DIY Cable Cam

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One of my latest projects has been a Cable Cam. A Cable Cam, as the name suggests, is a camera that runs down a zip line.  Here is mine:

The trolley is made of

  • 2 Clothes line pulleys
  • A length of 2×2
  • A bolt with washers on it to act as a counter balance
  • A camera holder

Click for fullsize.

The camera holder is made out of two pieces of sheet metal that I bent at school.  It allows the camera to pan and tilt.

A 100ft line is stretched between two trees using ratchet straps.  A second line is stretched above it to act as a safety line in case the main line fails.

Click for fullsize.

The whole assembly can fit into a backpack.  This makes it perfect for location shots.

Currently, you have to drag the trolley to the top of the line and then let it go to get footage.  Eventually, I will get an RC car and use that to move the trolley down the line.

6 thoughts on “DIY Cable Cam

  1. Pingback: 3 camera booms for your Wednesday afternoon | Video Game News, reviews, and information.

  2. How about using a pair of winches on one of the trees? tie one end of the rope directly to a tree, and tie a pair of pulleys to the other tree a foot or two higher than the end that’s “dead tied”. Then have a winch connected to the main cable, and another connected to a “haul rope” tied to the carriage. This way, by varying the tension on the main support rope, you can control the height of the camera, and the other rope will control the movement of the camera along the support rope using gravity to move it out and tension on the rope to pull it back. Or use a closed loop to move it back and forth if that makes more sense.

    I would also suggest using servos on the camera mount connected to an Arduino (or other micro-controller) to control the pan and tilt, and maybe the zoom. For the zoom, there’s multiple ways to do this, if the lens has to be manually turned, connect a servo or stepper motor to an elastic band wrapped around the lens barrel to turn it. If it’s already motorized, you could crack the camera open and either wire in a relay control for the T/W buttons, or even control the motor directly from the Arduino. Or even just have solenoids that push the T/W buttons without modifying the camera itself.

    This whole system could be done using JeeNodes (Arduino clones with a built in RF serial link). This way you could have one to control winches for the two ropes, and another mounted on the camera carriage to control pan/tilt/zoom, a solenoid to press the record button, and maybe even LED lighting and/or external microphone direction.

    With this system, you could have the whole rig controlled by a computer, say you’re making a movie and you think you’re going to want to do the same shot multiple times, or for multiple takes, you could program the rig to take the shot you like, save the programming, and run the same shot as many times as you want. If you like the way the shot came out but would like to modify it just slightly, just change one or two values in your programming.

    With automation, you’ll get incredibly smooth movements, you won’t have to worry about the rope jerking with hand-over-hand movements. This whole idea may sound expensive, but believe me, it could be done entirely for less than 100 bucks. If you’re not familiar with micro-controllers, the Arduino is a great entry-level one, I had no experience with them whatsoever, and within a week of buying one, I was already building a CNC machine, they’re incredibly easy to pick up on.

  3. Why don’t you just tie a trucker’s hitch or butterfly knot in lieu of the ratchet strap? I would think you could get more efficient tension with just knots than with the added hardware.

    The safety is a nice touch, but I would recommend using the same parachute cord for your safety that you use for the main line. It looks like you are using polypropylene twine. Good for packages, not so good for overhead rigging.

  4. Try and upgrade to Dyneema wires. Dyneema is “The world’s strongest fiber” and is used in bullet-proof vests, fishing lines, kite flying, sailing, rock climbing …

    How do you move the camera along the wire?

    Be careful with motors on the camera platform as the noise might be heard on the recording.

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