How an IMAX projector works

I’m worn out by the Charlottesville business, and depressed that some readers are calling for speech bans. We won’t discuss that in this thread (there are other posts where you can do that). Instead, let’s learn how an IMAX projector works. I’ve been to a few IMAX movies, the first being “Flying” or “Flight” (can’t remember the name [a reader below says it’s “To Fly”]) at the Smithsonian. They’re stunning, and until I saw this video I had no idea that a.) they involve real film stock (70 mm) and b.) they’re bloody COMPLICATED! I found this fascinating and offer it as an afternoon respite:


  1. Posted August 14, 2017 at 3:24 pm | Permalink

    I believe the movie was called “To Fly” and one of the things I loved about it was the soundtrack, which had Pachelbel’s Canon in D major.

  2. Liz
    Posted August 14, 2017 at 3:49 pm | Permalink

    I’ve seen many movies/documentaries in the IMAX theatres at the Liberty Science Center in NJ and the Museum of Science in Boston. The best seats are right on top of the projector.

  3. Ken Kukec
    Posted August 14, 2017 at 3:56 pm | Permalink

    Dang, wish I knew you could be “paid for diddling” afore I made certain career choices.

    • rickflick
      Posted August 14, 2017 at 4:18 pm | Permalink

      You could probably diddle in retirement. Lot’s to look forward to. 😎

  4. bonetired
    Posted August 14, 2017 at 3:57 pm | Permalink

    I actually saw “Dunkirk” at my local IMAX cinema and, being the first time that I had seen a movie in one, I was astonished at the quality of the picture. Just blown away.

    ( As an aside, it is quite possible that my late father-in-law gave the order to fire the last shells fired by the British army at Dunkirk!)

    • Randy schenck
      Posted August 14, 2017 at 4:16 pm | Permalink

      Wow, did he get out?

      • bonetired
        Posted August 14, 2017 at 4:25 pm | Permalink

        He did indeed. Apparently it was in a coal barge that was being used to evacuate the troops. His sergeant had “procured” a bottle of whisky and they shared it as they came across the Channel!

        • Randy schenck
          Posted August 14, 2017 at 4:35 pm | Permalink


  5. Geoff Toscano
    Posted August 14, 2017 at 4:00 pm | Permalink

    I started a monthly cinema ticket years ago, but find I don’t get my money’s worth these days. Yet somehow getting round to cancelling direct debits never occurs to me.

    Net result is I do get to see some good films (and some awful ones), and saw Dunkirk on its day of release in the UK. I had no idea that projection is so fearfully complicated.

  6. Stephen Barnard
    Posted August 14, 2017 at 4:26 pm | Permalink

    Fascinating video, but 70mm is a dying technology for several reasons, as should be obvious from the expensive, cumbersome, and delicate equipment, not to mention the nearly obsolete film medium. In the near future IMAX will be a museum piece.

    • rickflick
      Posted August 14, 2017 at 4:36 pm | Permalink

      I hope the end effect can be obtained with a digital projector technology of some kind. I remember a documentary showing an IMAX camera being used underwater for a film and the size and awkwardness of it was noticeable.
      The camera has been use in space as well – I think on the space station.

      • Posted August 14, 2017 at 5:23 pm | Permalink

        I think the most astonishing use of IMAX was the 1998 Everest film. How do you survive the mountain AND take film at the same time?!

        • gravelinspector-Aidan
          Posted August 14, 2017 at 6:48 pm | Permalink

          By being a bloody good mountaineer first, and a pretty good cameraman second.

    • Randy schenck
      Posted August 14, 2017 at 4:39 pm | Permalink

      I would guess as much. Everything is digital these days and the logistics of flying film all over the country is nuts. I remember what it was like doing it for the military theaters and they are all over the world.

    • Michael Fisher
      Posted August 14, 2017 at 5:32 pm | Permalink

      IMAX is a brand, it’s not tied to the use of 70mm film stock.

      Nearly all [or all?] 70mm films have a stage where they are converted from film to ‘digital intermediate’ & then back to film again! The digital intermediate stage is for editing [colour grading, brightness, contrast, grain reduction & digital effects].

