Immovable object, irresistible force

This is another of our fun shoots, carried out at our warehouse studio.

rope breaking_red

We thought it would be fun to see what actually happens when something breaks under tremendous pressure, and to take a shot of it as it happens.

So, we started off with a piece of 12mm diameter polypropylene rope, it’s pretty strong stuff, you could dangle a transit van from it. The rope was tied to one of the massive RSJ’s that supports our building, and became our immovable object.

And ourĀ irresistible force was our fork lift truck. We simply looped the other end of the rope over one of the forks, and used the power and weight of the fork lift truck to stretch, and then break the rope.

You can see in the video that once we’d put the rope under a bit of tension I make a small nick in the rope at the point where we wanted it to break, so we could be sure that the camera would be pointed at the right bit. And I rubbed a bit of flour into the rope, around the breaking point, to add some drama – which worked pretty well.

Lighting was very simple, with one of our SuperFast flash heads each side of the rope and slightly in front of it. These flash heads were each fitted with a standard reflector and their job was to light their own side of the rope. And behind the rope, off to one side a bit, was a 3rd SuperFast head, this was backlighting the rope at the break point and was fitted with a 10 degree honeycomb to avoid lens flare.

We used SuperFast flash heads because no other flash head could possibly freeze the action of the rope breaking under tremendous pressure. Some people will probably say that speedlights could do it, and so they could – but only when set to such low power, to get the short flash duration, that there wouldn’t be enough power for the shot unless the ISO setting was set at a ridiculously high level. Using the SuperFast, set at pretty low power, we were able to set the camera to f/18 at an ISO of just 200!

The theory was simple, but of course it didn’t turn out to be quite as simple as we expected. It was obvious that the rope would stretch before breaking, but we didn’t expect it to stretch quite THAT much! I’d set the camera up on a stand, with the nick in the rope at the top of the frame, expecting it to stretch to somewhere in the middle by the time it broke, but the stretching just went on and on and so we had to reposition both the camera and the lights several times before we got it right.

Once we had finally established the break point it was simply a matter of machine-gunning the camera, shooting at its maximum frame rate of 7 fps, until the rope broke and sent a cloud of flour, sidelit and backlit, into the air. Again, the very fast recycling of the SuperFast, allowing up to 20 frames per second to be shot, meant that this was the only practical way of doing it because it would take tremendous luck to be able to catch the rope breaking using the relatively slow recycling of speedlights, and it would have been impossible to freeze this speed of action with any other flash head.

Because of the amount of stretch, and because we couldn’t predict exactly when the rope would break, we just had to keep trying until it happened. Still photos expand time, video compresses time, and it took a lot longer to do in real life than in the video.

We used the SuperFast 300 flash heads for this shoot, the 600 model would have worked just as well as their performance is identical to the 300 model, once the power has been reduced by 1 stop.