How to make a zoetrope

A zoetrope is a drum with sequential animation stills facing inward around the circumference. The viewer peers through equally spaced viewing slots toward the images on the opposite wall. An open top allows light to enter and illuminate the images. As the drum spins, the slits provide broken views of the drawings or photographs, creating a strobe effect and the illusion of a moving image.

Lauren Nordhougen, Reliving the News, zoetrope with image strips, 2009.

The Chinese inventor Ting Huan invented the device first in 180 AD. His version hung over a lamp and would turn from the hot air currents that the lamp produced. In the western world, the zoetrope was reinvented in 1834 by the British mathematician William George Horner (1786-1837). He called his invention the "daedalum" or “Wheel of the Devil.” Forgotten for 30 years, the animation machine was finally patented in England by M. Bradley and in America by William F. Lincoln and dubbed the "zoetrope,” Greek for "turning zoo" or “wheel of life,” similar to the thaumatrope. 

In 1980, independent filmmaker Bill Brand created a linear zoetrope in a subway platform in Brooklyn, New York. When the train passed through the station, viewers inside the cars would see a moving image through the window of the train. Capitalizing on this idea in 2001, entrepreneur and astrophysicist Joshua Spodek turned Brand's linear zoetrope into an advertising scheme for subways all over the world. These advertisements are approximately 500 meters long and 30 seconds in duration. They use illuminated transparencies with a photographic quality that, when animated, looks just like high-definition video.

Artist Chris Landau created the image sequence Flap-Trope, in which “the bird forces herself in and out of the animated scene in an impossible, never-ending loop.” Here, we follow Chris’s methods for creating the zoetrope and animation stills. These instructions provide a guideline that can be altered for your own purposes.

Chris Landau, Flap-Trope, 2006, zoetrope and animation sequence.

Materials

• A digital or film still camera
• To edit the image size and print, you’ll need a darkroom or a computer with Photoshop and a digital printer.
• A drum: You can make a drum out of an existing cylindrical tube (a round ice-cream bucket, 12” schedule 40 PVC pipe, etc.) or construct a cardboard drum.
The board drum is made up of            
            • a base: a circle of matte or 4-ply museum board that will ultimately be glued onto the rotation
              device.           
            • a side wall: bendable board, such as 2-ply museum or card board, which will hold the images 
              and the slots for viewing.
            • connectors: a ring of saw-like teeth made out of museum or card board, attach the sidewall to
              the base.
• A rotation device: build the rotation device from scratch or use a found object, such as a “lazy Susan” or record player. Spinners that slow down quickly won’t give you enough time to become absorbed in the illusion.
• Other tools: A sharp utility knife for cutting board, a pencil, ruler, removable tape such as drafting tape, white or PVC glue, weights to help the board/glue dry flat, hot glue sticks and a hot glue gun.

Zoetrope Strip Instructions

The zoetrope uses the principle of persistence of vision to create the illusion of motion. This principle states that the effect of light on the retina chemically persists for up to a tenth of a second. Old movie projectors flicker because they are just below the noticeable 10 or 12 frames per second. Up until the point of 24 frames per second, the faster a zoetrope spins, the smoother the animation. The zoetrope creates a stroboscopic effect. A black border in-between frames isn’t necessary, but can provide a way of jumping from one image to the next, protecting the retina from light. This border can be inserted in the layout or can be present in the subject when filming (i.e., a shadow at the edge of the frame).

Drum base and rotation speed

Specifications for the number and size of animation frames in a strip, the circumference of the drum, and the number of slits depend upon your drum's speed of rotation. The speed of rotation is determined by the rotation device and the power source (mechanized or hand-operated). In this example, we use a plastic "lazy-Susan" that rotates at about 2 rotations per second. You will want a lazy-Susan that turns well and keeps a consistent speed. Because of the ball bearings, our lazy-Susan spins with very little friction. If you want a reliably steady speed-rate or a hands-off zoetrope for an exhibit, you may want to use a motor to turn the drum. A battery would work as power source, but would have a limited lifetime. Count off how many times your device rotates per second.

Rotation speed and frames per second

Once you have established the rotation speed, you can determine how many frames per second you want your animation to run. The more frames per second the better you trick the eye. Ideally, you will have 24 frames-per-second. The minimum is 12. If you have a zoetrope that can spin at one rotation per second (which is fast) you will need 12 frames to get rid of flicker. Such a fast speed is probably too much to ask of the zoetrope, and many people actually enjoy the flickering quality of this old technology.

Our rotation speed is 2 rotations per second. With 24 frames around the circumference of our zoetrope, we have a 48 frame per second animation, fast enough to create the illusion of motion.

Calculate the circumference of the zoetrope 

Decide how big the zoetrope will be. This will depend a lot on the materials or objects you are using to build the device. The most important dimension is the diameter of the drum. The diameter will help you figure out the circumference or perimeter of the circle. Use this equation to figure out how wide your image will be: 

"C = D x pi" (where C is the circumference and D is the diameter).

Multiply the diameter by pi (3.14). The diameter of our zoetrope is 16 inches so our circumference comes out to 50.25 inches. That's a little over 3 times the diameter, which is a good way to check your calculation.

Determine the width of each image

Once you know the circumference and the number of images/frames, you can calculate the width of each image/frame. Image width can be determined using this equation:

“w = (2 x pi x r) divided by f” (where w is the width of each image, r is the radius of the circle, and f is the number of frames).

For example, with our zoetrope:

2.093 = (2 x 3.14 x 8) divided by 24

We then round 2.093 to 2”.

Record the movement

Before constructing the actual zoetrope, record a movement. Remember that the animation must continuously repeat in a loop, which presents an interesting challenge—connecting the final image of the sequence with the first. The action of the final image of the sequence must continue in the first image.