      Not one movie-length production has ever been filmed entirely in 70mm film – the cameras for such film recording are ridiculouly heavy, cumbersome & noisy. This means it’s difficult [or impossible] to record simultaneous sound, thus dialogue etc is often a separate job & I would suppose you need a foley artist team at the top of there game with coconut halves at the ready. Nearly all films in the IMAX brand are 35 mm films scaled up to the IMAX format [with a digital intermediate stage too of course] such as re-releases of 35 mm films like Jurassic Park.

      These things I’ve read, but don’t know to be absolutely true:

      ** IMAX is moving to dual laser projectors [dual to enable 3D when required] fed from a HDD medium – thus by definition digital
      ** Digital IMAX isn’t up to the projection resolution of 70 mm film, but they’re fairly close using digital trickery I don’t understand that fools the eye/brain. Such as compression & decompression of digital files, but only having really high res where it matters such as fast moving parts of the image & bits that humans focus on such as faces.

      This bit could well be rubbish:

      ** The bottleneck is a light, small, hi-res digital, wide angle recording camera that doesn’t need mega-bright lighting rigs to work right. I assume this is difficult to achieve, especially at the new 60 fps 4k res standard.
      ** But possibly a non-problem since CGI is so clever now that sub-standard material can be upscale interpolated well enough to fool us the viewers.

      • Stephen Barnard
        Posted August 14, 2017 at 6:59 pm | Permalink

        ** The bottleneck is a light, small, hi-res digital, wide angle recording camera that doesn’t need mega-bright lighting rigs to work right. I assume this is difficult to achieve, especially at the new 60 fps 4k res standard.


        ** But possibly a non-problem since CGI is so clever now that sub-standard material can be upscale interpolated well enough to fool us the viewers.


        • Michael Fisher
          Posted August 14, 2017 at 7:13 pm | Permalink

          LOL Thanks Stephen – I’m glad you confirmed what I thought
          A bit of ‘why’ from you would have been of benefit to me

          • Stephen Barnard
            Posted August 14, 2017 at 7:38 pm | Permalink

            For one thing, the tiny, cheap camera on my drone takes excellent wide-angle 4K video, and I use a 4-stop neutral density filter in normal daylight. My consumer-grade Panasonic G4 takes excellent 4K video. I can’t believe that a digital sensor far surpassing 70mm film in resolution and sensitivity isn’t technically feasible. What are we using in observatories?

            Regarding CGI, it will get more and more realistic if it ever gets past the uncanny valley, but it won’t change a sow’s ear into a silk purse.

            • Michael Fisher
              Posted August 14, 2017 at 8:05 pm | Permalink

              It might be the 3D aspect of IMAX, I dunno
              As of 3 years ago an IMAX 3D 4k digital camera weighed 38 lb. Pics etc here:

              I’m with you on the unhappy valley thing, but it doesn’t have to be

              Sow’s ear to silk purse is something that can happen in film & audio – the interpolation required to ‘fill in’ the extra pixels of low res to hi res has been advancing for a long time & is most successful with textures. But faces, bodies in motion etc is advancing yearly. We will have the old, scratchy Alan Ladd & Jimmy Stewart movies rendered to large format, hi res one day. Licensing these classic actors images, in the broad sense of appearance, mannerisms, audio, is going to be a big thing – appearing in new movies & entirely lost old movies regenerated.

  7. rickflick
    Posted August 14, 2017 at 4:33 pm | Permalink

    I’ve seen a handful of IMAX shows and it’s very enjoyable. I had one experience that was a bit shocking. The program was about the undersea world and the coral reef. The show started with a submarine view of a large school of reef fish swirling around in a kind of 3D effect. It was astonishing, as if you were diving surrounded by thousands of colorful fishes. Instantly a few young people – teens and early 20s – seated in front of us began screaming. They stood up in a panic, and I could tell it was a small group of people with mental disabilities. The shrieks were animalistic and blood-curdling. Their caregivers directed them out of the theater.
    The event puzzled me at the time and since. I wonder what kind of disability was it that would terrify these people. What was the neuroanatomy? How did the caregivers not know the limits of toleration of their charges? How did my excitement and enjoyment at seeing a film with disorienting beauty translate into terror for these people? I guess I’ll never know.

