I went for a short bike ride with a couple of friends back in grad
school and recorded some video from the ride. I really liked how
some of it looked when I was playing it back - it captured the feeling
of cruising along a trail. I was planning on doing the Commerce
Bank Five Boro Bike Tour with some coworkers and I thought it'd be
cool to try to create some sort of video of the event.
I decided that I'd try to create a time-lapse video of the entire
ride. I was a little apprehensive about mounting my old Canon
Digital Rebel to my bike's handlebars, but I figured it'd be the
easiest to trigger with an external shutter. I didn't feel like
breaking open my point and shoot to get at the shutter release.
To take photos at a fixed interval, I used a 555 timer circuit and a
relay.
I created a
crude camera mount using a few pieces of aluminum and some 1/4-20
thumbscrews. I cut up an old handlebar grip to put between the
handlebars and the clamps.
I eventually used the camera's neck strap to help tether and stabilize
the camera. I should have added another support to keep the
camera from slipping downwards, as it tended to do during the ride
because of all of the bumps and vibrations.
Another photo of the mount.
I set up a 555 timer
in astable mode so that it'd basically output a continuous square wave
with a frequency and duty cycle set by the value of two
resistors. I had the output of the IC connected to trigger a
relay. I based my target time interval between shutter actuations
on an assumption of riding for up to 4 hours while using a 2gb memory
card. I figured I could get between 2000-4000 pictures on the
card depending on ISO speed, at the camera's lowest resolution
(1.5 megapixels)
I decided to conservatively aim for a frame every 10 seconds or
so. with the resistors that I had, the interval ended up being
about 10.6 seconds, according to the scope.
here's the circuit I built up after
testing it on the solderless breadboard. I should have put a
diode on there to protect the timer from the relay coil.
the backside.
I bought a 4xAA battery holder which was plenty for the timer and the
relay. I had to use speaker wire. the actual shutter
release cable was built up from an old nokia headset. there's a
lot of information on building your own cable online. here's
a good example.
I did a pretty ugly job of mounting the power switch.
I used cable ties to secure the electronics box to my water bottle
holder, since I was going to use a backpack hydration system
anyways. I brought three batteries along for the ride and ended
up going through 2 of them.
next time, I'll shorten the interval between pictures. I took
1328 frames in total, and at the end, the camera said that I had 912
images remaining. I'd also redo the camera mount so that it
wouldn't sag as much over time.
-phil (phil#clubantietam.com <--- do these anti-spam tricks
even work??)
