VFX History: Optical Printers

Beyond the basic explanation of "blue screen", have you ever wondered how they used removed the blue from a background. These days compositing software makes it simple to select a colour and make it transparent, but before After Effects and similar compositing software existed, the entire process was done optically with physical film strips, lights and cameras.

Join me in a deep dive as I share with you what I've discovered about the labour intensive process involved. By the end of the video, I hope you'll be as awed as I am over the lengths companies like Industrial Light & Magic (ILM) went to in order to make cinema magic.

(I also feel that I should point out, the optical printers ILM used were "computer controlled" so that all the frames and timings lined up correctly. Everything was still composited optically.)

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*Chapters*
0:00 Old movies
3:58 A quick primer
5:37 An optical printer

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*Bibliography*

[ShiveringCactus]

In case you're wondering (and to save you pausing), the super fast text reads:

This animation is intended to illustrate how a movie camera with film works and it is not intended to be a simulation.

An iris controls the amount of light passing through to the film. It can also be used to control access to StarGate Command.

A shutter is the device within a camera which controls when a cell of film is exposed, but that element does not appear as intuitive as an iris.

Also the iris and/or shutter would both appear inside the camera body, behind the lens, not infront as depicted here.

Finally, while the effect of the exposing the negative looks kinda cool (at least I think so), it would most likely not appear in the manner depicted. It would most likely all fade on together with some elements continuing to darken, but this did not look as visually interesting.

There - that should address all your notes you may have had, so don’t @ me!

Oh...also... thank you for watching!!!


And the second one:
I've skipping over a ton of information here.

Initially COVER MATTEs for the layers are created, then combined to create the INTERMATTE.

John Knoll created a BLUE SEPARATION LAYER and then used the GREEN SEPARATION LAYER to create a COLOR DIFFERENCE MATTE for the blue colours, which was then combined with the GREEN SEPARATION LAYER and it is this that is used with the mix of Green and Blue lights.

I've not included this here as it is all very confusing and ultimately is just about the refinement process.

If you really want a deep dive, it is well worth checking out John Knoll's talk: Old School School 1 - Optical Compositing

[Jaspax]

Videos like this is what youtube was made for, definitly worth the 16 hour render

[tomkam]

This is a really comprehensive breakdown! Great job making this really complex process understandable. I worked at a teeny-tiny optical house in the 90s, first as an intern then became the title designer and built the animation cels and rolls to send to the animation camera. My boss tried teaching me how to use the optical printer and create optical line-up sheets...I was not built for such things. Something you skipped over but worth mentioning just to add more fuel to the confusion of optical compositing - was Density and Color Wedges. Every element that would be added to a composite had to be "Wedged;" a single representative frame from each element would be chosen and printed with every (reasonable combination of printer light - [ oh geez...printers had shutters over the RGB lights in the lamp house to control the lights...by varying the amount of light each color they let through you could adjust the color rendition of whatever you were printing, and where the term Printer Lights comes from]...) When developed, you would have a strip of film with dozens of that single frame printed in all kinds of colors from which someone in authority would have to pick from, BECAUSE, once photographed with the optical printer, your color for the finished composite was locked in (yes, I know...Hazeltine at the lab for color-timing, but you know...brevity!). As for Density, those mattes that are created from the red, green and blue separations when developed are black and clear. Black areas hold out light and clear allow light - and images - to be printed through. But the black areas need to have a certain density to keep light from leaking thru, so there was yet MORE testing involved - using a densitometer - when creating a matte to make sure it will print correctly. Almost final thought...I believe this is where Matte Choking derives from. Increasing or decreasing the exposure time for a matte will make a denser or less dense matte. But it also causes the black area to grow or shrink, one possible cause of matte lines around objects in a shot - and also why you see weird shapes surrounding composited spaceships in old video transfers - it's the difference from "Film Black" and "Video Black." There are a lot of variables. I'll leave it to you to explain why you can't just flip a piece of film over...or why you would flip the camera upside-down to filming reverse action. Thanks again for the memories!