    • Michael Fisher
      Posted August 14, 2017 at 6:17 pm | Permalink

      I took my neighbour Betty [1917 – 2014] to the National Sea Life Centre, Birmingham, UK for her 95th B. She loved otter feeding time, octopuses, seahorses & the sharks [particularly the rays] & then the ‘4D cinema experience’ that they host, which isn’t quite IMAX standard, but still very immersive [all ones vision is taken up by the screen] & surround soundy.

      She wanted to get out after 3 minutes because she couldn’t adapt to being so deeply immersed & found the experience nauseating. We discussed it later & her main problem was the surround sound which was very ‘wide’ with marine life whooshing overhead & also around the back. The bass was also seriously overdone – one could feel it in the chest, ridiculous & unpleasant.

      She hadn’t been to the cinema for thirty years, but she remembered wide screen films, such as 2.66:1 with appreciation [Oklahoma, Seven Brides…, Lady & the Tramp], but in that era the sound separation was civilised – not you Dark Side Of The Moon acid trip! One could enjoy ones Kia-Ora & ice creams unmolested by whirling dervishes overhead.

      I speculate that might be the problem. Plus a touch of mass hysteria among a close-knit, impressionable group a la O Milagre do Sol @ Fátima in 1917

      • gravelinspector-Aidan
        Posted August 14, 2017 at 6:58 pm | Permalink

        I must admit that the only time I’ve seen an IMAX (the space+3d one, in the London IMAX, about 2008), I found it nauseating as well. Despite a stomach well hardened to rolling in escape trainers and vertigo from trapped air while diving, it was really unpleasant to sit through. I tried a non-IMAX 3d film a few years later and had no more than a thumping headache after a few minutes, so I’m not sure if it was the screen scale, or the 3d effects.
        There’s now a cinema within under 2 hours travel, which boasts IMAX capability. Haven’t seen any advert sufficient to tempt me in yet.

        • Michael Fisher
          Posted August 14, 2017 at 7:34 pm | Permalink

          Yes. I’m not tempted by the experience either – not joyful. Outside of documentaries the material is aimed at people who are not me [bang, bang. Squeal of tyres. Smash. Screams – type audience]. As a book reader I don’t need to be fed on all inputs for entertainment. Additionally I hate the rustlers of crisp packets & the hordes of phone addicts. Grumble, grumble.

          • gravelinspector-Aidan
            Posted August 20, 2017 at 7:48 am | Permalink

            [bang, bang. Squeal of tyres. Smash. Screams – type audience].

            Them. Yeah, I saw an advert outside the cinema for “Terminator [several] – 3D” and was instantly tempted to not go in. I do notice what’s on the advert board now that I walk past it, but I still haven’t been in except to use the toilets.

    • Michael Fisher
      Posted August 14, 2017 at 6:52 pm | Permalink

      Also some of them probably had hearing disabilities. IMAX pushes out a LOT of sound energy over a very wide range of intensities/frequencies – hearing aids can’t cope with this & nearly all hearing aid users don’t know how to adjust their aids in real time [or at all]. A painful experience.

      I found a report that a quarter of people with hearing aids stop wearing them, but in the elderly group I know it’s more than half. Fiddly, horrible things with tiny batteries. Apple, or someone, could make a 2nd fortune in that arena – starting with wi-fi re-charging if they can figure out a tiny format for that.

      • gravelinspector-Aidan
        Posted August 14, 2017 at 7:02 pm | Permalink

        Quoth Scotty (shortly before changing the laws of physics), “Ye canna change the laws of physics!”
        wireless transmission of energy requires magnetic field strength, cross sectional area of the receiver coil (I leave the transmitter and efficiency as problems for the base-station designer) and current-turns. Which doesn’t add up to “compact”.

        • Michael Fisher
          Posted August 14, 2017 at 7:22 pm | Permalink

          Yeah I know [more or less]. There would have to be some sort of large area aerial thingy that auto-deploys from the hearing aid & squishes away when not needed. Or dispense with wi-fi & have a pair of human ear shapes on a stand you plug your aids into? A bit Dali don’t you think?

