Creative ambitions of directors like Bob Zemeckis push visual effects technology forward, and for Back to the Future 2,
he insisted on another breakthrough that would profoundly impact the way we shoot effects films today.
Between all the flashy flying cars were scenes of characters
interacting with themselves from another time. The same actor playing both parts through the use of the second-oldest effect in cinema history,
the split screen.
Early filmmakers would do split screens in-camera by blocking part of the frame on the matte box
filming one side of the shot and leaving the other side unexposed.
Then they'd wind the film back,
swap the matte, and shoot the opposite side while preserving the already exposed side. As long as the camera stayed still, and the seam of
the double exposure could be disguised on an object in the shot, it worked great.
They were even getting fancy with it pretty early on. A good example is the 1921 Buster Keaton film "The Playhouse".
Here he is portraying members of an entire orchestra,
some stuffy audience, comedians onstage and a- Oh, oh, no, let's get out of here.
70 years later,
Robert Zemeckis was determined not to compromise the cinematography
of Back to the Future 2 with static angles and artificial pans and zooms
for the split screen shots. He wanted the camera to move freely as in the rest of the movie.
So in each of these seemingly simple dialogue scenes,
it needed to be driven by a motion control system in real time.
Of course, these days, real-time motion control rigs
are available at every corner web store
but in 1988 there were a little hard to come by.
Some early ones developed by pioneers like John Whitney and Bill Tondreau already existed,
but these were cumbersome machines,
impractical to transport, and way too noisy for dialogue scenes.
So an entirely new silent and portable system had to be created by Industrial Light and Magic
engineers Mike Bolles, Udo Pampel, and Mike MacKenzie,
especially for Back to the Future 2. It was called the Vista Glide. Built on a modified
panther dolly, it could move in a linear track, boom vertically, and operate a
200-pound Vista flex camera with perfect repeatability.
It was the most advanced system of its time.
And we're gonna take it for a test drive. To help me demonstrate how the moving split-screen shots were done,
I've called on the acting talent of London-based youtuber, and fellow Back to the Future fan Ami Yamato.
Ami: Hello!
CD: Are you ready?
AMI: All set.
CD: Excellent!
CD: But we won't be using an ordinary slate for our scene.
Instead we'll trigger the whole system and mark the exact same start frame each take with a bloop-light.
CD VOICEOVER: We begin by carefully planning the scenes blocking and camera angles.
Then the camera rolls and Ami acts out the A-side of the conversation,
while a stand-in reads the other lines.
I operate the camera and the Vista Glide records every nuance of the movements as they happen.
When we finish a take we're happy with we have to commit to it because Ami leaves her cup in a spot from which her
doppelganger will pick it up. It's very important that nothing on the set moves a millimeter, or we'll have to start over.
During the most complex motion control scene in part 2 when Michael J. Fox
plays three members of Marty's future family filming took three days. And all the props had to be glued down to ensure
consistency. The shoot was nearly ruined when an earthquake struck and moved the Vista Glide rig.
Luckily they had just finished filming three hours earlier. Back on our set,
Ami's transformed into her second character through the magic of wardrobe and makeup.
We relaunch the Vista Glide, programmed with the motions of our earlier chosen take, and a video system plays back the take itself.
Hearing audio of her own performance, Ami acts out the other side of the scene as the camera repeats its motion in perfect sync.
By the way,
each axis of movement in a motion control rig is handled by a channel,
and in the Vista glide, there were 16 of them.
Which means it could control more than just the camera. In a few split-screen scenes throughout the sequels, it also moved
objects in the shot. When Tom Wilson passes the almanac to himself in part 2, his hand actually
rests on a rod to which a solid metal replica of the book is securely attached. A motor rotates
it across the split-screen boundary in sync with the camera move and on the B-side
it's the hand of a double. In part three the plate Michael J
Fox hands himself as Seamus McFly is also controlled by a rod later removed with a clean background pass.
With both sides of our scene finally filmed we can roughly combine them on set to make sure things line up and
of course they do. Because the Vista Glide is awesome, and so are the ILM engineers!
CD: And so is Ami Yamato.
All right, well...
See ya!
Ami: Wait, aren't you going to take me back to England?
CD: Oh, yeah, just talk to someone in the production office,
I'm sure they'll take care of you-- all right people, we're moving on! Lots to do!
There was still the small matter of creating a clean optical composite of the split-screen footage. Using a traditional
animation stand they shot backlit cells with carefully painted shapes that defined the exact split.
The camera mount on this animation stand was also motorized and could be programmed with keyframes. So the shapes were
visually match-moved to the camera motion in the scene.
This black and white matte was then used in the optical printer to expose one side of the film frame at a time for the
final composite.
And they didn't have to hide the splits on obvious lines in the scene.
ILM optical departments Stewart Robertson and John Ellis
figured out how to make the double exposure edges almost completely seamless.
The splits could sit in the middle of anything and even fade to a different spot during the shot.
This is what made it possible for characters to hand things off to each other and cross into each other's space.
If it sounds complicated,
it was. Because the high quality picture had to stay on weird strips of cellulose acetate every step of the way.
But then, as part two was being finalized and part three went into post-production,
history began to change...
Film scanning and digital manipulation tools were maturing and ILM's computer graphics department was taking center stage.
Sandra Ford Cartman was one of its earliest members and worked on all kinds of subtle
enhancements to Michael ante Aries physical effects throughout the sequels
Wire and rig removal and the hoverboard sequences this crazy moment when the DeLorean pops a wheelie on the train tracks
Cables connected the nose to Aaron's hidden in the cab
Also digital blue screen work during the climactic train scene because it was impossible to key Mary Steenburgen's purple dress
Optically without severely shifting all the colors in the picture.
ILM had come a long way from the pencil drawn lightning bolts in the first film
But there's one shot that perfectly captures the evolution of effects in the entire trilogy
Fittingly, it starts the middle act of the second movie when Marty and Doc returned from the future to drop Jennifer off at her house.
The DeLorean flies, makes a clean landing pulls into the driveway, and Einstein strolls out of it-- a seemingly unimportant
moment depicted with an incredibly complex visual effect in true Zemeckis style.
Just think, a motion control split screen is being used to hide the real car driving off a
platform on the right side of the post with a pass of the empty street
Then a detailed miniature DeLorean, lit and animated to line up perfectly with the real one (by Peter Dalton) using nothing
but his eyeballs, is shot in multiple passes optically composited into the scene and rotoscoped to disappear behind the post.
To me the moment the DeLorean touched down in this shot is the moment the visual effects industry truly came of age.
It proved that effects are not just for spectacle. That they can become an
indispensable part of visual storytelling and films of all genres.
And sure, they're not perfect in Back to the Future.
The whole trilogy is full of imperfections.
The headlights aren't reflecting on the miniature side here the cap is cut off by the split screen in this frame
Marty's got three hands for a moment a diffusion silk and a flying rig are clearly
Reflected the stunt guy has a super red face. Hello short shorts
you can see a little wheel there and doing the heartfelt conclusion of the entire journey this little guy is pointing at his--
*Train horn sound effect*
But you know what? I've honestly never noticed any of these flaws. I got swept away by the story, and I still do.
When I watch Back to the Future today,
I still root for Marty, laugh at Doc and get goosebumps when the time machine appears on screen.
And as much as I know about the details of the visual effects,
I forget they're there.
All I see is an epic cinematic adventure.
It managed to remain
timeless.