After looking Douglas Trumbell’s schematic for his Slitscan device, I decided that making a modern day scaled down model wasn’t totally out of reach - Although I may have underestimated how difficult it would be.

Mech Slider

Like most mad scientist-slash-filmmakers, I had a mechanized slider lying around. I built this a couple years ago by adding a timing belt and pulleys to a slider with the intent of being able to automate the movement.

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On one end of the slider, I connected the end pulley to unipole stepper motor which was controlled by a USB controller. Stepper motors are good for this application because they allow precise reproduction of movement.

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LEGO Gizmo sideview without Slit

On the other end of the slider I attached my LEGO carriage gizmo with a large clamp. Built out of LEGO Technic gears and bricks which I had since I was a kid, this gizmo draws power from slider’s timing belt, sends it through some bevel gears and a chain where it turns a worm gear. This worm gear slowly rotates a large gear on which the artwork carriage sits. The artwork itself is transparencies with various patterns printed on by an inkjet printer.


Sample of Artwork printed on Transparency

In between the gizmo and the camera I placed a piece of cardboard a large slit. Using gaffer’s tape I was able to get the size of the slit down to about an eighth of an inch.

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Creating the raw film for my stargate is really a matter of creating a timelapse with a long exposure. The stepper motor is controlled by my laptop where I can tell the motor which step to run to. I designated ZERO as my extreme close up - I gave myself a little more room so I had some space to ramp up for speed - usually setting up at step 700 - the numbers are backwards just because of how the system was set up.. From 700 I would engage the motor to head to negative 7000. Watching the motor countdown on the computer I remotely released the shutter roughly when stepper motor hit Zero. The camera would then shoot for a 20 second exposure - shooting at F22 and ISO160.

The motor travels at 300 steps per second so the shutter snaps shut right around step negative 6000. The camera would continue to travel to negative 7000 - a little extra room for deceleration. - now that’s one exposure done.


Raw Frame from Camera shot with 20 second exposure at F22 and ISO160

Then it’s back to 700 to set up the next exposure. Once the camera is set to go again, I advance my artwork carriage first by releasing the power chain on the gizmo and then spinning the worm gear one half turn before reattaching the powerchain. Then it’s the whole process over again for the next exposure.


On and on it went. At maximum efficiency I could do about 50 frames per hour - 20 seconds for the exposure, 20 seconds to reset, 10 seconds to advance the carriage and a little left over for miscellaneous activity.


Although the way I describe the process seems straight forward, actually coming up with the setup was anything but. What works in theory always finds a thousand complications in application. First off, LEGOs aren’t exactly the most durable building materials - the first 3 of the 5 redesigns for the gizmo were the result of dropping the it and trying to collect the pieces after they shattered across the floor.

On top of that LEGO gears have some give in them which isn’t great especially when working on a small level that this model is. But Legos are easy to assemble and experiment with and they were what I had available.

Trying to dial in the speed of the carriage was another difficult thing to accomplish. I tried manually moving the transparency and moving the carriage itself but It wasn’t until the final design which used a worm gear which I could rotate to fine tune the position did I get results that I found satisfactory.

Slitscan Machine

Douglas Trumbull's Slit Scan Machine

For 2001, Trumbell’s slitscan machine pulled focus throughout the move and did slight pan left or right to fill the frame with the light streak - both of which I was unable to reproduce. His movement was 15 feet whereas my model only ran about 3 feet and his slit for his artwork was 4 feet high - mine was not more than 6 inches.

But unlike Trumbell’s machine which was fully automated, I had to babysit mine - making small adjustments for each exposure. Again and again and again...

But to my advantage I have HAL, or rather After Effects. Using After Effects, I could duplicate and stretched out my image sequence, and apply nifty color effects to create my very own slitscan stargate.

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There’s nothing quite as humbling as spending a 12 hour day creating 16 seconds of footage.

As much as I have a deep appreciation of how they did it back then, I have a much deeper appreciation of just what is possible today. Slitscan has been replaced with digital processes that can accomplish much more and much more easily.

The filmmakers who came before us didn’t have CGI, not because they thought practicals and models or optical effects were better, but because it just wasn’t available to them. But these filmmakers still strove to make the best stories they could with what they had available. Some succeeded triumphantly like Stanley Kubrick and Douglas Trumbell with 2001, but many times, as history has forgotten, some have failed. I don’t think the spirit and the need to stories has changed much... Just the tools that we have available to us. The filmmakers before us created great works in spite of their technology.... So what’s your excuse? Go out there, experiment, and make something great!

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