowed to see how it was threaded or operated, because I am the competition! He was serious, because he said the patent was either expired, or almost expired, and he thought we would copy it.

Rick

Posted by Robert Stawiarski (Member # 1842) on 07-12-2004, 11:39 PM:

Mark, just passing along the information that was passed along to me. Notice that none of the IMAX booth tour photos, both here and Cinematour, have close front-end pictures like the 35mm booth tours. Do you think that is by coincidence? The manual is confidential, and would never be allowed posted like the manuals are for other equipment on this site. From what I have heard, some projection managers and techs have to sign NDAs, which is not exactly commonplace in the 35mm world. Sure, you might be able to go down to the patent office like you say, but nevertheless, rules are rules.

As Adam Martin has noticed previously, some of your posts about IMAX have a bit of negative tone to them. There is a reason why IMAX does the things that they do. I think Stewart best sums it up in his posts about his CDC system (a theatre you service?):

"I could go over all the problems that we have had with our system as a result of going with a cheaper brand..." or "They are a bit cheaper then IMAX, but you get what you pay for in my opinion."

I'm not laughing.

Posted by Mark Gulbrandsen (Member # 72) on 07-13-2004, 08:49 AM:

"I could go over all the problems that we have had with our system as a result of going with a cheaper brand..." or "They are a bit cheaper then IMAX, but you get what you pay for in my opinion."

Of course that is the opinion of a very inexperienced person. Actually the problems there are the result of hiring people, including management, that know nothing about what they have there and paying them little for what they do. Smart management would have installed the system completely as CDC reccomended but they didn't. I think Phil can speak with experience on these people as he spec'd the original 8/70 system they had there. I'd wager any day that the CDC system to be as good as the standard Imax projecton system. In fact from its first print the Zion Cayon CDC projector did get 2000 runs, then they had the film cleaned and Photogaurded and got another 2000 runs or so till the color faded... plus not one missed show, so obviously the projector is quite reliable and gentle on film. CDC now uses that print as a test film at its shop. The difference at Zion Canyon is that they have an experienced 15/70 projection staff and good management. How well and reliably a site of this type runs reflects much more on the management decisions and the experience of the hired operating personel. In the case of Stewarts location its beyond dismal with even management not having a clue about how it should be run. Here they have learned from the mistakes thay've made(ouch!). Most of their problems stemmed from not having a UPS supply for the system and being in a very, very bad power location. CDC originally reccomended that it be installed. The problems did not stem from it being a cheaper system because its not a cheaper system. At Stews location there are no operators there with any previous 15/70 experience at all, including the "Head Projectionist". Sorry but in my book ya don't get to be head projectionist with only a few months experience, but there last month ya could have been sweeping floors and next month ya can be head projectionist [Eek!]

!

I only maintain the sound system there, CDC maintains the projectors unless they request me to do so and I have made one repair to one machine. Since I revamped much of the original Iwerks sound system it has had zero problems at all for the better part of a year now.

Sorry but I am still laughing because there is a system that is just as good as Imax's. If you were to buy a CDC system tommrrow I doubt that you'd find it cheap at all. It would cost a comparable price of an equivelent Imax system could you purchase it, and you'd find that CDC's build quality, including the optics, to be every bit as good in every aspect and perhaps better in some.

As for Imax I much admire the technology and build quality of their systems. The only thing I dislike is the very inferior SR system and all the royalties one is paying to them. So for clarification that is what I am negative about. Even the El-Paso Dome theatre pulled Imax out and installed a CDC system because of the obscene Imax expenses. Other locations have also pulled it out and put in Kinoton and Mega 8/70 as Richard will testify to. Oddly, El Paso too have had zero problems with their CDC system as has St. Louis, OKC, Kansas City and all the others that have been installed. The only real problem location is here and is due to extremely dismal management decisions.

