No Arduino, no stepper motors, no gears, just a simple motor turning a threaded rod, this barn door tracker rotates your camera at the exact same rate as the rotation of our planet, a requirement for taking long exposure photos.
The concept isnt new, its been around since the 70's, back in the days of 35mm film, my version updates it to motor drive and adds a corrective cam to remove the inherent error in the original version.
Briefly, the common ways of doing this are the single hinge 2 boards with a straight threaded rod, the single hinge 2 boards with a curved threaded rod and the doubled hinged 3 boards version.
All versions can be motorised, but the 2nd version with the curved rod has the motor driving a nut through gearing and the curved rod is held stationary.
An example here of Dennis Harper's curved rod tracker.https://sites.google.com/site/distar97/
Gary Seronik's fine curved rod tracker here http://www.garyseronik.com/?q=node/52
Finally Dave Trott who invented the double-arm tracker. http://davetrott.com/inventions/double-arm-barn-door-drive/
Step 1: Parts and Tools
- A decent hinge with very little play, I went with a solid brass 63mm one seeing as the plank width was 69mm.
- The main part of the tracker, 500mm pine 22m X 69mm.
- The camera mount, approx 300mm of 22mm X 44mm meranti (a hard wood, well harder than pine anyway)
- A brass 1/4" 20 modified machine screw for mounting the camera.
- M8 nut and bolt for mounting the cam mount to the main body.
- M6 rod ~ 90mm with wingnuts and washers for the tilt axis in the camera mount.
- M6 nut and bolt 50mm long for attaching the tracker to the tripod.
- 16 wood screws, 6 for the hinge and 10 for reinforcements in the camera mount.
- A 70mm X 50mm section of plastic cutting board for the corrective cam.
- A 230V AC synchronous 1 rpm motor.
- 2 x steel rods to fit the motor mounts, 4mm in this case.
- M6x1mm threaded rod 135mm long out of which I get a usable length of 90mm, @ 1mm pitch that translates to 90min
- M6 coupling nut to connect the motor shaft to the drive rod with split pins to fit.
- M6 Tee nut for the bottom board's drive rod.
- An existing sturdy mount like a camera tripod or a diy contraption to suit, bear in mind some tripods have a plastic pan tilt head assembly and wobble a fair amount.
Lastly, a camera is also a requirement, preferably a DSLR with remote in order to use the "bulb" setting for long exposures. On my Nikon D70S I use an infrared remote because the camera wont allow bulb setting with the timer, it just overrides with 1/5 sec exposure.
That said, it might be theoretically possible to use a Canon PowerShot (point n shoot range) and load it with the CHDK software to utilise the intervalometer scripts.