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Time Lapse Camera
The project
The project is born from an idea of Michele G. The (first but not last) purpose is to take a time-lapse-shot of the traditional bonfire preparation (3-4 days) and burning (1-2 days).
For the purpose we needed something cheap, but powerful. There were many options, this is not the better, simply the one we used.
The camera
If you use a Canon camera take a look at CHDK. This firmware hack maybe would allow you to skip the controller realization. We used a Nikon because was the only affordable and reperible at the time. You should then take it apart and see how the switch works, and take some wires out of it.
The controller
The simple controller goal is to take a photo at regular intervals.
It should trigger the autofocus switch first, and then the shutter switch to take the photo.
Hardware
- Issue #1: The timer. An atmega8 microcontroller (or any other) would be fine. Must draw the smallest current possible. The lapse-interval is set through six dip-switches with weight 2, 4, 8, 16, 32, 64 seconds. A led is for test purposes, it may be disabled removing a jumper. 8 Mhz quartz is optional, actually the internal oscillator would have been enough.
- Issue #2: Power. I've used a pre-built module that converts 9-12V into 5V through an LM2576 based switching step-down converter, and a 7585-3.3 linear regulator that provides 3.3v. An additional diode provides about 0.6v drop, so the camera is powered at about 2.7v. Other cameras may need different power requirements.
Software
Simple C-written code provides timer routine. Features:
- A photo must be taken every N seconds. You select N in the range of 4 to 126 seconds.
- The interval set over the dip-switches is read only at startup (reset) to avoid current dissipation on the pull-up resistors.
- The focus signal is first driven low, then after 2 seconds the shutter signal is driven low, another second and both are released to hi-z state.
- An optional led shows when the photo is being taken (lits up when focusing, turns down a second after the shot).