Mark

Posted by Adam Martin (Member # 641) on 07-13-2004, 09:33 AM:

For the most part, the patents that the general public can freely see online, etc., are just working models of the concepts that Imax has implemented in their equipment. These concepts have been fine tuned to the point that they no longer specifically resemble the drawings in the patent documents, and you would be hard pressed to find an exact match in the equipment turned out at Imax's manufacturing facility.

That's why Imax doesn't allow examination/dissemination ... they must allow you (in the patent documentation) to see the concept that everything is based upon, but they don't want you to know exactly how they perfected and implemented it.

How can they enforce it? Simple. It's in the equipment contract. You breach the contract and you can be held liable.

Posted by Mark Gulbrandsen (Member # 72) on 07-13-2004, 01:24 PM:

Of course I don't have a contract with Imax nor were there any signs posted on the premises disallowing anyone to take photographs. Many Imax customers have also given alot of thought before signing again and many have not and let the equipment be removed. The pictures I have were taken in a shuttered Edwards Imax in which the SR Equipment came close to ending up in the Dumpster. The property owner was considering conversion to 8/70 and keep the theatre operating or tear down the building and build something else there. It sat for way over a year. The cost to convert it to other than film use exceeded the original cost of the building itself and both Edwards and Imax had apparently abandoned the equipment and the property owner couldn't get a straight answer one way or the other. Imax of course rescued the location, mainly to save face for now, but there was never any profit to make at that location so we'll see how long that lasts.

As for patents it all depends on how unique it is weather the patent office requies a working model or not. In some cases providing a working model of somethng that is made to run correctly by fiddling with it after the fact is the only way a patent can be fully protected. If a certain aspect like that is also not patented then that aspect could also be patented by someone else. If Imax is dumb enough to expose that sort of stuff without fully patenting it that is plain stupid. All one had to do is apply for it and you are protected while the patent is cleared or not. Anyone can gain access to any booth if one wants to spy badly enough. Fortunately the smallish LF market itself pretty much eliminates that in itself.

Steve K can speak of his experience at Cesars Palace when he tried to take a photo of the booth there. He was hauled off to security and his camera was almost confiscated. I thought it hilarious and thought to myself about how many had taken a photo of that booth and went undetected. We thought they just didn't want to expose just how bad the theatre really was.

Mark

[ 07-13-2004, 07:50 PM: Message edited by: Mark Gulbrandsen ]

Posted by Steve Kraus (Member # 476) on 07-14-2004, 01:35 AM:

Mark exaggerates. No one was hauled off to security or anywhere else. Just an argument with a tourguide-wench who could not explain her assertion that photography--even without flash--was going to harm the delicate equipment.

Posted by Stewart Anderson (Member # 1809) on 07-14-2004, 01:44 AM:

quote:
At Stews location there are no operators there with any previous 15/70 experience at all, including the "Head Projectionist". Sorry but in my book ya don't get to be head projectionist with only a few months experience, but there last month ya could have been sweeping floors and next month ya can be head projectionist !

That hurts, AND ITS NOT TRUE!!!!!!

I think that 4 1/2 years of 35mm with 2 years of 8/70 should have been enough to venture in to the world of 15/70. Now, as for being the head projectionist with not enough experience, well I now have 5 years under my belt with 2 years 8/70 and now 1 1 /2 years 15/70...WTF [Mad]

And as for knowing the equipment, I have sometimes proven our own techs (the people who built this machine) wrong on occasion! I have always had a very strong passion for this line of work and hence I have learned it very fast and have been learning it for a long time. I don't appreciate techs assuming that I don't know what I'm doing because I'm young [Mad]

Posted by Mark Gulbrandsen (Member # 72) on 07-14-2004, 04:45 AM:

Stewart,
I don't assume that, I've seen that. I won't bring up what happened across the way a short time ago with the 35mm format. 8/70 and 35mm experience just does not count in my book towards 15/70 experience, the only similarity there is the material the film is made out of. 15/70 is an entirely different world in itself and requires an entirely different frame of mind from the normal 35mm and 70mm formats to really be able to work with it. And that different frame of mind must also encompass management, not just the operators. Keep in mind that many very experienced 15/70 operators have never had a days worth of 35mm experience ever.