[trackstick_travel]

I designed optical printer control systems. You can use a color wheel that rotates a set of filters to take multiple shots of the same frame. This way you don't have to rewind the film each time a new color is exposed. I hated these machines! They were so cumbersome to work on but I was one of the few people in the world that knew how to repair and redesign them to work better and more efficiently. The "Model C" optical printer was one of the oldest and most reliable. It used a paper tape for color adjustments but wasn't really for special effects. Optical printers weren't just used for special effects. They were used worldwide by Technicolor and Deluxe Film Labs to distribute movie film reels to theaters.

If you have any questions, I would be happy to tell you all the various parts of the filmmaking process related to pre and post-production. Burbank, where I reside, is a "coal mining town" where most of this almost 100-year-old technology was and still is occasionally used.

[Jimorian]

During the first showing of Star Wars on television, the differences in contrast in that medium meant that the garbage matts were *painfully* obvious on screen.

[keithartworker]

9:53 Fun fact: There was a mistake for 2 frames where the Millennium Falcon flies past the camera. Two tiny tie fighters were accidently exposed on the Falcon. It's a testament to how much coordination was necessary to pull off such a complicated shot. Thank you for this series. The "bipack" step answers a lot of questions.

[moocorp]

Finally took that 'I think I get it...' moment from a bunch of reading to the 'I get it now!' elation. Thanks for the work you've done!

[okankyoto]

Ah yes, this why when working as a compositor, nobody older than me remembers these days with much affection.

[MePeterNicholls]

Blimey. That’s a lot of steps and a lot of film!

[filanfyretracker]

And this is why digital combined with NLEs unlocked filmmaking for so many more people, I suspect a huge barrier to shooting even a short film was the cost of film stock.

I cannot imagine what effects heavy films must have spent on film alone.

[VariTimo]

Also back then they used tungsten balanced film for movie which’s blue sensitive layer is about a stop more sensitive than the others. Making the separation clearer and the transition to white easier.

[arthurdent]

Glad I paused that first one, lol. Nice reference hehe

[VECORlt]

Its kinda sad that all of this knowledge is slowly being lost due to being irrelevant, on the other hand the whole process is insane, so many processing steps, so much film, all this needs to be correctly exposed, aligned, combined, developed, whats even more mind boggling - after all those steps visual fidelity is still preserved!

[Meteotrance]

The blue color of the blue screen usualy didnt print on a black and white film they use a very high contrast one for making the alpha matte, but some clever guys at Disney Ub Iwerk and Petro Vlahos use to build a more complex system, with sodium vapor light on a blank screen, that make a special orange light that only show to a special prism build inside the camera with two films, one for the color footage and the other that separate the orange one for the alpha mask, it was use on Marry poppins and the Birds from Hitchcock.

[MarcHendry]

Those pointy "surface gauges" do have a use in stop motion, especially in the days before they had video previews of what they'd already shot. It helps you to track where something was on the previous frame as you're making the new pose. So, like, you point it to the character's fingertip, then when you move the hand, you know where it used to be.

[faldor]

Brilliant breakdown of how it was done old school.

[Locomamonk]

You need more views, man, this is fascinating!!

[DylanReeve]

I honestly struggle to imagine this. It seems impossibly complex.

But then I imagine what I sound like trying to explain linear online editing to young editors: "...and then the VTR had a feature called pre-read that would read the video frame and send it out and you could record it back on top of itself. So it would go out through the vision mixer, into the DVE, which would then return on another ME layer and we'd use a downstream key to apply the output of the Inscriber, and it would all go back, via the master matrix router to the VTR's input"

[QUIRK]

As I understand it, the huge drawback of this process was that each reproduction added the previous film's grain to the new, quickly leading to a buildup of graininess in composited shots. Apparently, one of Star Wars' big innovations was to use a VistaVision camera for effects shots, running 35mm film horizontally for larger frame size.

[UNIVERSOENUNACAJA]

I loved this video!! More of these please! ❤ now a lot of after effects and editing procedures make sense to me hahaha