          • rickflick
            Posted August 14, 2017 at 8:36 pm | Permalink

            Put the ear next to the melting clock and I think we’re in business.
            BTW, US lawmakers are trying to legislate to allow easier access to hearing aids. Cheaper too. I worry that half their effort will be thrown in the trash, but, who knows it might improve the lives of many.

            • Michael Fisher
              Posted August 14, 2017 at 9:09 pm | Permalink

              Dali’s wacky crucified Christ, but with huge ears, for the deaf Christian demographic?

              Let’s hope so! Although first – design improvements would expand usage & drive prices down to where it’s needed. Say from $500 down to $80. Same with mobile phones for the oldsters – too expensive & badly designed today.

              In Britain we have matinee, off peak cinema showings for the deaf of all the main films [subtitles & hands signing] & I think most cinemas have the ‘induction loop’ system that communicates audio to hearing aids. All the big stores & banks near me have it too at the till so the deaf can hear the sales person [who speaks into a mic]. Public payphones have it.

              It is a vastly underused system because of the crap design of hearing aids – the user has to switch manually to induction loop reception.

              • rickflick
                Posted August 14, 2017 at 9:43 pm | Permalink

                I’ve never heard of those hearing technologies, but it sounds quite promising somewhere down the road to our (Utopian) future. Personally, I’m looking forward to the day I can trade in my 70 year old bod for a whole suite of new parts. I just can’t wait to get a new lumbar region, plus a spanking new frontal lobe.

  8. davidintoronto
    Posted August 14, 2017 at 4:56 pm | Permalink

    IMAX also has a proprietary digital projection system. Unfortunately, advertising doesn’t always distinguish between digital IMAX (sometimes referred to as “LieMAX” ;)) and 70mm/15perf celluloid IMAX (as seen in the Youtube video). If you have a choice, always pick the latter.

  9. ploubere
    Posted August 14, 2017 at 5:29 pm | Permalink

    Somehow that device seems way more complicated than it needs to be.

    I think that frame rate is the most important factor in film quality. I remember a company tried to start up back in the 80s with movies that ran at, I think, 60 frames per second (the standard is 24 fps). Their demo was impressive, the projected image was virtually indistinguishable from real life. They failed, probably for two reasons, one was that it required either huge film reels or many more of them, and two, it would have required theaters to replace their projectors with more expensive ones.

  10. Posted August 14, 2017 at 7:01 pm | Permalink

    I saw what I think was the very first IMAX film, North of Superior, here in Toronto at the Cinesphere. Here’s the link:

    And during this year’s Toronto International Film Festival they’re bringing North of Superior back to the Cinesphere.

    • dabertini
      Posted August 14, 2017 at 7:13 pm | Permalink

      Me too and at the same place. Great memories.

  11. infiniteimprobabilit
    Posted August 14, 2017 at 9:01 pm | Permalink

    Looks like Cinerama, rebooted.

    Cinerama originally used a curved screen and three synchronised 35mm projectors. Trouble was, the curved screen only really suited one area of seats at the centre of curvature** and you could ‘spot the join’ where the images met, also straight horizontal lines at the top or bottom of the picture tended to curve and have kinks at the joins. For more on the practical technical difficulties, see Wikipedia.

    (**In our Cinerama cinema in Auckland, this was the ‘cheap seats’ at the front of the balcony).

    Later on a single 70mm projector was introduced which avoided most of those problems. 2001 was screened in 70mm Cinerama. It was said that you could smell the marijuana as the local yoof took a couple of furtive puffs in the gents before returning to be blown away by the ‘beyond the infinite’ sequence.

    Cinerama sort of faded away as other techniques improved.


  12. Posted August 14, 2017 at 11:52 pm | Permalink

    A nice change of pace away from the terrible events at Charlottesville.

    The IMAX movie at the Smithsonian was indeed called “To Fly.” And it was marvelous.

  13. Posted August 15, 2017 at 4:35 am | Permalink

    It is called To Fly! I saw it back in 1990 as part of my ‘yuge’ round trip from DC down the eastern seaboard, across North Carolina, up the Appalachians, and via upstate New York and Connecticut. In 12 days. Not bad for a Limey.

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