Building a modular zoetrope


#1

So yesterday I was thinking about animation stuff and talking with a friend, and got the idea of building a zoetrope with the glowforge. And so, yes, let’s do it! Here’s the cut I made, out of a sheet of 1/8" draftboard; not pictured is the alternate animation I then scored into the other side of those plates, having taped the board itself down to use as a jig to keep the (symmetrical under a rotation) plates in position when flipping 'em.

My basic idea: build it as a generic base with a circular center hole for a turning device and equally spaced square slot holes around the perimeter to insert animation plates into.

That way the animation plates themselves can all be free-standing, independent pieces, and animation designs can be worked out as a sequence of images overlaying that generic piece.


#2

A traditional zoetrope uses a continuous strip of paper with carefully spaced animation frames running along it, which then sits inside the device below the level of a row of corresponding slits. The viewer looks through the slits while the zoetrope rotates, and gets little stroboscopic glances of the animation frames, producing the illusion of animation.

But with this construction, you don’t need a separate row of slits above the animation frames: the narrow spaces between the individual animation plates function as the viewing slits, like so:


#3

Arranging the animation plates in the base is simple enough if you organize them somehow; I scored (in in retrospect a poor choice of type+size treatment) frame numbers from 01 to 24 in the bottom left corner of one side of the plates, in case I manage to spill them everywhere and lose the order.


#4

And, there it is!

My animation choice (an outlined treatment of a Conway’s Life glider looping across the frame) turned out to be not great in terms of visibility, even after I took a colored pencil to it to create some more fill contrast, and the lighting in my living room this evening is dim enough to make for poor videography in general, but the concept is definitely there!

I’ll look into playing with some additional animation ideas in the next few days, to see what might work better for this kind of slightly smeary rotational treatment, and see if there’s any tweaks to the design that present themselves to me.

I used my turntable for rotation, but in principle this would work fine with just a pencil and a steady hand.


#5

Very nice.

Taking a video of it is always going to be difficult because there is always going to be a conflict between the frame rate of the Zoetrope and the camera.

Since you have 24 frames it looks like you are targeting a one second loop at standard movie speed of 24 fps.

At 60 rpm you will see one loop in one second - 24 frames per second.

A turntable gives you two choices.

At 33 1/3 rpm you will see a one loop in approx 1.8 seconds - 13 1/3 frames per second
At 78 rpm you will see one loop in approx .77 seconds - 31.2 fps

You video is recording at 30 fps so you would need a speed of 75 rpm to match that.

Even if you match the 30 fps your effective shutter speed will be determined by the size of the gap. For arguments sake let’s say the gap is 10% and the tile is 90%. You shutter speed would be 1/300 of a second.

The problem is that your camera’s shutter must sync precisely with the Zoetrope or you won’t get a good recording. That is the same reason you see banding when video taping a CRT. The camera is only catching a portion of the screen refresh.

Probably TMI but there it is. :wink:

In any case it is an awesome job and I bet it looks fantastic in person.


#6

Yep, there’s a whole interesting pile of issues with trying to film this, between fps mismatch and rolling shutter artifacts. I gave it two seconds thought last night when I started to film and then just laughed and moved on because boy howdy am I not gonna worry about solving those problems right now. :slight_smile:

As you say, looks much better in person. I’ll fiddle with the design a bit more but the first take was more effective than I’d expected.


#7

Cool project, would love to see it go in person to get the full live effect!

Dig the cellular automata glider as your choice of subject matter too.


#8

Is your table turning the wrong direction? Haven’t had one in a while, I dunno, maybe that’s a thing they do now …?


#9

It is running in reverse! This model will do that without complaint, though I have no actual music-listening need for it. Saved me the trouble of reversing the order of the animation plates once I realized I’d put them in in the wrong order.


#10

Love zoetropes. I’ll get around to building one someday, but until then, I’ll just admire yours. :grinning: