NOTE: See the more recent Tracker V2.1 post for a working star-tracking mount.
I’ve recently developed a healthy interest in astrophotography. A very useful tool for photographing the great beyond is an astrotracker. It counters the rotation of the earth (360 degrees per day) and allows for long exposure times without creating star trails. Here’s my POC build- it’s as cheap as borscht and worked great for very light loads. However, it failed to properly support my camera setup- a 5Dc with Tokina 16-28, total mass of over 1.8 kg (without the battery grip). As such, it is to be dismantled and a better version is in the works (waiting on eBay China parts). That said – If you have an SL1 with an EF-S lens (less than 1kg total mass), this may do the trick!
- Screws, 1/4 nuts, 1/4 ready-rod, hot glue
- Linear actuator from DVD-burner
- eBay China L298N dual H-bridge – $4
- eBay China mini breadboard – $1
- Power resistors – $10
- ATTiny85 microcontroller (and programmer)
- Various tidbits here and there
The linear actuator operated on 5v, which meant that our 12v supply needed to be tamed with a couple resistors (biggest cost of the whole project). I used a 11×17 sheet of paper, folded into a tube for the 8xAAA battery holder and a spring to apply pressure to the battery contacts. A cheap battery holder will be a welcome update for the MK2.
As a note for future projects: the linear actuator was excellent for light-duty projects. Do not de-solder the power supply ribbon, instead simply cut it. The ribbon provides support to the feeble leads coming out of the motor (I ruined one motor by treating the leads harshly). The microcontroller was programmed to provide power for a brief duration (500ms) during each step. This greatly reduced heat build-up in the actuator, and likely greatly improved the actuator’s life. Finding a 5v H-bridge would be a nice improvement over the 12v L298N.