Fun with silly putty and a slider.

I wanted to test out how long a Goal Zero Sherpa 100 battery might last for some timelapse projects with a Dynamic Perception Stage One dolly and an eMotimo. I was using eMotimo’s 27:1 AUX stepper motor in “always” powered mode and the eMotimo motors in “shoot (accuracy)” mode. I probably could have put the AUX motor in “shoot (accuracy)” mode as well to conserve power, but I wanted to stress the battery and see how long it would last. I took 3,000 photos over a 36” span down a 25° slope for 2.5hrs, powering the eMotimo, 27:1 stepper motor, and a Nikon D700 (via a 12v to 7.5v step down converter) at indoor temperature (about 72°) and it consumed about 40% of the battery life on the Goal Zero Sherpa 100. That’s not a very scientific measurement; I’m not sure what my load really was in watts, and the digital meter on the front of the battery isn’t all that accurate (it is measured in 20% increments). I think it will handle an overnight timelapse just fine in a more power efficient mode on the AUX motor. I didn’t need 3,000 photos for an 8 second timelapse of course, but this was primarily a battery test.

The second goal was to try a dolly zoom without changing focus or focal length as I don’t yet have motors for that. Some quick calculations told me that 48mm focused at 4ft and f/22 aperture would give me a depth of field from 3 to 6 feet, the range I had my dolly set up for. That necessitated ISO 2500 and a 2 second shutter for a good exposure. I set my interval to 3 seconds on the eMotimo to shoot for 2.5hrs. Looking at the footage later I discovered that the silly putty flattened the most (particularly the sphere) in the first 30-45 minutes and not so much the next 2hrs, so it wasn’t as dramatic as I’d hoped. I should have burned candles or melted ice cubes, but everyone has boring videos of that already.

Since I moved the camera and kept the same focal length, the subject grew larger in every frame. In After Effects I slowly panned out to keep the subject the same relative size to attempt a “dolly zoom” or “vertigo” effect. To really get the effect you need a close subject with a distant background to feel the compression of the depth of field, the table was of course on the same plane as the subject so it’s not very obvious in this test. The silly putty didn’t stay perfectly centered throughout the move, so I tracked it and stabilized it with Mocha in After Effects. There was some slight aperture flicker that I removed via LRTimelapse before importing into After Effects.

So, all that work for a silly 8 second video. Worth it? Nope! Haha! But a good learning experience for things to try in the field later.

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