Slow Dance Appears to Make Time Run In Slow Motion

Rendering something in slow-motion is an often-used technique that attempts to add some ‘wow’ or ‘cool’ factor. Seeing something out in the world move in slow motion is marginally rarer — rarer still if it’s in your own home. But do it right and that kind of novelty turns a lot of heads. Enough to go 8x on a Kickstarter goal.

Slow Dance, a picture frame ringed with strobe lights, generates the surreal effect of turning small, everyday objects into languid kinetic sculptures. It’s an intriguing example of kinetic art done in a novel way.

[Jeff Lieberman], a veteran of high-speed photography, takes advantage of ‘persistence of vision’ by synchronizing the vibrations of an object — say, a feather — with a strobe light blinking 80 times per second. An electromagnet inside the frame is used to vibrate the objects, while the strobe lights are housed inside the thick frame.

Slow Motion In Action

There are a couple different slow-motion effect settings, and the device is likely limited to small, flexible objects, so don’t go overboard with whatever you decide to strap into a Slow Dance frame. Of course, slow-motion isn’t limited to this dazzling frame and cinema — a Rube Golberg machine that takes six weeks to finish will do just fine.

[Thanks for the tip, Itay! via ThisIsColossal]

27 thoughts on “Slow Dance Appears to Make Time Run In Slow Motion

  1. Really interesting! I wonder how resilient a living plant would be to vibrations for a ‘fern lamp’ or similar. I did see the note that flowers don’t last very long.
    Nice animated GIFs; great looping.

    Kudos to [Jeff Lieberman] and the rest of the Slow Dance team. I won’t purchase one but I sure do want to replicate it!

    1. “How loud is this thing?
      Incredibly quiet. The loudest thing is the object itself moving through the air, and the magnets can be adjusted to change the ‘volume’ of movement, so if you make the movement very large, it will create more noise. I can’t hear a feather from 10 feet away in a quiet room. For the techies out there, I have no decibel meter, but I’d estimate it’s around 30dB.”

    2. You have a point there. But for some reason I’d still prefer the continuous 80Hz instead of the hypnotic music that was used in the video. Still… the “wow factor” in this one is very strong.

      1. LED’s are bright, small can be easily driven and most importantly, they can switch really really fast. That is if you use pure LED’s, the modern white LED is a blue LED with white phosphor, that make it much slower (because the phosphor keeps glowing for a very short while when the blue light is off, but I assume it to be good enough for this purpose). Therefore LED’s are the perfect choice here.

        1. Thanks for the reminder about ‘white’ LEDs…
          I’ve been pondering about a dimmable headlamp that I have on hand. Very noticeable flickering at the lowest setting…
          Time to run a tone generator on my phone and connect an external speaker, going to vibrate some plants a night. :)

          If anyone wants a great tone generator for Android (free, open-source, no weird permissions):
          https://github.com/billthefarmer/sig-gen/wiki
          You can download it from the F-Droid program and it works beautifully on my S5 smartphone. Has sine, sawtooth, and squarewave settings. I assure you it can output subsonic frequencys you just need an external speaker and not Bluetooth.

      2. LEDs are what they use.

        As for the speed of phosphor white LEDs, that’s definitely more an issue for high-speed data communication than photography — you’re looking at decay times well below a microsecond. If you drive the vibrations at 80 Hz, 1 microsecond is less than 1/10000 duty cycle — which means your light needs to be more than 10000x the intensity of ambient light. This seems impractical except in the darkest rooms, and anyway is faster than needed to freeze motion. Indeed, it may be too fast, and freeze motion too sharply. There’s an argument for having some motion blur on each frame, but less than the total frame-to-frame motion. (Traditional movie cameras had a shutter angle of 180 degrees, which means an exposure of 1/2 frame time, so we’re definitely culturally acclimated to that value, but it’s not clear if this is actually optimal for perception of motion.) If you assume 80Hz for the driver, and 79Hz for the strobe, it’ll go through 1/80th of the cycle per frame, so you’d probably want a duty cycle between 1/80 and 1/320. (That results in 1 cycle per second — the video looks a little slower, but can’t be bothered to time it.)

        My first guess would be to run about 1% duty cycle (or about 125 us on-time), and spec LEDs to reach about 500x ambient. For typical domestic lighting of ~50 lx, you need daylight-level illumination, but with the 1% duty cycle, the average power (and cooling) requirements remain low.

        Obviously you’ll wind up with a brightness control, whether manual or photocell-driven, and at least on the prototype, you can implement that by just varying the on-time, so you easily get a couple orders of magnitude of brightness control, and can experiment to see whether too-short pulses pose an issue or not.

    1. 250!!! that is a lot of money (considering it’s mainly a vibrator + blinking light in a frame). But then again, we don’t have to buy it. Actually it is better is fewer people buy it. Why, well if this item was to be in every home it would loose its appeal. The high price is therefore mainly required to maintain the exclusiveness (or illusion) of the effect.

      1. You know, people need to pay their rent and feed their family somehow. Please just recognize that they’ve made something unique and put time and effort into developing this product. Just because we’re used to mass-manufactured products these days doesn’t mean that low-volume, unique products are much cheaper to develop and manufacture.

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