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You were in the Indianapolis IMAX 3-D, where Gary Weyers is the chief projectionist...by far the strictist and cleanest booth in the land...out of his own pocket he pays for the fly paper walk in pad that gets changed every day, as well as disposable booties for those that don't have their own "booth shoes."

He has PTR rollers on either side of the rotor (sticky going into the rotor, less sticky on the output side). The PTRs are all changed for EACH showing.

As to the "reel-units"...he has two MarkIIs with 60" decks, 4-decks per reel-unit. What you may not have noticed is the two roller trees between the projector and the reel units so the film may start on either reel unit and end up on either reel unit. For 3-D features, both "eyes'" films are going in the same direction though logistically they may not start nor end up on the same reel unit. As you face the screen, both strips of film feed from the right. The whole system is in triangular formation.

As to Film-Guard on IMAX...I wouldn't do it...it will for sure slime up the field flattener. We have supplied the Inidanpolis IMAX-3D with Film-Guard for their conventional 35/70 system. Incidentally, they use 7000 watts on 35mm with no problems. But don't try this at home! ;-)

Steve

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Gary's booth never seems to age...he keeps it spotless!

Steve

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I hadn't thought about the field flattner when considering my first post. It would definately cause all kinds of problems there no matter where the cleaner was mounted, or how smooth the Film Guard was on the print.

Like Gordon, I also have very little trouble with dirt. One or two Field flattner changes per show is all that is ever needed on a regularly run print. New prints are a little dirtier, but after a few days have no problems.

BTW, Gordon, what do you use on your Field Flattners up in Canada? I use a product called Dry Wash 'N Guard, that was reccomended by the projector manufacturer.

Putting a thin film of oil or other material between two very smooth surfaces (the field lens and the film) acts like a "glue" on a molecular basis, and would cause them to stick together. So trying to change/clean the field flattener while the treated film is running could jerk the film out of position, causing a jam.

To illustrate, take two plates of glass and put a drop of oil between them. When the oil spreads out, it will cause the glass plates to stick to each other, not slip.

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For sound they had 35mm mag film running in conjunction with a digital version on a disc, somewhat similar to DTS, but without the timecode. The sound is synchronised with the picture through the automation system. The film needs to be threaded in an exact spot and then the sound and picture start at the same time (has anyone seen Singing in the Rain?).

If the film breaks, the same piece of Mag sound must be removed and the disc be edited through the Automation.

Similarly, if one of the 3D prints has film removed, it must either be replaced with black spacer or the same amount removed from the other print, otherwise the two prints end up out of sync with each other and the 3d effect can be lost.

I was interested to hear that there is no racking control on the projector, and due to the sound no being part of the film, if you start up out of frame, you loose the session, as there is no way to change the framing, and by stopping the projector to fix it you loose your sound link.

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Ethan, if you weren't seeing the film in 3-D, there could be two causes. The LCD shutters on your headpiece might not have been working properly, or you could have ambliopia,(sp?) sometimes called lazy eye.

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Also a cause can be strabismus (cross-eyedness). Amblyopia & strabismus can & usually are caught in routine eye exams. Or...it may turn out that you're just not "wired" for stereo. Those neural pathways are developed in infancy & early childhood. If they don't, it's one eye: flat; two eyes: scope. Or the favorite of focusing near & far simultaneously for max depth of field. Or "alternating use": stereoblind folk rarely have the "tired eyes" feeling.

A stereo vision test is often not the usual part of an eye exam, but if you go to one of the monolithic chain vision centers (Opti-World, etc), they have monolithic standardized tests to check for EVERYTHING (like the military). So don't be shocked if Opti-World checks both your stereo vision & prostate.

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A lot of people have amblyopia and get 3-D visual cues from focus, or by shifting head positions. For them, any 2-D movie looks 3-D.

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Those are "monocular depth cues", & included are relative size & changes in relative position in the field of vision. I am stereoblind, & did not know until I was 35 & idly took a stereo vision exam to kill some time! Monocular depth cues are so successful that I apparently used them to pass those old "miniature in the box" 3D exams for driver licenses. And used them for SCCA rallying & who knows what else for 35 years.

For the stereoblind 2D movies still look like flat 2D & not at all like the spatial arrangement of the rest of the world, since fewer monocular cues will work on a 2D movie; & most importantly, the automatic mental processing of the interaction & differences in the monocular cues tosses the movie out as non-real when the results are aberrant. Apparent size cues OK but items apparently at different distances do not respond correctly to focus changes? Toss it out.

3D movies look like 2D movies, only dimmer.

The 3D effect "works" on the Stereo People only because it mimics their stereo cues of convergence. The Stereo People also use monocular cues, but it seems that in their perceptual development they've assigned such an outsize importance to convergence that those binocular cues are enough for the 3D Movie Experience.

Glad I found this out before I was ever asked to run a 3D movie!

"The people in the audience are screaming & throwing up! What's wrong with the movie?"

"Hmm, looks fine to me..."

It's estimated that *at least* 10% of the population is stereoblind, and that number could be *very* low because many who are stereoblind do not know it. So about 10% of the folks in each 3D movie are wasting their money! Everybody should get checked for stereoblindness, though. Especially kids: they check them for colorblindness, they oughta check them for stereoblindness before sending them out to get beaned by baseballs!