bullettime

Slow motion, and bullet-time, are actually useful scientific tools. While we know them mostly as dramatic cinematography, the ideas and concepts are great for scientific analysis. Also, it looks cool, which is why a NASA engineer and his buddy built a low-budget version for an expensive camera.

Visual Acuity

Here’s the device in question, in action:

Which is undeniably cool… but how do they pull that off?

Bullet-time is a mixture of two principles. The first is pretty simple; the more frames you have, the slower an action is on film. Ironically, you create slow motion in a traditional film camera by running the film through faster.

However, that slows everything down, including camera movement, so bullet-time shoots hundreds of frames generally while circling the subject. The Matrix essentially set up dozens of DSLR cameras to fire in sequence to make its bullet time shots. This tries moving the light, not the camera.

Done With Mirrors

Essentially, it’s just two mirrors on a motor. The first mirror captures the light and reflects it to the second mirror, which reflects it into the camera. In this case, the camera is a Phantom, an industrial slow-motion camera used on shows like Mythbusters, which can shoot up to 72,000 frames per second. That part’s expensive, but you could build this and sub in lots of camera as a replacement; in theory even an iPhone 5S would work.

Constantly Improving

bullettime2

Of course, the downside, as those same iPhone 5S users can tell you, is that slow motion needs an enormous amount of light to actually work. Similarly, it’s hard to shoot the footage so that the rig actually gets out of its own way, and the focus will be rather soft due to having to use a lens and fully open it. But make no mistake; this makes bullet-time much easier for everyone to use.



Dan Seitz

 
Dan Seitz is an obsessive nerd living in New England. He lives in the Boston area with a fiancee, a dog, a cat, and far too many objects with processors.