Star Tracker Uses a SAM D21 for Long Exposure Astrophotography

The setup features a Sony Nex-6 camera along with a USB battery pack, making it portable for hiking and camping trips.

Cabe Atwell
23 days agoAstronomy / Robotics / Sensors

Astrophotography is a great hobby that has produced stunning images of celestial bodies over the years. Usually, it requires the use of a wide and fast lens to capture enough light for a detailed picture. This method works for exposure times of up to 30 seconds before stars start to produce concentric circles. Others prefer to grab zoomed images of a particular body in space, which uses a slower lens with more prolonged exposure and is usually mounted on a platform that compensates for the earth’s rotation, eliminating those star trails.

Typically, the rigs capable of tracking stars are on the expensive side, with a lot of them using DSLR cameras mounted on motorized tripods. To that end, Jake Wachlin has created a smaller and more affordable tracker that can easily fit inside of a backpack. His Astrophotography Star Tracker is a single-axis design and features simple bolt hinges, threaded rod actuation, 3D-printed frame, and a Sony Nex-6 camera.

Wachlin built his tracker using a custom PCB outfitted with an ATSAMD21G18A microcontroller, cortex program header, LDO 3.3V regulator, ULN2003A Darlington transistor array, B5B-XH-AM (LF)(SN) connector, and a micro USB port for power. The board drives a 28BYJ-48 stepper motor with 1-DOF, which raises and lowers the 3D-printed camera mount via an M5 threaded rod.

Wachlin states the firmware for his tracker is pretty simple and offers the ability to step the system in two directions manually, and the ability to switch into a system mode that will track a constant rotation rate. He has uploaded a detailed walkthrough of his Astrophotography Star Tracker on his project page, for those interested in recreating his build.

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