None of the other locations generally have any real projector problems at all, just audio problems with their dubbers, IED equipment, or P8 players (as you did) because some are getting very old. I think getting 4000 runs from a 15/70 print itself speaks quite highly of the projector and platter system. BTW: Age has nothing to do with it!!

Mark

Posted by Richard Hamilton (Member # 321) on 07-14-2004, 04:59 AM:

I think I have had better luck training people with NO 35mm experience on how to run a large format machine. We always have it written in our contracts that the customer has to have an experienced projectionist for me to train, but that is rarely the case overseas. When there is a language barrier, it seems easier to train someone with no experience in film rather than someone who is already set in their ways, and speaks no or little english.

Rick

Posted by Stewart Anderson (Member # 1809) on 07-14-2004, 06:51 AM:

Mark,

I didn't say that 35mm or 870 did count for 1570 experience, what I did say is that it is a good way to start. I became the chief projectionist based on my knowledge of the equipment that I have proven to the museum AND CDC time and time again. If anyone that knows me cares to challenge this PLEASE DO! I have worked with some of the best projectionists in Utah and they can back this. As for the recent 35mm incident, that originated with a AUTOMATION PROBLEM [Wink]

and faulty gate band assembly that caused me to panic and so yes I did make a mistake, however people make mistakes even "experienced projectionists", especially when under a state of sudden panic caused by EQUIPMENT FAILURE.

As for the projector in Zions...How long did it spend in a warehouse before it was installed? How many bugs did CDC have to work out of it and how long did they take? And are they STILL working out the bugs? Did they have a UPS? Was it always functioning properly? Our 1570 originated from some very unfortunate beginnings AND I WILL NOT BE THE CONVENIENT BLAME FOR PROBLEMS ANY MORE! And yes, a sensitive nerve has been struck...

[ 07-14-2004, 08:11 AM: Message edited by: Stewart Anderson ]

Posted by Richard Fowler (Member # 893) on 07-14-2004, 08:50 AM:

Every brand will have problems due to the almost hand built nature of the beast for this very tiny market. I have a close friend who is a IMAX tech and his stories of problems and his experience in solving them mirror some that I have encountered with other brands. Our nerves are long passed the "Panic" stage and into what are the options mode [Big Grin]

Posted by Mark Gulbrandsen (Member # 72) on 07-23-2004, 08:35 PM:

Actually I don't think anyone that has a tendency to panic should be in a position such as operating 15/70. In fact a simple panic test is probably the first thing I'd give to perspective candidates. As I said you need to posess a certain state of mind to be able run this stuff and stay out of trouble, you also need a predeveloped instinct for it. Pretty much the same as any professional pilot. In fact the only option in this buisness is not to panic when something goes amuck. Keeping your cool is far more beneficial to all.

Mark

Posted by Stewart Anderson (Member # 1809) on 07-26-2004, 12:07 AM:

Perhaps 'panic' was a bad choice of words. Maybe I should have just said that in that situation I had about 1/8th of a second to make a decision with many different variables to think about. Also, if anyone in this forum 'Mark' [Wink]

is PERFECT, please let yourself be known.
I have actually been in many of these situations I have described above and everyone here should know that people only hear about the stuff we do wrong. Now Mark, if you want to continue to persecute me for this ONE mistake, and also probably the ONLY mistake you have heard of that I have made, then that is your call. But keep in mind the only things you hear is the bad. And you have no idea what our day to day operations are like because you are only around for a few hours per 1/2 year. If you think I don't know what I'm doing talk to ANYONE that has worked with me directly (that includes Jordan Commons). Hell, talk to Abass or Hamid!

[ 07-29-2004, 02:16 PM: Message edited by: Stewart Anderson ]