Hello, gentle readers. I’ve had a busy couple of months working on various art projects in my studio, so I felt that a blog update was long overdue. One of the projects that has kept me occupied lately is the creation of an animation device called a phonotrope.

What is a phonotrope, you might be wondering? It’s a contemporary update to a zoetrope, a 19th-century pre-cinema animation device consisting of a cylinder with vertical slits and a sequence of still images placed inside. When a zoetrope is spun rapidly, a viewer can peer through the slits to see the animation. These devices were very popular as toys and entertainment in the era prior to the advent of moving pictures on film.

The phonotrope works on a similar principle to the zoetrope, but replaces the cylinder and vertical slits with a record turntable, lights, and a video camera. A polar grid is designed with a certain number of frames, and a sequence of images is printed onto this grid. The grid is rotated on the turntable at a certain speed, with the animation made viewable when seen through a video camera set at a specific frame rate — the animation cannot be viewed with the naked eye. Other phonotropes have used a strobe light in lieu of the video camera to make the animations viewable, but I’ve found my images appear much crisper and clearer with the camera.

Now, your goal with the phonotrope is to first find the “correct” number of frames so that the image will appear relatively static or stationary when rotated on the turntable at a certain speed. Since I’m the least likeliest person to ever figure something out using math, there was a lot of trial and error with this part of the process. After a few trials, I discovered that I could stabilize an image using either 12 or 24 fps with 32 frames. If I had less than 32, then I would see the animation working but the image itself would drift on the turntable. With 32 frames, your image area is quite small — 1.158″ wide, to be precise. This very small space created a design challenge, but I reasoned that my images could be as tall as I wanted if I oriented them vertically, hence the vertical rings of printed paper for my phonotrope.

Since the 8-inch diameter circle requires fewer frames (16 frames rather than 32), each frame could be slightly larger (1.5″ wide). With only 16 frames, the frame rate needed to be half as slow at 12 fps. Fortunately, the 32-frame animated loops still work at 12 fps (12 being exactly half of 24) but also be half as quick. Given how quick and frenetic these loops can appear, having the 32-frame loops moving slower was a definite plus as it makes the action easier to see. 

Here are the specifications for my phonotrope:

• Two rings of vertical paper, one 12-inch in diameter and the second 8-inch.
• The 12″ circle has 32 frames.
• The 8″ circle has 16 frames.
• The phonotrope is rotated on the turntable at 45 rpm.
• The smartphone video used to capture the animation is set at 12 fps.