To connect image frame to image frame, you could work with a continuous-looking sequence, such as ours, in which each image touches the following and preceding ones. Or you could think of each image as a separate picture, surrounded by some amount of empty space. As long as they are spaced (fairly) equally with the view slots, it doesn't matter which strategy you use.

For a smooth flowing animation, photograph a series of stills by moving your subject in small increments between exposures. For a more jerky animation, use larger time increments between shots. You might lock the position of the camera using a tripod or placing it on a steady surface so that the camera movement does not detract from the movement in the scene. Make sure to create enough images to fill the entire strip, in our case 24 images.

Adjust the images

We do the next series of adjustments in Adobe Photoshop, though you could do them in the darkroom or with collage techniques. In Photoshop, make any contrast or image adjustments (images should be high contrast).

Resize the images

Resize the images to the correct dimensions by selecting Image > Image Size. Make sure your resolution is 300ppi for high quality printing. Then, check Resample Image (so that the Resolution is no longer connected to the height and width values). Set the dimensions. In our case, each image must be two inches wide, so we enter 2” as the width and allow the height value to change accordingly. To resize all the images, record the resizing process as an action (Window > Actions) and apply a batch action to your folder of images (File > Automate > Batch; or see the book’s index: Actions.).

Determine the number of sequences per printer page

If the total circumference of the drum is longer than your paper, you may need to break the animation up into a few sequences and then paste the strip together after printing. We will definitely need to do this, because our printer won't print 50.25 inches. Instead, we will fit three mini-strips of four images each on one piece of paper.

Create a template

Set up a template for the images so that they will all line up in a straight row. Use Photoshop’s guides and grid to help with this. In Photoshop >  Preferences > Guides, Grid & Slices, setup guides and grid preferences. Specify the color and spacing of gridlines (we chose red every two inches with two subdivisions). Click OK. Go to View > Show > Grid to make the grid visible. Open the first image in the sequence and use the Move tool to drag the image to the layout. Drag it within the first grid square and press the Up Arrow or Down Arrow keys to move the image incrementally until it is perfectly placed. Use guides to help align the image. Open View > Rulers, and View > Show > Guides, then drag a guide from the ruler to the layout.

Once the layout is complete, print each sheet. Carefully trim the mini-strips and tape them together on the back to form a larger strip, the loop.

Construct the Board-Based Zoetrope

Once you've printed your strips, you're ready to build the zoetrope. First, you will want to measure and cut out your the parts of the drum. These include the side wall, the base and the connectors. The side wall is going to be the circumference of the drum and so are the connectors, which have teeth like a saw (see image). If you rounded out the dimensions of your animation stills, you may need to recalculate the circumference. In our case, we rounded the width of the stills to 2”. This means that our new circumference is 48” rather than 50.25”. To create a drum with a 48” circumference, we have to splice together several pieces of paper and board to get the side wall and connectors.

Construct the base

The base is essentially a large cardboard circle. If you don’t have a compass that will draw a circle this big, make your own with a strip of thin board. Pin one end of the board to the matte board (which will become the base) to create a kind of propeller. Another hole (big enough for a pencil tip) turns the propeller into a compass. This way, you can make a hole as big as you like. But you’ll want a very specific size for your circle. The distance between the pin and the pencil is the radius of the circle, which, in our case, should be 8”.

Construct the side wall

The side wall should be at least twice the height of the animation stills. This provides space at the bottom for the strip of images, then an equal height space for the slots, and at least half an inch of board at the top to stabilize the slots. Before cutting slots, test the size of the wall and the size of the image strip by temporarily curving the wall into a drum and placing a strip inside. The strip should fit perfectly into the drum, without having to use adhesive.

The slots along the side wall/drum are like shutters. When our eyes look through the slots, they require a certain amount of exposure to light. These slots must be evenly spaced around the cylinder, and there should be an equal number of slits to images (1:1). A reasonable width for the slots is approximately 1/8th of an inch. Any smaller and the image won't register, any larger and the image will persist in the eye for too long.

To determine the width between slots, measure the cylinder's outside circumference and divide it by the number of frames. Subtract the width of a slot from that number to determine the distance between each slot.

Construct the connectors

The connectors' side wall (which will be glued to the main side wall) should not be taller than the animation stills. The connectors’ teeth allow the drum to be glued to the base. Space the teeth enough (no more than an inch) to enable the connector’s side wall to curve into a drum. To make sure that the teeth don’t overlap, make them at least 60 degrees (like shark's teeth). Once constructed, fold the row of connectors, just at the line of the teeth.

Assemble the zoetrope

Tape the connectors to the outside of the side wall and then to the base. The tape will temporarily hold everything together while you apply the glue. Pick four "teeth" from the connectors and glue them into place, directly onto the base at the edge of the drum. Then, tape them to hold them in place. Once those dry, glue the rest of the connectors around the base. Let the glue dry and remove the tape. Then, remove the side wall, which was only connected by tape.

Now, the inside wall of the connectors is exposed. Place a bead of glue every inch along the inside of the connectors' walls. Squish the side wall into a kidney bean shape and carefully allow it to open up inside the connectors, against the glue.

Glue the bottom of the drum's base onto the "lazy-Susan". Hot glue is a good way to attach the drum, just in case you don't center it correctly the first time. You won't need very much glue, but work quickly or it will cool and loose it's tack.

Spinning Suggestions

Place the image strip inside the zoetrope. Hold the center of the zoetrope under a light to illuminate the images during animation. Spin and peer through the slots to animate.

* All photos of zoetrope process taken by Chris Landau. Adobe product screen shots reprinted with permission from Adobe Systems Incorporated.