Onstep Telescope Mount Project - Josh Roper Photography

Background

I have always been fascinated by the vastness of space and the beauty of the night sky. As an amateur photographer, I wanted to capture the breathtaking views of the cosmos through astrophotography. However, when I first started experimenting with astrophotography in 2019, I quickly realized that it required specialized equipment and a significant financial investment.

Despite the initial setback, I was determined to find a solution. After some research, I stumbled upon Onstep, an open-source software project that allowed me to repurpose basic electronic components to cheaply build a semi-automated tracking mount.

With Onstep, I was able to build my own tracking mount using a combination of a small computer, a motor controller, and a few other affordable components. The software provided precise tracking, enabling me to capture long exposure images of the night sky.

Not only did Onstep help me achieve my astrophotography goals, but it also opened up new possibilities for me in the realm of electronics and programming.

The Mount

After scouring eBay, I was able to find an old manual-controlled mount that proved to be a fantastic starting point for my Onstep project. After a few iterations, I was able to create some 3d printed brackets that could hold standard-sized NEMA 17 stepper motors.

To ensure that the motors functioned smoothly, I opted for a gear reduction of 4 to 1, which allowed me to achieve the necessary torque even when powered by a 12V battery. Additionally, I chose to use 9-pin D-sub connectors for the connections to the mount controller. I selected these connectors for several reasons, including their ability to screw together securely to handle the movement of the mount. Also, while the stepper motors only have 4 wires, the 9 pin connection allowed me to alternate pins to make soldering easier as I had never soldered before.

Onstep Telescope Mount Project - Josh Roper Photography

The Controller

To control the telescope mount, I utilized a PCB board originally designed to control a 3D printer. The board was already equipped to manage stepper motors and powered by an Arduino-based microcontroller, making it compatible with the Onstep software. Despite some initial trial and error and a brief crash course in the Arduino programming language, I eventually succeeded in installing and configuring the Onstep software getting the mount to function correctly.